{ "name": "Loupewise Gem Property Dataset", "description": "Physical and optical properties for 132 gem entries, with per-entry source keys.", "version": "4fbacd51ce04", "dateModified": "2026-10-09", "license": "https://creativecommons.org/licenses/by/4.0/", "attribution": "Loupewise. Loupewise Gem Property Dataset (version 4fbacd51ce04). 2026-10-09. Licensed CC BY 4.0. https://gemid-labs.com/data/", "url": "https://gemid-labs.com/data/", "recordCount": 132, "fields": [ { "name": "id", "description": "Stable identifier used across the dataset and site." }, { "name": "name", "description": "Common trade or varietal name." }, { "name": "species", "description": "Mineral species the entry belongs to." }, { "name": "variety", "description": "Variety name within the species." }, { "name": "crystal_system", "description": "Crystal system." }, { "name": "optic_character", "description": "SR (singly refractive), DR_U/DR_B (uniaxial/biaxial, + or −), or AGG (aggregate)." }, { "name": "adr", "description": "Whether the material commonly shows anomalous double refraction." }, { "name": "ri_min", "description": "Lowest refractive index recorded for the entry." }, { "name": "ri_max", "description": "Highest refractive index recorded for the entry." }, { "name": "birefringence", "description": "Maximum minus minimum RI. Empty for singly refractive and aggregate material, which has no birefringence rather than a birefringence of zero." }, { "name": "dispersion", "description": "Dispersion (B–G interval). Empty where no value is recorded — mostly opaque, aggregate or organic material whose fire is not observable. Until 2026-10-09 these 17 entries carried 0, a placeholder rather than a measurement." }, { "name": "sg_min", "description": "Lowest specific gravity recorded." }, { "name": "sg_max", "description": "Highest specific gravity recorded." }, { "name": "sg_typical", "description": "Representative specific gravity within that range." }, { "name": "hardness_min", "description": "Lowest Mohs hardness recorded." }, { "name": "hardness_max", "description": "Highest Mohs hardness recorded." }, { "name": "cleavage", "description": "Cleavage quality and direction." }, { "name": "fracture_type", "description": "Characteristic fracture." }, { "name": "crystal_habits", "description": "Habits the material commonly forms in." }, { "name": "luster", "description": "Luster terms that apply." }, { "name": "transparency", "description": "Transparency range." }, { "name": "color_categories", "description": "Broad colour bands the material occurs in." }, { "name": "pleochroism", "description": "Pleochroism strength: none, weak, moderate, strong_dichroic or strong_trichroic." }, { "name": "pleochroic_colors", "description": "Twin or triplet colours where recorded." }, { "name": "facet_doubling", "description": "Whether facet doubling is visible through the crown." }, { "name": "facet_doubling_strength", "description": "Strength of that doubling." }, { "name": "magnetism", "description": "Response to a neodymium magnet." }, { "name": "fluorescence_lw", "description": "Long-wave (365 nm) UV response." }, { "name": "fluorescence_sw", "description": "Short-wave (254 nm) UV response." }, { "name": "chelsea_filter", "description": "Appearance through a Chelsea filter." }, { "name": "hanneman_filter", "description": "Appearance through a Hanneman filter." }, { "name": "spectroscope_absorption", "description": "Absorption features described for the visible spectrum." }, { "name": "thermal_test", "description": "How the material reads on a diamond thermal probe." }, { "name": "sources", "description": "Reference keys supporting the physical and optical properties in this row." } ], "data": [ { "id": "agate", "name": "Agate", "species": "Quartz", "variety": "Agate", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "cryptocrystalline", "banded", "massive", "nodular" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "multi", "colorless", "red_pink", "yellow_orange", "brown", "blue_violet", "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_white", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "alexandrite", "name": "Alexandrite", "species": "Chrysoberyl", "variety": "Alexandrite", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.746, "ri_max": 1.755, "birefringence": 0.009, "dispersion": 0.015, "sg_min": 3.7, "sg_max": 3.78, "sg_typical": 3.73, "hardness_min": 8.5, "hardness_max": 8.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "color_change", "green", "red_pink" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "green", "orange", "purple-red" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "moderate_red", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "680.3 nm — Cr³⁺ doublet (strong, diagnostic; the narrower line of the alexandrite doublet)", "678.5 nm — Cr³⁺ doublet companion (strong; broader companion line)", "665 nm — Cr absorption band (moderate)", "645 nm — Cr absorption band shoulder (moderate)", "580–620 nm — Broad absorption in orange region causing red/green color change" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "SCHMETZER_2010" ] }, { "id": "almandine_garnet", "name": "Almandine Garnet", "species": "Garnet", "variety": "Almandine", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.77, "ri_max": 1.83, "birefringence": null, "dispersion": 0.024, "sg_min": 3.93, "sg_max": 4.3, "sg_typical": 4.05, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "rhombohedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink", "purple", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "almandite_trio", "504 nm — Fe²⁺ band (strong, primary; most diagnostic band of the almandine trio)", "520 nm — Fe²⁺ band (strong; central band of the diagnostic yellow-green trio)", "573 nm — Fe²⁺ band (strong; third band completing the diagnostic trio)", "527 nm — Fe²⁺ secondary band (moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "amazonite", "name": "Amazonite", "species": "Feldspar", "variety": "Microcline", "crystal_system": "triclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.514, "ri_max": 1.53, "birefringence": 0.008, "dispersion": 0.012, "sg_min": 2.54, "sg_max": 2.58, "sg_typical": 2.56, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "short columnar", "massive", "granular" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "blue_violet" ], "pleochroism": "weak", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad absorption band ~625–643 nm (blue color variety, Pb⁺ color center)", "Broad absorption band ~720–740 nm (green color variety, O⁻–Pb⁺ color center)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "amber", "name": "Amber", "species": "Organic", "variety": null, "crystal_system": "amorphous", "optic_character": "SR", "adr": true, "ri_min": 1.539, "ri_max": 1.545, "birefringence": null, "dispersion": null, "sg_min": 1.05, "sg_max": 1.09, "sg_typical": 1.08, "hardness_min": 2, "hardness_max": 2.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal" ], "luster": [ "resinous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "yellow_orange", "brown", "red_pink", "green", "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_blue", "fluorescence_sw": "moderate_blue_white", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "amethyst", "name": "Amethyst", "species": "Quartz", "variety": "Amethyst", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.65, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "purple", "blue_violet" ], "pleochroism": "weak", "pleochroic_colors": [ "purplish-red", "bluish-purple" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "550 nm — Fe³⁺ broad absorption band (moderate; responsible for purple color in combination with color centers)", "530 nm — Absorption shoulder (weak to moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "ametrine", "name": "Ametrine", "species": "Quartz", "variety": "Ametrine", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.67, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "rhombohedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "purple", "yellow_orange" ], "pleochroism": "weak", "pleochroic_colors": [ "pale purple", "pale yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Broad absorption band centered ~540 nm (amethyst zones, Fe³⁺/Fe⁴⁺ charge transfer)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "andalusite", "name": "Andalusite", "species": "Andalusite (Al₂SiO₅)", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.629, "ri_max": 1.649, "birefringence": 0.01, "dispersion": 0.016, "sg_min": 3.13, "sg_max": 3.21, "sg_typical": 3.17, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green", "brown", "yellow_orange" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "green", "red-brown", "yellow-orange" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "553 nm — Mn³⁺ absorption band (moderate; responsible for green pleochroic color)", "550 nm — Broad Mn absorption region (strongest in green direction)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "apatite", "name": "Apatite", "species": "Apatite", "variety": null, "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.628, "ri_max": 1.649, "birefringence": 0.006, "dispersion": 0.013, "sg_min": 3.17, "sg_max": 3.23, "sg_typical": 3.2, "hardness_min": 5, "hardness_max": 5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "green", "yellow_orange", "colorless" ], "pleochroism": "moderate", "pleochroic_colors": [ "colorless", "blue" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "512 nm — Rare earth (Dy³⁺) band (moderate; present in some yellow-green apatite)", "491 nm — Rare earth band (weak; Pr³⁺ in some specimens)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "aquamarine", "name": "Aquamarine", "species": "Beryl", "variety": "Aquamarine", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.577, "ri_max": 1.583, "birefringence": 0.006, "dispersion": 0.014, "sg_min": 2.68, "sg_max": 2.78, "sg_typical": 2.72, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "weak", "pleochroic_colors": [ "colorless", "light blue" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "537 nm — Fe²⁺ band (strong; primary diagnostic iron band for aquamarine)", "456 nm — Fe²⁺ band (moderate; iron absorption in violet-blue region)", "427 nm — Fe²⁺ band (weak to moderate; short wavelength iron band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "aventurine", "name": "Aventurine", "species": "Quartz", "variety": "Aventurine", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": null, "dispersion": 0.013, "sg_min": 2.64, "sg_max": 2.69, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "granular" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent" ], "color_categories": [ "green", "blue_violet", "red_pink", "yellow_orange", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Chromium (Cr³⁺) absorption from fuchsite inclusions: bands ~450 nm and ~600–680 nm" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "benitoite", "name": "Benitoite", "species": "Benitoite", "variety": null, "crystal_system": "hexagonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.757, "ri_max": 1.804, "birefringence": 0.047, "dispersion": 0.046, "sg_min": 3.64, "sg_max": 3.68, "sg_typical": 3.66, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet" ], "pleochroism": "moderate", "pleochroic_colors": [ "blue", "colorless" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "strong_blue_white", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "435 nm — Absorption band (moderate; related to Ti content in benitoite)", "412 nm — Absorption band (weak)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "black_opal", "name": "Black Opal", "species": "Opal", "variety": "Black Opal", "crystal_system": "amorphous", "optic_character": "SR", "adr": false, "ri_min": 1.44, "ri_max": 1.46, "birefringence": null, "dispersion": null, "sg_min": 2.09, "sg_max": 2.16, "sg_typical": 2.1, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "amorphous", "massive", "nodular" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "opaque", "translucent" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "black_spinel", "name": "Black Spinel", "species": "Spinel", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.712, "ri_max": 1.73, "birefringence": null, "dispersion": 0.02, "sg_min": 3.58, "sg_max": 3.61, "sg_typical": 3.6, "hardness_min": 8, "hardness_max": 8, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "massive" ], "luster": [ "vitreous" ], "transparency": [ "opaque" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic visible bands — black spinel shows general absorption; Fe-Ti