By Anais & Aimee · Updated 9 October 2026. Product examples use our current catalogue specifications; general material information is supported by the sources below.
Black onyx, black agate and obsidian can all create a dark, polished accent, but they are not interchangeable material names. Onyx and agate belong to the chalcedony family; obsidian is natural volcanic glass. For jewellery shopping, start with the written material specification, then compare the shape, setting and size.
Black onyx, agate and obsidian compared
| Material | What the name describes | A useful buyer question |
|---|---|---|
| Onyx | A variety of chalcedony associated with straight, parallel bands; black onyx is also used as a trade description for black jewellery material. | Is the colour treated, and what material is specified for this piece? |
| Agate | Chalcedony commonly characterised by bands; jewellery sold as black agate may have been colour treated. | Are treatments disclosed, and what do the actual beads or stones look like? |
| Obsidian | Natural glass formed through volcanic activity. | Is the material identified as obsidian, rather than using it as a general name for a black stone? |
These descriptions explain material categories, not a home identification method. Colour alone cannot establish which material you have, and a photograph cannot confirm treatment. Gem-A explains both chalcedony varieties and dyed gemstones. Where a listing does not disclose treatment, ask before purchasing rather than assuming “untreated”.
Choose a design as well as a stone
A defined pendant: the Cove Black Onyx Pendant Necklace is currently specified in our catalogue as black onyx with a silver shell detail. Its chain is listed at 40 cm plus a 6 cm extension. It is an option to compare if you want one central focal point.
A beaded contrast: the Albany Pearl & Black Agate Necklace combines pearls and black agate beads. Its current specification is black agate, and the listed necklace length is 38 cm plus a 6 cm extension. Compare that length against a necklace you already wear.
A silver drop earring: the Scarab Black Obsidian Silver Drop Earrings use black obsidian according to our catalogue, with oxidised sterling silver detailing and a listed drop of 2.5 cm. The setting creates a different silhouette from a necklace or a row of beads.
What to check on the product page
- The exact stone name: a collection can contain several black materials, including non-stone alternatives, so read each product specification.
- Metal and finish: silver-coloured and gold-coloured are appearances. Check the stated base metal and surface finish separately.
- Measurements: check bead diameter, pendant size, earring drop or chain length as appropriate.
- Treatment information: ask for clarification if colour treatment matters to your purchase. A treatment and an imitation are different issues.
Can you identify a black stone at home?
Not reliably from colour or a simple online checklist. Do not scratch, heat or apply solvents to your jewellery to test it. If the identity is important, ask the seller for supporting information or consult a qualified gemmologist. Product names and photographs are not laboratory reports.
For day-to-day care, follow the instructions for the complete piece, including its metal, finish and any pearl or shell components. Avoid treating a mixed-material necklace as though every part can be cleaned in the same way.
Explore our black stone jewellery collection or use the necklace length guide to compare fit.
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