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Spinel

JewelryWiki Editorial·3 sources·Reviewed 2026-07-31
Spinel specimen
Spinel specimen. Robert M. Lavinsky, CC BY-SA 3.0 · Wikimedia Commons

Singly refractive and hardness 8 — historically mistaken for ruby, including in several crown jewels.

Properties

PropertyValueAuthority
Mohs hardness8 [1]—
Refractive index1.712–1.762 [1]—
Specific gravity3.54–3.63 [1]—
Crystal systemCubic [3]—
Birthstone monthAugust — added as an official August birthstone in 2016 by Jewelers of America and AGTA, alongside peridot. [2]—

Sources

  1. International Gem Society — reference charts (Mohs hardness, specific gravity, refractive index) — International Gem Society (IGS reference charts)
  2. Jewelers of America — Birthstones — Jewelers of America (Jewelers of America, Birthstones)
  3. Wikipedia — mineral article infoboxes (crystal system) — Wikipedia contributors (Wikipedia mineral infoboxes)