charge transfer causes near-complete absorption throughout visible spectrum in opaque specimens" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "bloodstone", "name": "Bloodstone", "species": "Quartz", "variety": "Bloodstone (Heliotrope)", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "cryptocrystalline" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "opaque" ], "color_categories": [ "green", "multi" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad Fe absorption; diffuse bands in the red ~630–670 nm region from iron oxide/hematite inclusions" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "blue_diamond", "name": "Blue Diamond", "species": "Diamond", "variety": "Fancy Blue", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.417, "ri_max": 2.417, "birefringence": null, "dispersion": 0.044, "sg_min": 3.5, "sg_max": 3.53, "sg_typical": 3.52, "hardness_min": 10, "hardness_max": 10, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "cubic" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "strong_orange", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Broad boron-related absorption tail extending from near-infrared into red visible region (responsible for blue colour in Type IIb; diffuse — no sharp discrete line visible in hand spectroscope)", "No sharp diagnostic lines in visible range — FTIR (2800 cm⁻¹ region) is the definitive boron test; hand spectroscope is not diagnostic for blue diamonds" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "brown_diamond", "name": "Brown Diamond", "species": "Diamond", "variety": "Fancy Brown Diamond (Champagne / Cognac)", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.417, "ri_max": 2.417, "birefringence": null, "dispersion": 0.044, "sg_min": 3.51, "sg_max": 3.53, "sg_typical": 3.52, "hardness_min": 10, "hardness_max": 10, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "dodecahedral", "cubic" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "n3_415nm", "h3_503nm", "gr1_741nm" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "calcite", "name": "Calcite", "species": "Calcite", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.486, "ri_max": 1.658, "birefringence": 0.172, "dispersion": 0.017, "sg_min": 2.67, "sg_max": 2.73, "sg_typical": 2.71, "hardness_min": 3, "hardness_max": 3, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "rhombohedral", "scalenohedral", "massive", "stalactitic" ], "luster": [ "vitreous", "pearly", "resinous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "colorless", "yellow_orange", "green", "red_pink", "blue_violet", "brown", "multi" ], "pleochroism": "weak", "pleochroic_colors": [], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [], "thermal_test": "simulant", "sources": [ "HANDBOOK_MINERALOGY", "GEMDAT", "GIA_GUBELIN_DB", "READ_2005" ] }, { "id": "carnelian", "name": "Carnelian", "species": "Quartz", "variety": "Carnelian", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "cryptocrystalline", "nodular" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent" ], "color_categories": [ "red_pink", "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_white", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad diffuse iron absorption bands centered near 580 nm, 610 nm, 630 nm, 640 nm, and 665 nm" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "cassiterite", "name": "Cassiterite", "species": "Cassiterite", "variety": null, "crystal_system": "tetragonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.997, "ri_max": 2.093, "birefringence": 0.096, "dispersion": 0.071, "sg_min": 6.8, "sg_max": 7.1, "sg_typical": 6.95, "hardness_min": 6, "hardness_max": 7, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "pyramidal", "twinned", "massive" ], "luster": [ "adamantine", "metallic" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "brown", "black", "yellow_orange" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "yellow-brown", "red-brown" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Strong absorption in the near-UV to violet region, ~350–400 nm (shifts by color variety)", "Brownish-pink varieties show broad band centered ~490 nm" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "cat_eye_chrysoberyl", "name": "Cat's Eye Chrysoberyl", "species": "Chrysoberyl", "variety": "Cymophane", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.746, "ri_max": 1.755, "birefringence": 0.009, "dispersion": 0.015, "sg_min": 3.7, "sg_max": 3.78, "sg_typical": 3.73, "hardness_min": 8.5, "hardness_max": 8.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "prismatic" ], "luster": [ "vitreous", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "yellow_orange", "green", "brown" ], "pleochroism": "weak", "pleochroic_colors": [ "colorless", "yellow", "green" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "444 nm — Fe³⁺ absorption band (strong; visible in hand spectroscope — diagnostic for chrysoberyl vs quartz cat's-eye)", "484–505 nm — Fe³⁺ weaker band region (sometimes visible as a diffuse absorption edge in blue-green)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "SCHMETZER_2010" ] }, { "id": "chalcedony", "name": "Chalcedony", "species": "Quartz", "variety": "Chalcedony", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal", "cryptocrystalline", "stalactitic" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "colorless", "blue_violet", "brown", "multi" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_white", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "charoite", "name": "Charoite", "species": "Charoite", "variety": null, "crystal_system": "monoclinic", "optic_character": "AGG", "adr": false, "ri_min": 1.55, "ri_max": 1.559, "birefringence": null, "dispersion": 0.005, "sg_min": 2.54, "sg_max": 2.68, "sg_typical": 2.6, "hardness_min": 5, "hardness_max": 6, "cleavage": "perfect", "fracture_type": "uneven", "crystal_habits": [ "massive", "fibrous" ], "luster": [ "vitreous", "silky" ], "transparency": [ "opaque" ], "color_categories": [ "purple" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_orange", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "chrome_diopside", "name": "Chrome Diopside", "species": "Diopside (pyroxene)", "variety": "Chrome Diopside", "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.664, "ri_max": 1.73, "birefringence": 0.03, "dispersion": 0.02, "sg_min": 3.22, "sg_max": 3.38, "sg_typical": 3.3, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "green" ], "pleochroism": "moderate", "pleochroic_colors": [ "bluish-green", "yellowish-green" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "690 nm — Cr³⁺ doublet line (strong; primary diagnostic chromium band for chrome diopside)", "686 nm — Cr³⁺ doublet companion (strong; paired with 690nm)", "506 nm — Fe²⁺ band (moderate; iron absorption also present in diopside)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "chrome_tourmaline", "name": "Chrome Tourmaline", "species": "Tourmaline", "variety": "Chromian Dravite or Chromian Elbaite", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.624, "ri_max": 1.66, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3, "sg_max": 3.2, "sg_typical": 3.1, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated_prism_faces", "trigonal_cross_section" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "dark green", "brownish-green" ], "facet_doubling": true, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "637 nm — Cr³⁺ line (strong; primary diagnostic chromium line in chrome tourmaline)", "620 nm — Cr³⁺ band (moderate; secondary chromium band)", "478 nm — Cr³⁺ broad absorption (strong; blue-violet chromium absorption region)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "clinohumite", "name": "Clinohumite", "species": "Clinohumite (Mg,Fe)₉(SiO₄)₄(F,OH)₂", "variety": null, "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.625, "ri_max": 1.675, "birefringence": 0.028, "dispersion": 0.022, "sg_min": 3.13, "sg_max": 3.35, "sg_typical": 3.21, "hardness_min": 6, "hardness_max": 6, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular", "massive" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange", "brown" ], "pleochroism": "weak", "pleochroic_colors": [ "yellow", "pale yellow", "orange-yellow" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "strong_orange", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~450 nm — general absorption cut-off in the violet (strong; Fe²⁺ in octahedral sites)", "~540 nm — broad absorption band in the green-yellow region (moderate; Fe²⁺, causes yellow-orange body color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "ODONOGHUE_2006", "SCHUMANN_2017" ] }, { "id": "chrysoberyl", "name": "Chrysoberyl", "species": "Chrysoberyl", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.746, "ri_max": 1.755, "birefringence": 0.009, "dispersion": 0.015, "sg_min": 3.7, "sg_max": 3.78, "sg_typical": 3.73, "hardness_min": 8.5, "hardness_max": 8.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "green", "brown" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "yellow", "green" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "444 nm — Fe³⁺ band (moderate; most visible in yellow-green chrysoberyl; iron absorption in blue-violet region)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "SCHMETZER_2010" ] }, { "id": "chrysocolla", "name": "Chrysocolla", "species": "Chrysocolla", "variety": null, "crystal_system": "orthorhombic", "optic_character": "AGG", "adr": false, "ri_min": 1.575, "ri_max": 1.635, "birefringence": null, "dispersion": null, "sg_min": 1.93, "sg_max": 2.4, "sg_typical": 2.2, "hardness_min": 2, "hardness_max": 4, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal", "earthy", "cryptocrystalline" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Broad Cu²⁺ absorption centered near 700–800 nm in orange-red region (responsible for blue-green colour transmission; visible as general red suppression rather than a discrete line)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HANDBOOK_MINERALOGY" ] }, { "id": "chrysoprase", "name": "Chrysoprase", "species": "Quartz", "variety": "Chrysoprase", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "cryptocrystalline", "nodular" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad Ni²⁺ absorption centered near 630–660 nm in orange-red region (responsible for green colour; no sharp lines — visible as diffuse red-end suppression in hand spectroscope)", "Secondary Ni²⁺ absorption near 380–400 nm in UV-violet region (contributes to overall colour balance)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "cinnabar", "name": "Cinnabar", "species": "Cinnabar", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 2.905, "ri_max": 3.256, "birefringence": 0.351, "dispersion": 0.4, "sg_min": 8, "sg_max": 8.2, "sg_typical": 8.1, "hardness_min": 2, "hardness_max": 2.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "rhombohedral", "tabular", "massive", "granular" ], "luster": [ "adamantine", "metallic" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink", "brown" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "red", "brownish red" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~600 nm — strong absorption edge; blue-violet and green regions essentially cut off (band-gap absorption in HgS causes intense red/vermilion color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "citrine", "name": "Citrine", "species": "Quartz", "variety": "Citrine", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.65, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "brown" ], "pleochroism": "weak", "pleochroic_colors": [ "light yellow", "deep yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "432 nm — Fe³⁺ band (weak; present in natural citrine; distinguishes from glass simulants)", "420 nm — Fe³⁺ band shoulder (weak; often faint in heat-treated amethyst/citrine)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "color_change_garnet", "name": "Color-Change Garnet", "species": "Garnet", "variety": "Pyrope-Spessartite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.74, "ri_max": 1.765, "birefringence": null, "dispersion": 0.026, "sg_min": 3.65, "sg_max": 3.8, "sg_typical": 3.72, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "color_change", "blue_violet", "green", "red_pink", "purple" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "moderate", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "almandite_trio" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "color_change_sapphire", "name": "Color-Change Sapphire", "species": "Corundum", "variety": "Color-Change Sapphire", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.99, "sg_max": 4.01, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "purple", "color_change" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "blue-green", "purple-violet" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": null, "spectroscope_absorption": [ "450 nm — Fe²⁺/Fe³⁺ iron band (moderate; same as blue sapphire component)", "693 nm — Cr³⁺ line (weak to moderate; responsible for red/purple component in incandescent light)", "460 nm — Fe²⁺ iron band (moderate; contributes to blue component)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "coral", "name": "Coral", "species": "Organic", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.486, "ri_max": 1.658, "birefringence": null, "dispersion": null, "sg_min": 2.6, "sg_max": 2.7, "sg_typical": 2.68, "hardness_min": 3, "hardness_max": 4, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "organic", "columnar", "branching" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink", "colorless", "black", "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "cubic_zirconia", "name": "Cubic Zirconia", "species": "Man-made", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.15, "ri_max": 2.18, "birefringence": null, "dispersion": 0.066, "sg_min": 5.6, "sg_max": 6, "sg_typical": 5.8, "hardness_min": 8, "hardness_max": 8.