Chalcedony
Red jasper
Jasper is an opaque, fine-grained quartz; iron oxides colour red jasper brick to blood red. It is cut as cabochons and beads.
Red jasper
At a glance
- Mineral
- Fine-grained quartz coloured by iron oxides
- Refractive index
- 1.54
- Dispersion (C–F)
- —
- Specific gravity
- 2.65
- Mohs hardness
- 6.5–7
- Wear
- Durable for most jewellery.
Red jasper 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 |
|---|---|---|---|---|---|---|
| Red jasper | #9c2f24 | 1.54 | — | — | 2.65 | opaque |
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 1.54, a polished red jasper facet reflects 4.5% of light that meets it face-on (diamond: 17.2%). Light inside the stone that meets a facet more than 40.5° 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°).
It is opaque: light reflects from its surface and does not travel through it, so it shows no fire, and its look comes from its colour, its polish and what the lighting reflects.
Like the other opaque stones it is a polished surface in a render: its look is set by its colour, the polish, and what the lighting reflects.
Related stones
All gemstones · Metals · Stone and metal pairings · Finishes
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