Chrome Diopside
Last updated: August 2026
Vivid grass-green chromium-bearing diopside sourced primarily from Russia/Siberia. Chelsea filter shows red (chromium coloring). Hardness 5.5–6.5 makes it vulnerable to abrasion in rings. Distinguished from emerald by lower RI; from tsavorite by lower SG.
Chrome Diopside has a specific gravity of 3.30 and a refractive index of 1.664–1.730, with a Mohs hardness of 5.5–6.5. It is biaxial +.
Physical & Optical Properties
Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.
Through the refractometer
Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.
Key Differentiators
- Chelsea filter red — chromium coloring (confirms Cr; does not distinguish from emerald without RI)
- RI 1.664–1.730 — higher than emerald (1.565–1.602) but lower than tsavorite (1.730–1.760)
- Low hardness 5.5–6.5 — easily scratched, unlike emerald (7.5–8) or tsavorite (7–7.5)
- SG 3.22–3.38 — lower than tsavorite (3.59–3.65)
- Biaxial negative; moderate facet doubling
Common Simulants
- Emerald: Emerald is uniaxial negative; RI 1.565–1.602; SG 2.72; typically has characteristic "jardin" inclusions.
- Tsavorite Garnet: Isotropic SR; RI 1.740; SG 3.61; no doubling under loupe; vivid green without blue tone.
Commonly Confused With
Commonly confused with: Emerald, Tsavorite Garnet.
Measurement Guides
Identifying a chrome diopside? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Chrome Diopside is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →