Gemstones with RI 1.880
3 gemstones have a refractive index range that includes 1.880. 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 |
|---|---|---|---|---|
| Demantoid Garnet | 1.880 – 1.895 | 3.82 – 3.88 | Cubic | SR |
| Sphene | 1.843 – 2.110 | 3.45 – 3.55 | Monoclinic | DR_B+ |
| Malachite | 1.655 – 1.909 | 3.60 – 4.05 | Monoclinic | DR_B- |