Obsidian vs Jet
Obsidian and Jet are easy to confuse. Here’s how they stack up on the properties that actually separate them.
| Obsidian | Jet | |
|---|---|---|
| Colour | Black | Black |
| Mohs hardness | 5–6 | 2.5–4.0 |
| Lustre | Vitreous | — |
| Streak | — | Brown |
| Cleavage | — | None |
| Fracture | Conchoidal | Conchoidal |
| Chemical formula | — | Variable, but rich in carbon |
| Specific gravity | c. 2.4 | 1.3–1.4 |
| Typical value | $5–$9 a polished piece | — |
Value = estimate only (gems priced per carat from price guides; common stones from recent eBay sold listings). See each stone's page and our methodology.
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Frequently asked questions
What's the easiest way to tell Obsidian from Jet?
Hardness is the quickest test: Obsidian is Mohs 5–6 and Jet is Mohs 2.5–4.0.