Gemstones with RI 1.725
9 gemstones have a refractive index range that includes 1.725. 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 |
|---|---|---|---|---|
| Spinel | 1.712 – 1.736 | 3.57 – 3.63 | Cubic | SR |
| Synthetic Spinel | 1.725 – 1.728 | 3.52 – 3.65 | Cubic | SR |
| Kyanite | 1.712 – 1.734 | 3.53 – 3.68 | Triclinic | DR_B- |
| Black Spinel | 1.712 – 1.730 | 3.58 – 3.61 | Cubic | SR |
| Diaspore | 1.685 – 1.752 | 3.30 – 3.39 | Orthorhombic | DR_B+ |
| Rhodonite | 1.716 – 1.752 | 3.57 – 3.76 | Triclinic | DR_B+ |
| Rhodochrosite | 1.600 – 1.820 | 3.40 – 3.70 | Trigonal | DR_U- |
| Chrome Diopside | 1.664 – 1.730 | 3.22 – 3.38 | Monoclinic | DR_B- |
| Malachite | 1.655 – 1.909 | 3.60 – 4.05 | Monoclinic | DR_B- |