Diaspore
Last updated: April 2026
Color-change diaspore marketed as Zultanite or Csarite shifts from kiwi green in daylight to champagne/pink in incandescent light. Commercially sourced almost exclusively from Turkey. Distinct from alexandrite: color shift is green-to-champagne rather than green-to-red. High birefringence (0.048) causes moderate facet doubling visible under 10x loupe.
Diaspore has a specific gravity of 3.35 and a refractive index of 1.702–1.752, with a Mohs hardness of 6.5–7.0. 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
- Color change: green (daylight) → champagne/pink (incandescent) — distinct from alexandrite green-to-red
- High birefringence 0.048 — moderate facet doubling visible at 10x
- Strong trichroism: colorless / pale yellow-green / pink-champagne
- RI 1.702–1.752 (wide spread due to high birefringence)
- Commercially sourced almost exclusively from Turkey
Commonly Confused With
Commonly confused with: Alexandrite.
Treatments
- Heat Treatment (brownish tone reduction)
Measurement Guides
Identifying a diaspore? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Diaspore 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 →