Gemstones with RI 2.010
2 gemstones have a refractive index range that includes 2.010. 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 |
|---|---|---|---|---|
| Sphene | 1.843 – 2.110 | 3.45 – 3.55 | Monoclinic | DR_B+ |
| Cassiterite | 2.010 – 2.100 | 6.80 – 7.10 | Tetragonal | DR_U+ |