Diamond
DiamondJewelryWiki Editorial·4 sources·Reviewed 2026-07-31
The hardest gemstone, and routinely assumed to be indestructible. GIA is explicit that it is not: diamonds resist scratching, but a hard blow can cleave or fracture one.
Properties
| Property | Value | Authority |
|---|---|---|
| Mohs hardness | 10 — the hardest gemstone [1] | — |
| Toughness | Not the toughest despite being the hardest. GIA: while they resist scratching and abrasions, diamonds can be cleaved or fractured by a hard blow. [1] The single clearest demonstration that hardness and toughness are different properties. | — |
| Refractive index | 2.417–2.419 [2] | — |
| Specific gravity | 3.50–3.53 [2] | — |
| Crystal system | Cubic [4] | — |
| Suitability for daily wear | Excellent for daily wear on the hardness axis. Chipping remains possible at the girdle from a hard knock, which a protective setting mitigates. [1] | — |
| Birthstone month | April [3] | — |
Sources
- GIA — More than the Mohs Scale: Understanding Gem Durability — Gemological Institute of America (GIA 4Cs, "More than the Mohs Scale" (14 March 2016))
- International Gem Society — reference charts (Mohs hardness, specific gravity, refractive index) — International Gem Society (IGS reference charts)
- Jewelers of America — Birthstones — Jewelers of America (Jewelers of America, Birthstones)
- Wikipedia — mineral article infoboxes (crystal system) — Wikipedia contributors (Wikipedia mineral infoboxes)