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "boule" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "red_pink", "blue_violet", "green", "yellow_orange", "brown", "purple", "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Colorless CZ: no diagnostic absorption bands in the visible spectrum", "Erbium-doped CZ: 518 nm and 524 nm — sharp doublet absorption lines in the green (strong; rare-earth Er³⁺); additional lines in violet, blue, and red", "Holmium-doped CZ: ~540 nm — narrow absorption in the green (strong; rare-earth Ho³⁺)", "Neodymium+erbium-doped CZ (tanzanite simulant): ~485–490 nm, ~520–525 nm, ~650 nm (broad group) — rare-earth absorption complex" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "cuprite", "name": "Cuprite", "species": "Cuprite", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 2.849, "ri_max": 2.849, "birefringence": null, "dispersion": 0.155, "sg_min": 5.85, "sg_max": 6.15, "sg_typical": 6.14, "hardness_min": 3.5, "hardness_max": 4, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "cubic", "octahedral", "dodecahedral", "massive", "capillary" ], "luster": [ "adamantine", "metallic" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~450–530 nm — broad, strong absorption across blue to green-yellow (band-gap and charge-transfer absorption in Cu₂O; causes deep red color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "danburite", "name": "Danburite", "species": "Danburite (CaB₂Si₂O₈)", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.627, "ri_max": 1.636, "birefringence": 0.006, "dispersion": 0.017, "sg_min": 2.97, "sg_max": 3.02, "sg_typical": 3, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "wedge-shaped" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "yellow_orange", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_blue", "fluorescence_sw": "strong_blue", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands — danburite shows a clean featureless spectrum; colorless to pale yellow specimens are essentially transparent across the visible range" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "demantoid_garnet", "name": "Demantoid Garnet", "species": "Garnet", "variety": "Demantoid", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.88, "ri_max": 1.895, "birefringence": null, "dispersion": 0.057, "sg_min": 3.82, "sg_max": 3.88, "sg_typical": 3.84, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "green", "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "701 nm — Fe³⁺ band (strong; primary iron band for andradite/demantoid garnet)", "640 nm — Cr³⁺ band (moderate; chromium absorption in Cr-rich specimens)", "620 nm — Fe³⁺ band (moderate)", "443 nm — Fe²⁺ band (strong; characteristic blue-violet absorption band for demantoid/andradite garnet)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "diamond", "name": "Diamond", "species": "Diamond", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.417, "ri_max": 2.417, "birefringence": null, "dispersion": 0.044, "sg_min": 3.5, "sg_max": 3.53, "sg_typical": 3.52, "hardness_min": 10, "hardness_max": 10, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "cubic", "dodecahedral" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "yellow_orange", "brown", "red_pink", "blue_violet", "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "line_415" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "diaspore", "name": "Diaspore", "species": "Diaspore", "variety": "Color-Change Diaspore", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.702, "ri_max": 1.752, "birefringence": 0.048, "dispersion": 0.02, "sg_min": 3.3, "sg_max": 3.39, "sg_typical": 3.35, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "platy", "lamellar", "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "color_change", "green", "yellow_orange", "red_pink" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "pale yellow-green", "pink-champagne" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "453 nm — Mn³⁺ absorption band (strong; responsible for the color-change effect in diaspore)", "584 nm — Mn³⁺ band (moderate)", "550 nm — Mn/Fe broad absorption (moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "emerald", "name": "Emerald", "species": "Beryl", "variety": "Emerald", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.565, "ri_max": 1.602, "birefringence": 0.006, "dispersion": 0.014, "sg_min": 2.67, "sg_max": 2.78, "sg_typical": 2.72, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "green" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "bluish-green", "yellowish-green" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "red", "spectroscope_absorption": [ "683 nm — Cr³⁺ doublet line (strong, diagnostic; primary line of emerald's chromium doublet)", "680 nm — Cr³⁺ doublet companion (strong; paired with 683nm line, diagnostic for chromium coloration)", "477 nm — Cr³⁺ broad absorption band (strong; causes absorption of violet-blue light)", "427 nm — Cr³⁺ band (moderate; short wavelength chromium band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "enstatite", "name": "Enstatite", "species": "Enstatite (pyroxene — MgSiO₃)", "variety": "Chrome Enstatite", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.663, "ri_max": 1.673, "birefringence": 0.01, "dispersion": 0.017, "sg_min": 3.2, "sg_max": 3.3, "sg_typical": 3.27, "hardness_min": 5, "hardness_max": 5.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "green" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "green", "yellow-green", "brown-green" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "506 nm — Fe²⁺ sharp diagnostic line (strong; characteristic of enstatite; most reliably seen in brownish/yellowish-green material)", "427 nm — Fe²⁺ weaker band (visible in iron-bearing specimens)", "546 nm — Fe²⁺ weaker band (visible in iron-bearing specimens)", "645 nm — Cr³⁺ band (present only in chromium-bearing green enstatite)", "655 nm — Cr³⁺ band (present only in chromium-bearing green enstatite)", "684 nm — Cr³⁺ band (present only in chromium-bearing green enstatite; Cr³⁺ photoluminescence doublet at ~681–686 nm may also be seen)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "fire_opal", "name": "Fire Opal", "species": "Opal", "variety": "Fire Opal", "crystal_system": "amorphous", "optic_character": "SR", "adr": false, "ri_min": 1.37, "ri_max": 1.47, "birefringence": null, "dispersion": null, "sg_min": 1.98, "sg_max": 2.2, "sg_typical": 2, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "amorphous", "massive", "nodular", "stalactitic" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "fluorite", "name": "Fluorite", "species": "Fluorite", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 1.432, "ri_max": 1.436, "birefringence": null, "dispersion": 0.007, "sg_min": 3.17, "sg_max": 3.19, "sg_typical": 3.18, "hardness_min": 4, "hardness_max": 4, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "cubic", "octahedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "purple", "blue_violet", "green", "yellow_orange", "colorless", "red_pink", "color_change" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_blue", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "No diagnostic absorption bands — spectrum generally clean (fluorite is typically featureless in the visible range)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "goshenite", "name": "Goshenite", "species": "Beryl", "variety": "Goshenite (Colorless Beryl)", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.577, "ri_max": 1.583, "birefringence": 0.006, "dispersion": 0.014, "sg_min": 2.68, "sg_max": 2.8, "sg_typical": 2.72, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "grandidierite", "name": "Grandidierite", "species": "Grandidierite ((Mg,Fe)Al₃(BO₃)(SiO₄)O₂)", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.59, "ri_max": 1.623, "birefringence": 0.033, "dispersion": 0.015, "sg_min": 2.85, "sg_max": 2.98, "sg_typical": 2.95, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "dark blue-green", "colorless", "dark green" ], "facet_doubling": true, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "480–490 nm — Fe²⁺ absorption doublet (weak to moderate; visible in hand spectroscope in face-up orientation — useful diagnostic for this rare gem)", "Broad Fe²⁺/Fe³⁺ absorption in orange-red region contributing to strong trichroism (dark blue-green / colorless / dark green)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "green_tourmaline", "name": "Green Tourmaline", "species": "Tourmaline", "variety": "Verdelite (Elbaite)", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.616, "ri_max": 1.65, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3, "sg_max": 3.1, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated_prism_faces", "trigonal_cross_section" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "dark green", "yellowish-green" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "496 nm — Fe absorption band", "611 nm — Fe absorption band" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "grossular_garnet", "name": "Grossular Garnet", "species": "Garnet (grossular — calcium aluminum silicate)", "variety": "Leuco-grossular / Merelani Mint Grossular", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.734, "ri_max": 1.759, "birefringence": null, "dispersion": 0.028, "sg_min": 3.57, "sg_max": 3.73, "sg_typical": 3.61, "hardness_min": 6.5, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous", "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_orange", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "407 nm — Fe³⁺ absorption band (weak; present in Fe-bearing grossular varieties)", "430 nm — Fe³⁺ broad absorption (weak to moderate; varies with iron content)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "hackmanite", "name": "Hackmanite", "species": "Sodalite", "variety": "Hackmanite (Tenebrescent Sodalite)", "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 1.483, "ri_max": 1.487, "birefringence": null, "dispersion": 0.018, "sg_min": 2.27, "sg_max": 2.4, "sg_typical": 2.27, "hardness_min": 5.5, "hardness_max": 6, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "massive" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "colorless", "purple", "red_pink", "color_change" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_orange_pink", "fluorescence_sw": "moderate_orange_pink", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~540 nm — F-centre / colour-centre absorption (moderate; responsible for pink-to-purple photochromic colour when UV-activated; present only after UV exposure — fades in daylight)", "No diagnostic bands visible in hand spectroscope on untreated/unactivated material" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "hauyne", "name": "Hauyne", "species": "Hauyne (Na,Ca)₄₋₈Al₆Si₆O₂₄(SO₄,S)₁₋₂", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 1.494, "ri_max": 1.509, "birefringence": null, "dispersion": 0.019, "sg_min": 2.44, "sg_max": 2.5, "sg_typical": 2.47, "hardness_min": 5.5, "hardness_max": 6, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "octahedral", "massive", "granular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_orange_pink", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad S₃·⁻ radical absorption centered near 595–620 nm in orange region (responsible for intense blue