Gemstones with RI 1.830
3 gemstones have a refractive index range that includes 1.830. 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 |
|---|---|---|---|---|
| Almandine Garnet | 1.770 – 1.830 | 3.93 – 4.30 | Cubic | SR |
| Star Garnet | 1.770 – 1.830 | 3.93 – 4.30 | Cubic | SR |
| Malachite | 1.655 – 1.909 | 3.60 – 4.05 | Monoclinic | DR_B- |