| Violet or Purple Gemstones |
|---|
| Gemstone | Crystal System | Density | Hardness | Refractive index | Treatments |
 Amethyst |
hexagonal | 2.66 | 7 | 1.544-1.553 | heating alters to citrine |
 Corundum |
trigonal | 4.00 | 9.0 | 1.762-1.770 | none |
 Diamond |
cubic | 3.52 | 10 | 2.417 | radiation, drilling, fracture filling |
 Garnet |
cubic | 3.40 | 5.5-6.5 | 1.700-1.746 | none |
 Jadeite |
microcystalline | 3.34 | 6.5-7.0 | 1.660-1.680 | dying |
 Kunzite |
monoclinic | 3.18 | 6.0-7.0 | 1.660-1.676 | light will fade |
 Quartz |
hexagonal | 2.66 | 7.0 | 1.544-1.553 | fracture filling |
 Sapphire |
hexagonal | 4.00 | 9 | 1.762-1.770 | heat, fracture filling |
 Spinel |
cubic | 3.60 | 8 | 1.714-1.750 | none |
 Tanzanite |
orthorhombic | 3.30 | 6.0-7.0 | 1.690-1.700 | heat |
 Tourmaline |
trigonal | 3.06 | 7.0-7.5 | 1.630-1.662 | Heat, radiation |