Sphalerite
Last updated: April 2026
A zinc sulfide mineral with dispersion more than three times that of diamond, but is too soft for most jewelry.
Sphalerite has a specific gravity of 4.09 and a refractive index of 2.369–2.500, with a Mohs hardness of 3.5–4.0. It is singly refractive.
Physical & Optical Properties
RI Range2.369–2.500
SG Range3.90–4.10
SG Typical4.09
Hardness (Mohs)3.5–4
Crystal SystemCubic
Optic CharacterSR (Singly Refractive)
Dispersion0.156
Fluorescence LWVariable
Fluorescence SWVariable
Chelsea FilterInert
PleochroismNone
ColorsYellow Orange, Brown, Red Pink, Green, Black
SpeciesSphalerite
Key Differentiators
- Extraordinarily high dispersion
- Low hardness
- Perfect dodecahedral cleavage
Price Context
Natural — low ($/ct)$30
Natural — high ($/ct)$300
NotePer carat; rare collector gem; extreme dispersion exceeds diamond; very soft and fragile
Price context is approximate. Loupewise is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a sphalerite? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Sphalerite is one of the 130 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →