Refractive Index Calculator
Interpret RI measurement and birefringence for gemstone identification against a reference database.
Inputs
Results
Best Match
Amethyst/Quartz
All MatchesAmethyst/Quartz
Optic CharacterAnisotropic (DR)
RI Low1.54
RI High1.55
Birefringence0.01
How to Use This Calculator
- Place the gemstone on a refractometer and record the RI Reading from the shadow edge.
- If the stone shows birefringence, record both readings to calculate the Birefringence value.
- Review the Best Match — the gem identification most consistent with your RI reading.
- Check All Matches to see other possibilities within the RI range.
- Use Optic Character (isotropic vs anisotropic) to narrow identification further.
What each input means
- RI Reading
- Refractive index reading from refractometer
- Birefringence
- Difference between high and low RI readings (0 for isotropic)
How this is calculated
Worked example, using the default values
- Identify Input ParametersRI Reading = 1.544, Birefringence = 0.009 = 2 input(s) provided
- Calculate Best MatchBest MatchAmethyst/Quartz = Amethyst/Quartz
- Calculate All MatchesAll MatchesAmethyst/Quartz = Amethyst/Quartz
- Calculate Optic CharacterOptic CharacterAnisotropic (DR) = Anisotropic (DR)
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