colour; diffuse — visible as general orange-red suppression in hand spectroscope rather than a discrete line)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "ODONOGHUE_2006", "SCHUMANN_2017" ] }, { "id": "hawks_eye", "name": "Hawk's Eye", "species": "Quartz", "variety": "Hawk's Eye", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": null, "dispersion": 0.013, "sg_min": 2.64, "sg_max": 2.71, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "fibrous", "massive" ], "luster": [ "silky", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; residual Fe absorption from crocidolite/riebeckite fibers not resolvable in hand spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "heliodor", "name": "Heliodor", "species": "Beryl", "variety": "Heliodor", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.568, "ri_max": 1.58, "birefringence": 0.006, "dispersion": 0.014, "sg_min": 2.68, "sg_max": 2.74, "sg_typical": 2.72, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "columnar", "striated" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange", "green" ], "pleochroism": "weak", "pleochroic_colors": [ "pale yellow", "greenish-yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "537 nm — Fe²⁺ band (strong; primary diagnostic iron band, same as aquamarine but typically stronger in heliodor)", "456 nm — Fe²⁺ band (moderate)", "427 nm — Fe²⁺ band (weak)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "hematite", "name": "Hematite", "species": "Hematite", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 2.94, "ri_max": 3.22, "birefringence": 0.28, "dispersion": null, "sg_min": 4.95, "sg_max": 5.3, "sg_typical": 5.28, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "platy", "rhombohedral", "massive", "botryoidal", "reniform" ], "luster": [ "metallic" ], "transparency": [ "opaque" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands visible in the visible spectrum with a hand spectroscope (opaque metallic material; broad Fe₂O₃ absorption throughout visible range)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "grossular_hessonite_garnet", "name": "Hessonite Garnet", "species": "Garnet", "variety": "Grossular / Hessonite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.73, "ri_max": 1.76, "birefringence": null, "dispersion": 0.028, "sg_min": 3.59, "sg_max": 3.65, "sg_typical": 3.61, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "trapezohedron", "massive" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "brown", "green", "red_pink", "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "432 nm — Mn²⁺ absorption band (moderate; iron-manganese grossular variety)", "410 nm — Fe³⁺ band (weak to moderate; hessonite contains Fe-Mn in solid solution)", "407 nm — Fe³⁺ band (weak)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "hiddenite", "name": "Hiddenite", "species": "Spodumene", "variety": "Hiddenite", "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.66, "ri_max": 1.676, "birefringence": 0.016, "dispersion": 0.017, "sg_min": 3.15, "sg_max": 3.21, "sg_typical": 3.18, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated", "spear-shaped" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "yellow-green", "emerald green" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "variable", "spectroscope_absorption": [ "686 nm — Cr³⁺ line (strong; primary chromium line in hiddenite/spodumene)", "669 nm — Cr³⁺ companion line (strong)", "646 nm — Cr³⁺ band (moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "howlite", "name": "Howlite", "species": "Howlite", "variety": null, "crystal_system": "monoclinic", "optic_character": "AGG", "adr": false, "ri_min": 1.583, "ri_max": 1.608, "birefringence": null, "dispersion": null, "sg_min": 2.45, "sg_max": 2.58, "sg_typical": 2.53, "hardness_min": 3.5, "hardness_max": 3.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "nodular" ], "luster": [ "waxy" ], "transparency": [ "opaque" ], "color_categories": [ "colorless", "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_blue", "fluorescence_sw": "weak_blue_white", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "indicolite", "name": "Indicolite", "species": "Tourmaline", "variety": "Indicolite", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.624, "ri_max": 1.644, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3.02, "sg_max": 3.1, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated", "columnar" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "blue_violet" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "dark blue", "light blue" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "498 nm — Fe²⁺ band (strong; primary iron band in blue tourmaline)", "455 nm — Fe²⁺ band (moderate)", "640 nm — Fe²⁺ band (moderate; in deeply colored indicolite)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "iolite", "name": "Iolite", "species": "Cordierite", "variety": "Iolite", "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.54, "ri_max": 1.56, "birefringence": 0.012, "dispersion": 0.017, "sg_min": 2.57, "sg_max": 2.66, "sg_typical": 2.59, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "blue_violet", "purple" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "violet-blue", "light blue", "yellow-gray" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "645 nm — Fe²⁺ band (strong; primary absorption in blue/violet iolite)", "593 nm — Fe²⁺ band (strong; diagnostic for iolite)", "585 nm — Fe²⁺ band (strong; part of diagnostic iron band group)", "535 nm — Fe²⁺ band (moderate; mid-spectrum iron absorption)", "492 nm — Fe²⁺ band (moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ], "source_discrepancies": [ { "property": "refractive_index", "note": "Cordierite (iolite) RI varies with Mg/Fe composition, so published reference ranges differ by exam body. The app uses the Gem-A syllabus range for identification; GIA candidates should expect GIA's narrower nominal range.", "engine_value": "1.54–1.56", "by_credential": { "gia": { "value": "1.542–1.551", "source": "GIA lab manual" }, "fga": { "value": "1.54–1.56", "source": "Gem-A syllabus constants" }, "feeg": { "value": "1.54–1.56", "source": "Gem-A / Webster" } } } ] }, { "id": "ivory", "name": "Ivory", "species": "Organic", "variety": "Ivory (Elephant / Mammoth)", "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.535, "ri_max": 1.54, "birefringence": null, "dispersion": null, "sg_min": 1.7, "sg_max": 1.98, "sg_typical": 1.85, "hardness_min": 2.5, "hardness_max": 3, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "organic", "tusk-shaped" ], "luster": [ "waxy" ], "transparency": [ "opaque" ], "color_categories": [ "colorless", "yellow_orange", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_blue_white", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "jadeite", "name": "Jadeite", "species": "Jadeite", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.654, "ri_max": 1.688, "birefringence": null, "dispersion": null, "sg_min": 3.24, "sg_max": 3.43, "sg_typical": 3.34, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "splintery", "crystal_habits": [ "massive" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "purple", "colorless", "black", "red_pink", "yellow_orange", "multi" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "437 nm — Fe³⁺ band (strong; diagnostic for jadeite; most visible in lavender/white jadeite)", "630–690 nm — Cr³⁺ bands (strong in imperial green jadeite; chromium doublet-like absorption producing vivid green; absent in Fe-colored greens)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "jet", "name": "Jet", "species": "Organic Mineraloid (compact lignite)", "variety": null, "crystal_system": "amorphous", "optic_character": "SR", "adr": false, "ri_min": 1.64, "ri_max": 1.68, "birefringence": null, "dispersion": null, "sg_min": 1.1, "sg_max": 1.4, "sg_typical": 1.32, "hardness_min": 2.5, "hardness_max": 4, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "nodular" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "opaque" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": null, "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (opaque black organic material absorbs all visible wavelengths)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "kornerupine", "name": "Kornerupine", "species": "Kornerupine", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.66, "ri_max": 1.699, "birefringence": 0.013, "dispersion": 0.018, "sg_min": 3.27, "sg_max": 3.45, "sg_typical": 3.33, "hardness_min": 6.5, "hardness_max": 6.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green", "brown", "yellow_orange" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "brown-yellow", "green" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "variable", "spectroscope_absorption": [ "446 nm — Fe²⁺/Cr³⁺ broad absorption (moderate; chromium-bearing green kornerupine)", "540 nm — Broad absorption region (moderate; Fe/Cr giving green color in some specimens)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "kunzite", "name": "Kunzite", "species": "Spodumene", "variety": "Kunzite", "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.66, "ri_max": 1.676, "birefringence": 0.016, "dispersion": 0.017, "sg_min": 3.15, "sg_max": 3.21, "sg_typical": 3.18, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "red_pink", "purple" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "pink", "violet", "colorless" ], "facet_doubling": false, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "strong_orange", "fluorescence_sw": "moderate_orange", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "553 nm — Mn³⁺ absorption band (moderate; primary diagnostic band for kunzite/spodumene)", "540 nm — Mn³⁺ band (moderate; paired with 553nm gives diagnostic doublet)", "433 nm — Mn absorption shoulder (weak)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "kyanite", "name": "Kyanite", "species": "Kyanite", "variety": null, "crystal_system": "triclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.712, "ri_max": 1.734, "birefringence": 0.016, "dispersion": 0.02, "sg_min": 3.53, "sg_max": 3.68, "sg_typical": 3.68, "hardness_min": 4.5, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "prismatic" ], "luster": [ "vitreous", "pearly" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "blue_violet", "colorless", "green" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "dark blue", "violet-blue" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "447 nm — Fe²⁺ band (moderate; diagnostic iron band most visible in blue kyanite)", "433 nm — Fe²⁺ band (weak)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ], "source_discrepancies": [ { "property": "optic_character", "note": "Kyanite is optically biaxial negative (2V 78–83°) per GIA and standard mineralogy — this is what the app uses. Note that the Gem-A syllabus constants datasheet prints it as biaxial positive (B+); FGA candidates may be graded against that sheet.", "engine_value": "DR_B-", "by_credential": { "gia": { "value": "biaxial negative (B−)", "source": "GIA / mineralogy" }, "fga": { "value": "biaxial positive (B+)", "source": "Gem-A syllabus datasheet" }, "feeg": { "value": "biaxial negative (B−)", "source": "mineralogy" } } } ] }, { "id": "labradorite", "name": "Labradorite", "species": "Feldspar", "variety": "Plagioclase", "crystal_system": "triclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.559, "ri_max": 1.573, "birefringence": 0.011, "dispersion": 0.012, "sg_min": 2.68, "sg_max": 2.75, "sg_typical": 2.7, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "massive" ], "luster": [ "vitreous", "metallic" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "multi", "brown", "black", "blue_violet" ], "pleochroism": "weak", "pleochroic_colors": [ "yellow", "blue", "green" ], "facet_doubling": false, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~418 nm and ~448 nm — two weak, diffuse absorption bands in the violet-blue (weak; Fe³⁺ in tetrahedral Si/Al sites; often too faint for hand spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "lapis_lazuli", "name": "Lapis Lazuli", "species": "Rock", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.5, "ri_max": 1.67, "birefringence": null, "dispersion": null, "sg_min": 2.7, "sg_max": 2.9, "sg_typical": 2.75, "hardness_min": 5, "hardness_max": 6, "cleavage": "indistinct", "fracture_type": "uneven", "crystal_habits": [ "massive" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "opaque" ], "color_categories": [ "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_orange", "fluorescence_sw": "weak_yellow", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Broad S₃·⁻ radical absorption