Sinhalite
Sinhalite is a rare borate mineral first described as a gem species in 1952 (originally misidentified as a brown peridot variety). It is still frequently misidentified as peridot, brown tourmaline, or zircon. The diagnostic triple absorption bands at 452, 475, and 493 nm in the spectroscope (Anderson 1990) are the definitive test. The high birefringence (0.038) produces strong facet doubling visible under 10× loupe.
Physical & Optical Properties
Key Differentiators
- Diagnostic spectroscope absorption bands at 452, 475, and 493 nm — essentially unique to sinhalite
- Strong facet doubling visible under 10× loupe (birefringence 0.038)
- RI 1.665–1.712 with biaxial negative optic sign
- SG 3.47–3.50 — heavier than peridot (3.28–3.48)
- Distinct trichroism: pale brown / dark brown / greenish brown
Commonly Confused With
Commonly confused with: Peridot.
Price Context
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Sinhalite
Sinhalite is a rare borate mineral first described as a gem species in 1952 (originally misidentified as a brown peridot variety). It is still frequently misidentified as peridot, brown tourmaline, or zircon. The diagnostic triple absorption bands at 452, 475, and 493 nm in the spectroscope (Anderson 1990) are the definitive test. The high birefringence (0.038) produces strong facet doubling visible under 10× loupe.
Identifying a sinhalite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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