Prasiolite
Last updated: April 2026
Prasiolite is the pale green variety of quartz produced commercially by heat-treating or irradiating amethyst from Brazil. Naturally occurring prasiolite is extremely rare. The color is typically a gentle leek-green or mint and lacks the intensity of tourmaline or peridot.
Prasiolite has a specific gravity of 2.65 and a refractive index of 1.544–1.553, with a Mohs hardness of 7. It is uniaxial +.
Physical & Optical Properties
Related: Quartz Varieties
Key Differentiators
- Pale leek-green to mint green color distinct from deeper greens of tourmaline or peridot
- Quartz RI 1.544–1.553 and SG 2.65 — much lighter than peridot (SG 3.34) or tourmaline
- Weak pleochroism (pale green / colorless)
- All commercial material is heat-treated or irradiated amethyst — color may fade under prolonged UV
- Inert UV fluorescence in both LW and SW
Common Simulants
- Green Tourmaline: Tourmaline has much higher RI (1.624–1.644) and strong dichroism. SG 3.06 vs prasiolite 2.65. Color is typically more saturated. RI separates cleanly.
- Peridot: Peridot RI 1.654–1.690, SG 3.34 — significantly heavier and higher RI. Birefringence 0.036 means facet doubling visible under loupe. Strong yellowish-green color.
- Green Beryl: Green beryl RI 1.577–1.583, SG 2.72 — slightly higher RI and SG than prasiolite quartz. Uniaxial negative vs prasiolite uniaxial positive.
- Green Glass: Glass is singly refractive (isotropic), may have gas bubbles or swirl marks under magnification. RI variable but no birefringence.
Commonly Confused With
Commonly confused with: Green Tourmaline, Peridot.
Treatments
- Heat Treatment (amethyst → green)
- Irradiation (amethyst → green)
Price Context
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a prasiolite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →Studying for the GIA, FGA, or FEEG practical? Prasiolite is one of the 130 species in GemID’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
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