centered near 600 nm in orange region (responsible for blue colour — diagnostic for lazurite; visible as general orange suppression in hand spectroscope)", "Weak secondary absorption near 400 nm in violet region (S₃·⁻ minor band; not always detectable in hand spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "larimar", "name": "Larimar", "species": "Pectolite", "variety": "Larimar (Blue Pectolite)", "crystal_system": "triclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.595, "ri_max": 1.64, "birefringence": 0.04, "dispersion": 0.01, "sg_min": 2.74, "sg_max": 2.9, "sg_typical": 2.8, "hardness_min": 4.5, "hardness_max": 5, "cleavage": "perfect", "fracture_type": "uneven", "crystal_habits": [ "massive", "fibrous", "radiating" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Broad absorption centered near 630 nm in orange region (attributed to Cu²⁺ and/or Fe²⁺–Fe³⁺ intervalence charge transfer — responsible for blue-green colour; no sharp lines visible in hand spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "zircon_low", "name": "Low-Type Zircon", "species": "Zircon", "variety": null, "crystal_system": "tetragonal", "optic_character": "SR", "adr": false, "ri_min": 1.78, "ri_max": 1.815, "birefringence": null, "dispersion": 0.038, "sg_min": 3.9, "sg_max": 4.1, "sg_typical": 4, "hardness_min": 6, "hardness_max": 6, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "tetragonal dipyramidal", "prismatic", "metamict" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "brown", "yellow_orange" ], "pleochroism": "weak", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "653.5 nm — Zircon line (weak to absent; low-type/metamict zircon shows fewer/weaker lines than high-type due to radiation damage)", "659 nm — Zircon line (weak; may be absent in fully metamict specimens)", "Note — Lines progressively weaker as metamictization increases; fully metamict specimens may show no lines" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "malachite", "name": "Malachite", "species": "Malachite", "variety": null, "crystal_system": "monoclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.655, "ri_max": 1.909, "birefringence": 0.254, "dispersion": 0.025, "sg_min": 3.6, "sg_max": 4.05, "sg_typical": 3.8, "hardness_min": 3.5, "hardness_max": 4, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal" ], "luster": [ "vitreous", "silky", "waxy" ], "transparency": [ "opaque" ], "color_categories": [ "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Broad Cu²⁺ absorption centered near 800 nm in near-infrared/deep red region (responsible for green colour; visible as strong red-end suppression in hand spectroscope — no discrete line)", "Absorption cut-off below ~520 nm in blue-violet region (secondary Cu²⁺ band; contributes to green transmission window)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "malaya_garnet", "name": "Malaya / Umbalite Garnet", "species": "Garnet (pyrope-spessartite solid solution)", "variety": "Malaya / Umbalite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.73, "ri_max": 1.78, "birefringence": null, "dispersion": 0.023, "sg_min": 3.65, "sg_max": 3.87, "sg_typical": 3.75, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous", "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "moderate", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": null, "spectroscope_absorption": [ "mn_bands" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "moissanite", "name": "Moissanite", "species": "Silicon Carbide", "variety": null, "crystal_system": "hexagonal", "optic_character": "DR_U+", "adr": false, "ri_min": 2.648, "ri_max": 2.691, "birefringence": 0.043, "dispersion": 0.104, "sg_min": 3.2, "sg_max": 3.22, "sg_typical": 3.22, "hardness_min": 9.25, "hardness_max": 9.25, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "adamantine", "metallic" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "green", "yellow_orange", "blue_violet" ], "pleochroism": "weak", "pleochroic_colors": [ "colorless", "pale bluish-green" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "419 nm — Diagnostic absorption band for synthetic moissanite (SiC)" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "moldavite", "name": "Moldavite", "species": "Silica Glass (tektite)", "variety": "Moldavite", "crystal_system": "amorphous", "optic_character": "SR", "adr": false, "ri_min": 1.48, "ri_max": 1.51, "birefringence": null, "dispersion": 0.01, "sg_min": 2.32, "sg_max": 2.38, "sg_typical": 2.35, "hardness_min": 5.5, "hardness_max": 5.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "irregular_nodules", "splash_form_droplets", "discs" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Broad Fe²⁺/Fe³⁺ diffuse absorption in blue-violet and near-infrared regions (no sharp lines; two vague bands sometimes noted in blue and orange regions with spectrophotometer — not reliably visible in hand spectroscope)", "No diagnostic discrete lines detectable in hand spectroscope — RI (~1.48–1.50) and tektite surface texture are primary tests" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "moonstone", "name": "Moonstone", "species": "Feldspar", "variety": "Orthoclase", "crystal_system": "monoclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.518, "ri_max": 1.526, "birefringence": 0.008, "dispersion": 0.012, "sg_min": 2.56, "sg_max": 2.59, "sg_typical": 2.58, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "massive" ], "luster": [ "vitreous", "pearly" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "colorless", "yellow_orange", "brown", "green", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_blue", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "morganite", "name": "Morganite", "species": "Beryl", "variety": "Morganite", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.572, "ri_max": 1.6, "birefringence": 0.008, "dispersion": 0.014, "sg_min": 2.71, "sg_max": 2.85, "sg_typical": 2.82, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "red_pink", "yellow_orange" ], "pleochroism": "moderate", "pleochroic_colors": [ "pale pink", "deeper bluish-pink" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "weak_orange_pink", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "572 nm — Mn³⁺ absorption band (strong; primary diagnostic band for morganite's pink color)", "540 nm — Mn³⁺ band (moderate; secondary manganese band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "nephrite", "name": "Nephrite", "species": "Nephrite", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.6, "ri_max": 1.627, "birefringence": null, "dispersion": null, "sg_min": 2.9, "sg_max": 3.03, "sg_typical": 2.95, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "none", "fracture_type": "splintery", "crystal_habits": [ "massive" ], "luster": [ "waxy", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "colorless", "black", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Diffuse Fe²⁺ absorption near 430–450 nm in violet-blue region (present in dark green nephrite; weak and broad — visible as blue-end suppression rather than a discrete line)", "Broad Fe²⁺/Fe³⁺ absorption in the 600–730 nm orange-red region (responsible in part for green body colour; not a discrete line — most visible as general red-end suppression)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "obsidian", "name": "Obsidian", "species": "Natural Glass", "variety": null, "crystal_system": "amorphous", "optic_character": "SR", "adr": true, "ri_min": 1.48, "ri_max": 1.51, "birefringence": null, "dispersion": 0.01, "sg_min": 2.3, "sg_max": 2.6, "sg_typical": 2.4, "hardness_min": 5, "hardness_max": 5.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "amorphous", "massive" ], "luster": [ "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "black", "brown", "green", "multi" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "onyx", "name": "Onyx", "species": "Quartz", "variety": "Onyx", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "cryptocrystalline", "banded" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "opaque" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (opaque; black color from carbonized inclusions or dye treatment)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "opal", "name": "Opal", "species": "Opal", "variety": null, "crystal_system": "amorphous", "optic_character": "SR", "adr": false, "ri_min": 1.37, "ri_max": 1.47, "birefringence": null, "dispersion": 0.02, "sg_min": 1.98, "sg_max": 2.25, "sg_typical": 2.15, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "colorless", "yellow_orange", "red_pink", "green", "blue_violet", "black", "multi" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "padparadscha_sapphire", "name": "Padparadscha Sapphire", "species": "Corundum", "variety": "Padparadscha", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.95, "sg_max": 4.03, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange", "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "orangey-pink", "pale orange-yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "moderate_orange_pink", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "450 nm — Fe²⁺ band (moderate; iron contributing to orange component)", "693 nm — Cr³⁺ line (weak; chromium contributing to pink component of padparadscha color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "paraiba_tourmaline", "name": "Paraiba Tourmaline", "species": "Tourmaline", "variety": "Paraiba", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.624, "ri_max": 1.644, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3.02, "sg_max": 3.1, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "acicular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "dark blue-green", "light blue" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "green", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "700 nm+ — Cu²⁺ broad absorption tail (strong; copper causes the neon blue-green color; extends into NIR)", "560 nm — Mn³⁺ broad absorption (strong; manganese absorption band in yellow-green region; reduced or absent after heat treatment)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "pearl", "name": "Pearl", "species": "Organic", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.52, "ri_max": 1.69, "birefringence": null, "dispersion": null, "sg_min": 2.6, "sg_max": 2.85, "sg_typical": 2.74, "hardness_min": 2.5, "hardness_max": 4.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "organic", "spherical", "baroque", "button", "drop" ], "luster": [ "pearly" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "colorless", "red_pink", "yellow_orange", "black", "brown", "green", "blue_violet" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (hand spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "peridot", "name": "Peridot", "species": "Olivine", "variety": "Peridot", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.654, "ri_max": 1.69, "birefringence": 0.036, "dispersion": 0.02, "sg_min": 3.27, "sg_max": 3.48, "sg_typical": 3.34, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green", "yellow_orange" ], "pleochroism": "weak", "pleochroic_colors": [ "yellow-green", "green", "colorless" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "peridot_iron", "493 nm — Fe²⁺ band (strong; the strongest and most visible of the peridot iron trio)", "473 nm — Fe²⁺ band (strong; second band of the diagnostic three-fingered absorption)", "453 nm — Fe²⁺ band (moderate; third band completing the diagnostic trio in the blue-violet region)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "phenakite", "name": "Phenakite", "species": "Phenakite", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.654, "ri_max": 1.67, "birefringence": 0.016, "dispersion": 0.015, "sg_min": 2.95, "sg_max": 2.97, "sg_typical": 2.96, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "rhombohedral", "prismatic", "tabular", "twinned" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": true, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "pietersite", "name": "Pietersite", "species": "Pietersite (brecciated hawk's eye and tiger's eye — crocidolite/quartz aggregate)", "variety": null, "crystal_system": "aggregate", "optic_character": "AGG", "adr": false, "ri_min": 1.534, "ri_max": 1.54, "birefringence": null, "dispersion": null, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "brecciated" ], "luster": [ "silky", "vitreous" ], "transparency": [ "opaque" ], "color_categories": [ "multi", "blue_violet", "brown", "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; Fe absorption from hematite/goethite inclusions diffuse and not resolvable)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "pink_diamond", "name": "Pink