Quartz
Amethyst
Amethyst is purple quartz, the most valued quartz colour. Its colour can sit in zones within a crystal, so cutters orient the stone to make it look even.
Amethyst
At a glance
- Mineral
- Quartz, purple from iron and natural irradiation
- Refractive index
- 1.55
- Dispersion (C–F)
- 0.008
- Specific gravity
- 2.65
- Mohs hardness
- 7
- Wear
- Fine for rings with some care; quartz scratches from everyday dust over the years.
Amethyst in Jart
The look in the studio's material library, with the values the renderer uses.
| Stone | Colour | RI | Dispersion C–F | Abbe | SG | Colour depth |
|---|---|---|---|---|---|---|
| Amethyst | #9a51ce | 1.55 | 0.008 | 69 | 2.65 | 5.2 mm |
RI refractive index (nd). Dispersion C–F nF − nC, the spread between blue and red light; many gem tables quote the B–G figure instead (diamond 0.044, here 0.025). Abbe number: lower means more fire. SG specific gravity, used for carat estimates in Design Facts. Colour depth the path through the stone after which white light takes the stone's full colour; shorter paths look paler.
How it renders
With a refractive index of 1.55, a polished amethyst facet reflects 4.7% of light that meets it face-on (diamond: 17.2%). Light inside the stone that meets a facet more than 40.2° from straight on cannot leave and is reflected back in; the smaller that angle, the more light a good cut returns to the eye (diamond 24.4°, quartz 40.4°).
Its dispersion (C–F) is 0.008, 32% of diamond's, which sets how much fire, the flashes of colour, a render shows under small, bright lights.
Quartz has a modest refractive index and low fire, so an amethyst renders with calmer sparkle than sapphire and relies on its colour.
- 1 mm
- 3 mm
- 6 mm
- 10 mm
Related stones
Render amethyst on your own design.
Open a 3DM, STL or GLB file, or a sample ring, choose the stone and the metal, and render it photoreal in your browser. No account needed.