Prasiolite

Physical & Optical Properties

RI Range1.544–1.553

SG Range2.63–2.67

SG Typical2.65

Hardness (Mohs)7

Crystal SystemTrigonal

Optic CharacterDR Uniaxial (+)

Birefringence0.009

Dispersion0.013

Fluorescence LWInert

Fluorescence SWInert

Chelsea FilterInert

PleochroismWeak

ColorsGreen

SpeciesQuartz

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

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: Green Tourmaline, Peridot.

Natural — low ($/ct)$10

Natural — high ($/ct)$80

NotePer carat; low value due to abundance of treated material; clean well-cut stones $20–80/ct

Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.

Identifying a prasiolite? GemID walks through these tests in order — RI, SG, fluorescence, and more.