Zircon
JewelryWiki Editorial·3 sources·Reviewed 2026-07-31
The highest refractive index of any common natural gem except diamond. Not to be confused with cubic zirconia, which is a synthetic and a different material entirely.
Properties
| Property | Value | Authority |
|---|---|---|
| Mohs hardness | 6½–7½ [1] | — |
| Refractive index | 1.810–2.024 [1] | — |
| Specific gravity | 3.93–4.73 [1] | — |
| Crystal system | Tetragonal [3] | — |
| Birthstone month | December — blue zircon is one of three official December stones, with turquoise and tanzanite. [2] | — |
Sources
- 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)