Diamond", "species": "Diamond", "variety": "Fancy Pink Diamond", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.417, "ri_max": 2.417, "birefringence": null, "dispersion": 0.044, "sg_min": 3.51, "sg_max": 3.53, "sg_typical": 3.52, "hardness_min": 10, "hardness_max": 10, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "dodecahedral", "cubic" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "n3_415nm", "h3_503nm", "nv_575nm", "nv_637nm" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "pink_sapphire", "name": "Pink Sapphire", "species": "Corundum", "variety": "Pink Sapphire", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.98, "sg_max": 4.01, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "pink", "orange-pink" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "strong_red", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": null, "spectroscope_absorption": [ "694 nm — Cr³⁺ line (moderate to strong; weaker than ruby; present in pink/red sapphire with Cr coloring)", "692 nm — Cr³⁺ companion line (moderate; paired with 694nm)", "476 nm — Cr³⁺ broad absorption (moderate; same as ruby but weaker at lower Cr concentrations)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "prasiolite", "name": "Prasiolite", "species": "Quartz", "variety": "Prasiolite", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.67, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "rhombohedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green" ], "pleochroism": "weak", "pleochroic_colors": [ "pale green", "colorless" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "~720 nm — broad, weak absorption band in the red (Fe²⁺ intervalence charge transfer; responsible for green hue in heat-treated material)", "~550 nm — faint Fe³⁺ absorption band (weak; may be present in natural material)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "prehnite", "name": "Prehnite", "species": "Prehnite", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.611, "ri_max": 1.665, "birefringence": 0.03, "dispersion": 0.02, "sg_min": 2.82, "sg_max": 2.94, "sg_typical": 2.88, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "botryoidal", "stalactitic", "globular" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "transparent" ], "color_categories": [ "green", "yellow_orange", "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~438 nm — weak absorption band in the violet-blue (Fe³⁺ in octahedral Al sites; causes pale green color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "pyrope_garnet", "name": "Pyrope Garnet", "species": "Garnet", "variety": "Pyrope", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.73, "ri_max": 1.76, "birefringence": null, "dispersion": 0.022, "sg_min": 3.62, "sg_max": 3.87, "sg_typical": 3.78, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "moderate", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "505 nm — Fe²⁺ band (moderate; weaker than almandine; primary band of pyrope iron trio)", "527 nm — Fe²⁺ band (moderate; central band)", "575 nm — Fe²⁺ band (moderate; third band; trio less pronounced than almandine)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rainbow_moonstone", "name": "Rainbow Moonstone", "species": "Feldspar", "variety": "White Labradorite (Trade Name: Rainbow Moonstone)", "crystal_system": "triclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.559, "ri_max": 1.572, "birefringence": 0.011, "dispersion": 0.012, "sg_min": 2.68, "sg_max": 2.72, "sg_typical": 2.7, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "uneven", "crystal_habits": [ "tabular", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "colorless" ], "pleochroism": "weak", "pleochroic_colors": [ "colorless", "pale yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "red_beryl", "name": "Red Beryl", "species": "Beryl", "variety": "Bixbite", "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.564, "ri_max": 1.574, "birefringence": 0.007, "dispersion": 0.014, "sg_min": 2.66, "sg_max": 2.7, "sg_typical": 2.68, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "short_prismatic", "small_crystals_typical" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "red", "orange-red" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "mn_absorption_bands" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rhodochrosite", "name": "Rhodochrosite", "species": "Rhodochrosite", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.6, "ri_max": 1.82, "birefringence": 0.22, "dispersion": 0.015, "sg_min": 3.4, "sg_max": 3.7, "sg_typical": 3.5, "hardness_min": 3.5, "hardness_max": 4, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "rhombohedral", "scalenohedral", "massive_stalactitic" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink" ], "pleochroism": "weak", "pleochroic_colors": [ "pink", "pale pink" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "weak_orange", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Mn²⁺ absorption near 410–425 nm in violet region (Fe²⁺/Mn²⁺ crystal-field band; visible in hand spectroscope in deeply coloured specimens)", "Mn²⁺ absorption near 450–460 nm in blue-violet region (second crystal-field band; may appear as broad absorption shoulder)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rhodolite_garnet", "name": "Rhodolite Garnet", "species": "Garnet", "variety": "Rhodolite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.74, "ri_max": 1.77, "birefringence": null, "dispersion": 0.026, "sg_min": 3.74, "sg_max": 3.94, "sg_typical": 3.84, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "red_pink", "purple" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "505 nm — Fe²⁺ band (moderate; pyrope-almandine solid solution shows Fe bands)", "520 nm — Fe²⁺ band (moderate; weaker than pure almandine)", "573 nm — Fe²⁺ band (moderate; less pronounced than almandine trio)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rhodonite", "name": "Rhodonite", "species": "Rhodonite", "variety": null, "crystal_system": "triclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.716, "ri_max": 1.752, "birefringence": 0.014, "dispersion": 0.016, "sg_min": 3.57, "sg_max": 3.76, "sg_typical": 3.6, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "prismatic", "massive", "granular" ], "luster": [ "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink", "brown", "black" ], "pleochroism": "weak", "pleochroic_colors": [ "reddish pink", "yellowish red" ], "facet_doubling": false, "facet_doubling_strength": "moderate", "magnetism": "moderate", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Mn²⁺ absorption near 410 nm in violet region (crystal-field band; analogous to rhodochrosite)", "Mn²⁺ absorption near 503 nm in blue-green region (second Mn²⁺ band; visible in deeply coloured specimens as a diffuse band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rock_crystal", "name": "Rock Crystal", "species": "Quartz", "variety": "Rock Crystal", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.65, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "pyramidal", "striated" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rose_quartz", "name": "Rose Quartz", "species": "Quartz", "variety": "Rose Quartz", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.65, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive" ], "luster": [ "vitreous" ], "transparency": [ "translucent" ], "color_categories": [ "red_pink" ], "pleochroism": "weak", "pleochroic_colors": [ "pale pink", "deep pink" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~500 nm — weak, broad absorption band (Fe-Ti intervalence charge transfer in fibrous inclusions; causes pink color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "rubellite", "name": "Rubellite", "species": "Tourmaline", "variety": "Rubellite", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.624, "ri_max": 1.644, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3.02, "sg_max": 3.1, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated", "columnar" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "dark red", "pale pink" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "524 nm — Mn³⁺ absorption band (strong; primary diagnostic band for rubellite's red-pink color)", "453 nm — Mn³⁺ band (moderate; short wavelength manganese band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "ruby", "name": "Ruby", "species": "Corundum", "variety": "Ruby", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.97, "sg_max": 4.05, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "purplish-red", "orangey-red" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "chromium_doublet", "694.2 nm — Cr³⁺ fluorescence line (strong, diagnostic; the stronger line of the ruby doublet; also visible as emission in fluorescence)", "692.8 nm — Cr³⁺ fluorescence line (strong; paired line of the diagnostic doublet)", "659 nm — Cr³⁺ absorption band (moderate; internal absorption in the red region)", "620 nm — Cr³⁺ broad absorption region (strong; part of broad green/yellow-green absorption band)", "476 nm — Cr³⁺ band (strong; part of broad blue-violet absorption causing complementary red color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "sapphire", "name": "Sapphire", "species": "Corundum", "variety": "Sapphire", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.95, "sg_max": 4.03, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "blue_violet", "red_pink", "yellow_orange", "green", "colorless", "purple", "black", "color_change" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "violet-blue", "greenish-blue" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "inert", "spectroscope_absorption": [ "450 nm — Fe²⁺/Fe³⁺ iron band (strong, primary diagnostic for blue sapphire)", "460 nm — Iron band Fe²⁺ (moderate)", "471 nm — Iron band (moderate, part of diagnostic iron trio)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "scapolite", "name": "Scapolite", "species": "Scapolite (series)", "variety": null, "crystal_system": "tetragonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.54, "ri_max": 1.572, "birefringence": 0.02, "dispersion": 0.017, "sg_min": 2.5, "sg_max": 2.74, "sg_typical": 2.63, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous", "resinous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "colorless", "yellow_orange", "purple", "blue_violet" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "colorless", "violet" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "strong_orange", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "663 nm — Mn²⁺ band (moderate; present in purple/violet scapolite; manganese coloration)", "652 nm — Mn²⁺ band (moderate; paired with 663nm)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "serpentine", "name": "Serpentine", "species": "Serpentine (Mg₃Si₂O₅(OH)₄)", "variety": null, "crystal_system": "monoclinic", "optic_character": "AGG", "adr": false, "ri_min": 1.56, "ri_max": 1.571, "birefringence": null, "dispersion": null, "sg_min": 2.44, "sg_max": 2.62, "sg_typical": 2.55, "hardness_min": 3, "hardness_max": 6, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [], "luster": [ "waxy", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green", "yellow_orange", "brown", "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~450 nm — weak, broad absorption band in the blue-violet (Fe³⁺ from oxidized structural Fe²⁺)", "~570 nm — weak, broad absorption band in the yellow-green (Fe³⁺; contributes to green body color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "ODONOGHUE_2006", "SCHUMANN_2017" ] }, { "id": "sinhalite", "name": "Sinhalite", "species": "Sinhalite (MgAlBO₄)", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.665, "ri_max": 1.712, "birefringence": 0.038, "dispersion": 0.018, "sg_min": 3.47, "sg_max": 3.5, "sg_typical": 3.48, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "brown", "yellow_orange", "green" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "pale brown", "dark brown", "greenish-brown" ], "facet_doubling": true, "facet_doubling_strength": "strong", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "452 nm — absorption band", "475 nm — absorption band", "493 nm — absorption band" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2017" ] }, { "id": "smoky_quartz", "name": "Smoky Quartz", "species": "Quartz", "variety": "Smoky Quartz", "crystal_system": "trigonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": 0.009, "dispersion": 0.013, "sg_min": 2.63, "sg_max": 2.65, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "pyramidal", "striated" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "brown", "black" ], "pleochroism": "weak", "pleochroic_colors": [ "brown", "grayish brown" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic visible bands — spectrum featureless (color from Al/H color centers; no sharp spectroscope lines visible in standard gemological spectroscope)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "sodalite", "name": "Sodalite", "species": "Sodalite", "variety": null, "crystal_system": "cubic", "optic_character": "AGG", "adr": false, "ri_min": 1.483, "ri_max": 1.487, "birefringence": null, "dispersion": null, "sg_min": 2.14, "sg_max": 2.4, "sg_typical": 2.27, "hardness_min": 5.5, "hardness_max": 6, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "massive", "granular" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "opaque", "translucent" ], "color_categories": [ "blue_violet", "colorless" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~675 nm — step-shaped absorption in the red (S²⁻/S³⁻ sulfide cluster electronic transition; contributes to royal blue color)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "spessartite_garnet", "name": "Spessartite Garnet", "species": "Garnet", "variety": "Spessartite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.79, "ri_max": 1.815, "birefringence": null, "dispersion": 0.027, "sg_min": 4.12, "sg_max": 4.18, "sg_typical": 4.15, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "trapezohedron", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "moderate", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "432 nm — Mn²⁺ absorption band (strong; primary diagnostic band, most prominent in spessartite)", "420 nm — Mn²⁺ band (strong; short wavelength manganese band)", "412 nm — Mn²⁺ band (moderate; part of distinctive blue-violet Mn absorption group)", "504 nm — Fe²⁺ band (moderate; if Fe-bearing spessartite; pyrope-spessartite solid solution)", "520 nm — Fe²⁺ band (moderate; secondary iron band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "sphalerite", "name": "Sphalerite", "species": "Sphalerite", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 2.369, "ri_max": 2.371, "birefringence": null, "dispersion": 0.156, "sg_min": 3.9, "sg_max": 4.1, "sg_typical": 4.09, "hardness_min": 3.5, "hardness_max": 4, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tetrahedral", "dodecahedral", "massive", "granular", "twinned" ], "luster": [ "adamantine", "resinous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "brown", "red_pink", "green", "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Fe²⁺ crystal-field band near 669–671 nm in red region (strong; clearly visible in hand spectroscope — diagnostic for sphalerite)", "Fe²⁺ crystal-field band near 698–702 nm in deep red region (strong; part of the diagnostic triplet)", "Fe²⁺ crystal-field band near 732–743 nm in deep red/near-infrared region (strong; third member of the Fe²⁺ triplet — note: attributed to Fe²⁺, not Cd²⁺ as older literature stated)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "sphene", "name": "Sphene", "species": "Titanite", "variety": "Sphene", "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.843, "ri_max": 2.11, "birefringence": 0.1, "dispersion": 0.051, "sg_min": 3.45, "sg_max": 3.55, "sg_typical": 3.53, "hardness_min": 5, "hardness_max": 5.5, "cleavage": "distinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "adamantine" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "green", "yellow_orange", "brown" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "colorless", "yellow-green", "reddish-brown" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "586 nm — Fe³⁺ band (strong; primary diagnostic iron band for sphene/titanite)", "532 nm — Fe³⁺ band (moderate)", "497 nm — Fe³⁺ band (moderate; part of the distinctive sphene iron absorption group)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "spinel", "name": "Spinel", "species": "Spinel", "variety": null, "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.712, "ri_max": 1.736, "birefringence": null, "dispersion": 0.02, "sg_min": 3.57, "sg_max": 3.63, "sg_typical": 3.6, "hardness_min": 7.5, "hardness_max": 8, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "red_pink", "blue_violet", "purple", "black", "colorless", "green", "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "variable", "spectroscope_absorption": [ "685 nm — Cr³⁺ doublet (strong, red/pink natural spinel)", "684 nm — Cr³⁺ doublet companion (strong, red/pink natural spinel)", "533 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)", "580 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)", "619 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "star_diopside", "name": "Star Diopside", "species": "Diopside", "variety": "Black Star Diopside", "crystal_system": "monoclinic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.664, "ri_max": 1.721, "birefringence": 0.03, "dispersion": 0.013, "sg_min": 3.27, "sg_max": 3.36, "sg_typical": 3.29, "hardness_min": 5, "hardness_max": 6, "cleavage": "distinct", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "black" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "505 nm — Fe²⁺/Fe³⁺ absorption band (moderate; iron absorption in diopside)", "508 nm — Fe²⁺ band (moderate; diagnostic for iron-bearing diopside)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "star_garnet", "name": "Star Garnet", "species": "Garnet", "variety": "Star Almandine", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.77, "ri_max": 1.83, "birefringence": null, "dispersion": 0.024, "sg_min": 3.93, "sg_max": 4.3, "sg_typical": 4.05, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral", "rhombohedral" ], "luster": [ "vitreous", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink", "purple", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "strong", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "almandite_trio" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "star_ruby", "name": "Star Ruby", "species": "Corundum", "variety": "Star Ruby", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.97, "sg_max": 4.05, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "purplish-red", "orangey-red" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "694.2 nm — Cr³⁺ fluorescence line (strong; same as ruby; primary doublet line)", "692.8 nm — Cr³⁺ fluorescence line (strong; paired doublet line)", "476 nm — Cr³⁺ broad absorption (strong; blue-violet region absorption same as ruby)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "star_sapphire", "name": "Star Sapphire", "species": "Corundum", "variety": "Star Sapphire", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.95, "sg_max": 4.03, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous", "silky" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "blue_violet", "black", "colorless", "purple", "red_pink", "yellow_orange" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "violet-blue", "greenish-blue" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "450 nm — Fe²⁺/Fe³⁺ iron band (moderate; same as blue sapphire; diagnostic for blue star sapphire)", "460 nm — Fe²⁺ band (moderate)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "sugilite", "name": "Sugilite", "species": "Sugilite", "variety": null, "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.607, "ri_max": 1.61, "birefringence": 0.002, "dispersion": 0.01, "sg_min": 2.74, "sg_max": 2.8, "sg_typical": 2.76, "hardness_min": 5.5, "hardness_max": 6.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "massive" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "purple" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Broad Mn³⁺ absorption envelope centered near 560 nm spanning approximately 500–700 nm (responsible for violet-purple colour; visible in hand spectroscope as broad green-yellow suppression)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "sunstone", "name": "Sunstone", "species": "Feldspar", "variety": "Plagioclase (Oligoclase / Andesine)", "crystal_system": "triclinic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.537, "ri_max": 1.572, "birefringence": 0.01, "dispersion": 0.012, "sg_min": 2.62, "sg_max": 2.65, "sg_typical": 2.63, "hardness_min": 6, "hardness_max": 6.5, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "tabular", "massive" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent" ], "color_categories": [ "yellow_orange", "red_pink", "colorless", "green" ], "pleochroism": "weak", "pleochroic_colors": [ "pale yellow", "orange-red", "colorless" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "weak_orange", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "~560–590 nm — broad absorption band (localized surface plasmon resonance of copper nanoparticle inclusions; causes red-orange to green colors in Oregon sunstone)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "synthetic_color_change_corundum", "name": "Synthetic Color-Change Corundum", "species": "Corundum (synthetic)", "variety": "Color-Change Vanadium Corundum", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.97, "sg_max": 4.05, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "boule" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "color_change", "blue_violet", "red_pink", "purple" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "purple-blue", "purple-red" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "strong_red", "fluorescence_sw": "strong_red", "chelsea_filter": "red", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "693 nm — Cr³⁺ line (strong; vanadium and chromium dopants used to create blue-to-red color change)", "450 nm — Fe²⁺/V³⁺ band (strong; causes absorption of visible blue-green in combination with Cr/V)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "synthetic_spinel", "name": "Synthetic Spinel", "species": "Spinel (synthetic)", "variety": "Flame Fusion (Verneuil)", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.725, "ri_max": 1.728, "birefringence": null, "dispersion": 0.02, "sg_min": 3.61, "sg_max": 3.66, "sg_typical": 3.63, "hardness_min": 8, "hardness_max": 8, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "boule" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "red_pink", "colorless", "green", "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "strong_blue_white", "fluorescence_sw": "strong_blue_white", "chelsea_filter": "red", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Co²⁺ absorption band near 540–545 nm in green region (strong; part of cobalt triplet — diagnostic for cobalt-coloured synthetic spinel)", "Co²⁺ absorption band near 580 nm in yellow-green region (strong; second member of diagnostic cobalt triplet)", "Co²⁺ absorption band near 625–635 nm in orange-red region (strong; third member of diagnostic cobalt triplet — the triplet as a whole is essentially diagnostic for Co-doped synthetic spinel vs natural iron-blue spinel)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "taaffeite", "name": "Taaffeite", "species": "Taaffeite", "variety": null, "crystal_system": "hexagonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.719, "ri_max": 1.723, "birefringence": 0.004, "dispersion": 0.019, "sg_min": 3.59, "sg_max": 3.63, "sg_typical": 3.61, "hardness_min": 8, "hardness_max": 8.