What is sardonyx?
By Jared James · Last updated 21 May 2026
Definition
Sardonyx is a variety of onyx that shows alternating bands of sard, which is a reddish-brown to orange-brown form of chalcedony, and white or pale chalcedony. The contrasting layers made it highly prized in antiquity for carving cameos and intaglios because the craftsman could carve the design into one coloured layer while leaving the other as a contrasting background. Sardonyx has been used for rings, seals and brooches since ancient Greek and Roman times, and it remains a traditional choice for carved jewellery and signet-style pieces.
Frequently asked questions
- What is the difference between sardonyx and onyx?
- Onyx is the broader term for banded chalcedony, most commonly in black and white. Sardonyx is a specific variety where the bands alternate between reddish-brown sard and white chalcedony rather than black and white. Both are used in cameos and intaglios because of their contrasting layers.
- Is sardonyx used in cameos?
- Yes, sardonyx is one of the most traditional materials for carved cameos. The natural layering of the stone means a carver can work the design into the lighter layer to reveal it against the darker brown background, producing the classic relief portrait effect associated with fine antique cameos.
- Is sardonyx a precious stone?
- Sardonyx is classed as semi-precious. It is a chalcedony quartz variety, widely available and quite affordable, though fine antique carvings in sardonyx carry significant value because of the quality of the workmanship rather than the material itself.
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