Chalcedony

Onyx

Black onyx is chalcedony, nearly always dyed to an even black. It is used for signet ring tablets, inlays and cufflinks.

  • OnyxOnyx

At a glance

Mineral
Chalcedony (fine-grained quartz); usually dyed black
Refractive index
1.544
Dispersion (C–F)
0.008
Specific gravity
2.65
Mohs hardness
6.5–7
Wear
Durable for rings and inlays.

Onyx in Jart

The look in the studio's material library, with the values the renderer uses.

Optics of Onyx in Jart
StoneColourRIDispersion C–FAbbeSGColour depth
Onyx#1414161.5440.008692.650.26 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 1.544, a polished onyx facet reflects 4.6% of light that meets it face-on (diamond: 17.2%). Light inside the stone that meets a facet more than 40.4° 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.

It absorbs light within a fraction of a millimetre, so in a render it shows only its surface: its look comes from the polish and the reflections of the lighting. A light with clear highlights gives it its gloss.

  • 1 mm
  • 3 mm
  • 6 mm
  • 10 mm
Onyx: the colour of white light after 1, 3, 6 and 10 mm of stone. It takes the full preset colour at 0.26 mm.

All gemstones · Metals · Stone and metal pairings · Finishes

Render onyx 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.

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