Jewelry IdentifierBlack Gemstones
Black onyx is the most common black gemstone; black diamond, black spinel, and obsidian are other popular black stones.
'Black' gems are either truly black or so deeply colored they read as black. Some are minerals, some are volcanic glass or organic. Here's how to identify a black stone.
| Black gemstone | Hardness (Mohs) | What it is / how to spot it | Value |
|---|---|---|---|
| Black onyx | 6–7 | Solid opaque black chalcedony; most on the market is dyed agate. | Low |
| Black diamond | 10 | Opaque carbonado or heavily included diamond; hardest black gem. | Mid–High |
| Black spinel | 8 | Naturally jet-black, hard, and takes a bright polish. | Low–Mid |
| Obsidian | 5–5.5 | Volcanic glass — glossy black, sometimes with sheen or 'snowflake' patterns. | Low |
| Jet | 2.5–4 | Fossilized wood (lignite); very light and warm to the touch; Victorian mourning jewelry. | Low |
| Black tourmaline (schorl) | 7–7.5 | Opaque black tourmaline, often left rough or lightly polished. | Low |
| Hematite | 5–6 | Metallic gray-black iron oxide with a mirror shine; heavy for its size. | Low |
| Black star sapphire | 9 | Opaque black corundum showing a six-rayed star (asterism). | Mid |
| Black pearl | 2.5–4 | Organic Tahitian pearl in gray-to-black overtones. | Mid–High |
How to identify your black stone
Color alone won't confirm a gemstone — several black stones look alike but differ in hardness, weight, and value. The fastest way to know what you have is to photograph it and run it through the free Gemstone Identifier, then confirm whether it's natural or a simulant with the Is It Real? tool. For what the piece is worth, get a free jewelry appraisal.
Frequently asked questions
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