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "red_pink", "purple", "blue_violet", "green" ], "pleochroism": "weak", "pleochroic_colors": [ "pink", "colorless" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "Iron-bearing specimens may show absorption similar to iron-bearing spinel (broad Fe²⁺ band 400–590 nm)", "Chromium-rich specimens show absorption band ~550 nm" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "tanzanite", "name": "Tanzanite", "species": "Zoisite", "variety": "Tanzanite", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.691, "ri_max": 1.7, "birefringence": 0.009, "dispersion": 0.03, "sg_min": 3.35, "sg_max": 3.38, "sg_typical": 3.35, "hardness_min": 6, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "purple" ], "pleochroism": "strong_trichroic", "pleochroic_colors": [ "blue", "violet", "burgundy" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "weak_red_brown", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "595 nm — V³⁺/Ti³⁺ absorption band (strong; vanadium/titanium causing the blue-violet color)", "528 nm — V³⁺ band (moderate; vanadium absorption in green-yellow region)", "455 nm — V³⁺ band (moderate; short wavelength vanadium band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "thulite", "name": "Thulite", "species": "Zoisite", "variety": "Thulite (Manganese-Bearing Pink Zoisite)", "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.691, "ri_max": 1.704, "birefringence": 0.009, "dispersion": 0.012, "sg_min": 3.1, "sg_max": 3.38, "sg_typical": 3.2, "hardness_min": 6, "hardness_max": 7, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "massive" ], "luster": [ "vitreous", "waxy" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "red_pink" ], "pleochroism": "weak", "pleochroic_colors": [ "pink", "pale pink", "colorless" ], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Mn³⁺ absorption near 455 nm in violet-blue region (crystal-field band; visible in hand spectroscope in deeply coloured specimens)", "Mn³⁺ absorption near 560–580 nm in yellow-green region (second Mn³⁺ band; responsible for pink colour by subtracting green from white light)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "tigers_eye", "name": "Tiger's Eye", "species": "Quartz", "variety": "Tiger's Eye", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.544, "ri_max": 1.553, "birefringence": null, "dispersion": 0.013, "sg_min": 2.64, "sg_max": 2.71, "sg_typical": 2.65, "hardness_min": 7, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "fibrous", "massive", "silicified" ], "luster": [ "silky", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "yellow_orange", "brown" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "weak", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; diffuse Fe³⁺/limonite absorption not resolvable into lines)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "topaz", "name": "Topaz", "species": "Topaz", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B+", "adr": false, "ri_min": 1.609, "ri_max": 1.643, "birefringence": 0.008, "dispersion": 0.014, "sg_min": 3.49, "sg_max": 3.57, "sg_typical": 3.53, "hardness_min": 8, "hardness_max": 8, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "yellow_orange", "red_pink", "brown", "colorless" ], "pleochroism": "moderate", "pleochroic_colors": [ "colorless", "pale blue", "pink" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands — spectrum generally featureless (most topaz colors arise from color centers or trace elements without sharp spectroscope absorption)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "tourmaline", "name": "Tourmaline", "species": "Tourmaline", "variety": null, "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.624, "ri_max": 1.644, "birefringence": 0.02, "dispersion": 0.017, "sg_min": 3.01, "sg_max": 3.26, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "acicular" ], "luster": [ "vitreous" ], "transparency": [ "transparent", "translucent", "opaque" ], "color_categories": [ "red_pink", "green", "blue_violet", "yellow_orange", "brown", "black", "colorless", "multi" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "variable", "hanneman_filter": "variable", "spectroscope_absorption": [ "Variable by color — Fe²⁺ bands in green/blue varieties; Mn³⁺ bands in pink/red; Cr³⁺ bands in chrome tourmaline; Cu²⁺ bands in Paraiba" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "tsavorite_garnet", "name": "Tsavorite Garnet", "species": "Garnet", "variety": "Tsavorite", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 1.73, "ri_max": 1.76, "birefringence": null, "dispersion": 0.028, "sg_min": 3.59, "sg_max": 3.65, "sg_typical": 3.61, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "dodecahedral" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "red", "hanneman_filter": "red", "spectroscope_absorption": [ "438 nm — V³⁺ broad absorption band (strong; primary vanadium band causing absorption of violet and transmission of green; diagnostic for vanadium-colored tsavorite)", "610 nm — V³⁺ absorption band (moderate; secondary vanadium band in orange-red region; part of the diagnostic V³⁺ absorption pair with 438 nm)", "630 nm — Cr³⁺ absorption line (moderate; chromium doublet band present in high-Cr tsavorites; forms pair with ~690 nm band)", "690 nm — Cr³⁺ absorption line (moderate; red-region chromium band present in Cr-bearing tsavorites; note: 701 nm is an Fe³⁺ band characteristic of andradite/demantoid and does NOT occur in tsavorite)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "turquoise", "name": "Turquoise", "species": "Turquoise", "variety": null, "crystal_system": "triclinic", "optic_character": "AGG", "adr": false, "ri_min": 1.61, "ri_max": 1.65, "birefringence": null, "dispersion": null, "sg_min": 2.6, "sg_max": 2.9, "sg_typical": 2.76, "hardness_min": 5, "hardness_max": 6, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal" ], "luster": [ "waxy" ], "transparency": [ "opaque" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_blue_white", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Cu²⁺ absorption band near 432 nm in violet-blue region (strong; diagnostic — visible in hand spectroscope; most reliable hand-instrument test for copper content)", "Cu²⁺ absorption band near 460 nm in blue-violet region (weak; secondary band, sometimes visible as shoulder on the 432 nm feature)", "Fe³⁺ absorption near 689 nm in red region (present in iron-bearing specimens only; absent in pure Cu turquoise — useful to distinguish greenish Fe-rich material from blue Cu-rich material)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "variscite", "name": "Variscite", "species": "Variscite", "variety": null, "crystal_system": "orthorhombic", "optic_character": "DR_B-", "adr": false, "ri_min": 1.56, "ri_max": 1.594, "birefringence": 0.031, "dispersion": 0.016, "sg_min": 2.4, "sg_max": 2.6, "sg_typical": 2.52, "hardness_min": 3.5, "hardness_max": 4.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "nodular", "reniform" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "weak_green", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "Cr³⁺ absorption doublet with bands near 645 nm and 690 nm in orange-red region (visible in hand spectroscope — similar pattern to emerald; supports Cr³⁺ as chromophore)", "Broad Cr³⁺ absorption near 430–450 nm in violet region (responsible for absorbing violet, contributing to green transmission)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "watermelon_tourmaline", "name": "Watermelon Tourmaline", "species": "Tourmaline", "variety": "Elbaite (Bicolor)", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.616, "ri_max": 1.65, "birefringence": 0.018, "dispersion": 0.017, "sg_min": 3, "sg_max": 3.1, "sg_typical": 3.06, "hardness_min": 7, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "striated_prism_faces", "trigonal_cross_section", "commonly_sliced_perpendicular_to_c_axis" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "multi", "red_pink", "green" ], "pleochroism": "strong_dichroic", "pleochroic_colors": [ "pink", "green" ], "facet_doubling": true, "facet_doubling_strength": "moderate", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "variable_fe_in_green_zone", "mn_in_pink_zone" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "white_sapphire", "name": "White Sapphire", "species": "Corundum", "variety": "White Sapphire (Colorless Corundum)", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.99, "sg_max": 4.01, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "colorless" ], "pleochroism": "weak", "pleochroic_colors": [ "colorless", "faint grayish-white" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "No strong diagnostic bands — white/colorless sapphire typically shows clean spectrum (no Fe or Cr color centers in colorless corundum)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "yag", "name": "YAG", "species": "Synthetic Garnet", "variety": "Yttrium Aluminum Garnet", "crystal_system": "cubic", "optic_character": "SR", "adr": false, "ri_min": 1.833, "ri_max": 1.833, "birefringence": null, "dispersion": 0.028, "sg_min": 4.5, "sg_max": 4.6, "sg_typical": 4.55, "hardness_min": 8, "hardness_max": 8.5, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "boule" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "colorless", "yellow_orange", "green", "blue_violet", "red_pink" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "inert", "fluorescence_sw": "inert", "chelsea_filter": "not_applicable", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "No diagnostic absorption bands in colorless YAG — clean featureless spectrum (undoped YAG has no chromophores)", "Colored YAG (doped): Er³⁺ at 450nm+, Nd³⁺ at 578nm, Cr³⁺ at 689nm depending on dopant used" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "yellow_diamond", "name": "Yellow Diamond", "species": "Diamond", "variety": "Fancy Yellow Diamond", "crystal_system": "cubic", "optic_character": "SR", "adr": true, "ri_min": 2.417, "ri_max": 2.417, "birefringence": null, "dispersion": 0.044, "sg_min": 3.51, "sg_max": 3.53, "sg_typical": 3.52, "hardness_min": 10, "hardness_max": 10, "cleavage": "perfect", "fracture_type": "conchoidal", "crystal_habits": [ "octahedral", "dodecahedral", "cubic" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "variable", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "n3_415nm", "cape_452nm", "cape_465nm", "h3_503nm" ], "thermal_test": "diamond", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "yellow_sapphire", "name": "Yellow Sapphire", "species": "Corundum", "variety": "Yellow Sapphire", "crystal_system": "trigonal", "optic_character": "DR_U-", "adr": false, "ri_min": 1.762, "ri_max": 1.77, "birefringence": 0.008, "dispersion": 0.018, "sg_min": 3.99, "sg_max": 4.01, "sg_typical": 4, "hardness_min": 9, "hardness_max": 9, "cleavage": "none", "fracture_type": "uneven", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "vitreous" ], "transparency": [ "transparent" ], "color_categories": [ "yellow_orange" ], "pleochroism": "weak", "pleochroic_colors": [ "yellow", "pale yellow" ], "facet_doubling": false, "facet_doubling_strength": "weak", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": null, "spectroscope_absorption": [ "450 nm — Fe²⁺ band (weak to moderate; Fe-colored yellow sapphire may show this band; absent in Be-diffused material)", "460 nm — Fe²⁺ band (weak; secondary iron band)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013", "HUGHES_2017" ] }, { "id": "zircon", "name": "Zircon", "species": "Zircon", "variety": null, "crystal_system": "tetragonal", "optic_character": "DR_U+", "adr": false, "ri_min": 1.925, "ri_max": 1.984, "birefringence": 0.059, "dispersion": 0.039, "sg_min": 4.6, "sg_max": 4.8, "sg_typical": 4.69, "hardness_min": 7.5, "hardness_max": 7.5, "cleavage": "indistinct", "fracture_type": "conchoidal", "crystal_habits": [ "prismatic", "tabular" ], "luster": [ "adamantine" ], "transparency": [ "transparent" ], "color_categories": [ "blue_violet", "brown", "green", "yellow_orange", "red_pink", "colorless" ], "pleochroism": "moderate", "pleochroic_colors": [ "blue", "colorless" ], "facet_doubling": true, "facet_doubling_strength": "extreme", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "not_applicable", "spectroscope_absorption": [ "line_653", "653.5 nm — Diagnostic zircon line (strong; the most distinctive zircon band, visible in most high-type specimens)", "659 nm — Zircon line (moderate; closely spaced with 653.5nm; together form a distinctive pair)", "621 nm — Zircon absorption line (moderate)", "615 nm — Zircon absorption line (moderate)", "589 nm — Zircon line (weak to moderate)", "562 nm — Zircon line (weak; part of the characteristic 'staircase' spectrum)", "537 nm — Zircon line (weak)", "516 nm — Zircon line (weak; staircase pattern continues)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] }, { "id": "chrysocolla_chalcedony", "name": "Chrysocolla Chalcedony", "species": "Quartz", "variety": "Chrysocolla Chalcedony", "crystal_system": "trigonal", "optic_character": "AGG", "adr": false, "ri_min": 1.53, "ri_max": 1.543, "birefringence": null, "dispersion": 0.013, "sg_min": 2.58, "sg_max": 2.64, "sg_typical": 2.61, "hardness_min": 6.5, "hardness_max": 7, "cleavage": "none", "fracture_type": "conchoidal", "crystal_habits": [ "massive", "botryoidal", "cryptocrystalline" ], "luster": [ "waxy", "vitreous" ], "transparency": [ "translucent", "opaque" ], "color_categories": [ "blue_violet", "green" ], "pleochroism": "none", "pleochroic_colors": [], "facet_doubling": false, "facet_doubling_strength": "none", "magnetism": "none", "fluorescence_lw": "variable", "fluorescence_sw": "inert", "chelsea_filter": "inert", "hanneman_filter": "inert", "spectroscope_absorption": [ "Broad Cu²⁺ absorption centered near 700–800 nm in orange-red region (responsible for blue-green colour transmission; visible as general red suppression rather than a discrete line)" ], "thermal_test": "simulant", "sources": [ "ANDERSON_1990", "GIA_REF_1995", "ODONOGHUE_2006", "SCHUMANN_2013" ] } ] }