Gemstones with RI 1.540
16 gemstones have a refractive index range that includes 1.540. Refractive index measures how much light bends when entering a gem — it's one of the most diagnostic properties for identification. Measured with a gemological refractometer.
| Gemstone | RI Range | SG Range | Crystal System | Optic Character |
|---|---|---|---|---|
| Iolite | 1.535 – 1.547 | 2.57 – 2.66 | Orthorhombic | DR_B- |
| Amber | 1.539 – 1.545 | 1.05 – 1.09 | Amorphous | SR |
| Ivory | 1.535 – 1.540 | 1.70 – 1.98 | Aggregate | AGG |
| Pietersite | 1.534 – 1.540 | 2.58 – 2.64 | Aggregate | AGG |
| Agate | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Bloodstone | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Carnelian | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Chalcedony | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Chrysoprase | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Onyx | 1.530 – 1.543 | 2.58 – 2.64 | Trigonal | AGG |
| Chrysocolla | 1.460 – 1.630 | 2.00 – 2.40 | Amorphous | AGG |
| Sunstone | 1.537 – 1.572 | 2.62 – 2.65 | Triclinic | DR_B- |
| Scapolite | 1.540 – 1.572 | 2.50 – 2.74 | Tetragonal | DR_U- |
| Coral | 1.486 – 1.658 | 2.60 – 2.70 | Aggregate | AGG |
| Lapis Lazuli | 1.500 – 1.670 | 2.70 – 2.90 | Aggregate | AGG |
| Pearl | 1.520 – 1.690 | 2.60 – 2.85 | Aggregate | AGG |