Gemstones
Hardness and toughness are different properties, and confusing them is the commonest mistake in buying advice. Mohs measures scratch resistance only; toughness measures resistance to chipping and breaking. Both are shown separately below, because a hardness-10 stone can still chip and a 7.5 stone can still be a poor daily ring.
28 entries
All cited
SortedA–Z
| Name | Mohs hardness | Toughness | Stability | Refractive index | Specific gravity | Crystal system | Suitability for daily wear |
|---|---|---|---|---|---|---|---|
| Alexandrite | 8½ | — | — | — | — | Orthorhombic | — |
 Amber | — | — | — | 1.539–1.545 | 1.05–1.09 | — | — |
 Amethyst | 7 | — | — | — | — | Trigonal | — |
 Apatite | — | — | — | 1.628–1.649 | 3.16–3.23 | Hexagonal | — |
 Aquamarine | 7½–8 | — | — | — | 2.68–2.74 | Hexagonal | — |
 Chrysoberyl | — | — | — | 1.746–1.763 | — | Orthorhombic | — |
 Citrine | 7 | — | — | — | — | Trigonal | — |
 Coral | — | — | — | 1.486–1.658 | 2.60–2.70 | — | — |
 Diamond | 10 — the hardest gemstone | Not the toughest despite being the hardest. GIA: while they resist scratching … | — | 2.417–2.419 | 3.50–3.53 | Cubic | Excellent for daily wear on the hardness axis. Chipping remains possible at th… |
 Emerald | 7.5 to 8 | Fair to good — requires more care in wear than ruby or sapphire, and can chip … | — | — | 2.67–2.78 | Hexagonal | Wearable daily only with care and a protective setting. The limiting factor is… |
 Fluorite | — | — | — | 1.434 | 3.00–3.25 | Cubic | — |
 Garnet | 6½–7½ | — | — | — | — | Cubic | — |
 Jadeite | 6½–7 | — | — | 1.652–1.688 | 3.30–3.38 | Monoclinic | — |
 Kunzite | 6½–7 | — | — | 1.660–1.681 | — | Monoclinic | — |
 Malachite | — | — | — | 1.655–1.909 | 3.25–4.10 | Monoclinic | — |
 Moonstone | — | — | — | 1.518–1.526 | 2.56–2.59 | Monoclinic | — |
 Nephrite | 6–6½ | — | — | 1.600–1.627 | 2.90–3.03 | Monoclinic | — |
 Opal | 5½–6½ | Low. GIA groups opal with tanzanite as "not-so-tough" gems that should be prot… | — | 1.370–1.520 | — | Amorphous | Not recommended for daily rings or bracelets. GIA advises earrings or necklace… |
 Pearl | — | — | Low. GIA: long-term exposure to heat and light can damage most organic gems in… | — | 2.60–2.85 | — | Wearable regularly with care, but should be put on after perfume and cosmetics… |
 Peridot | 6½–7 | — | — | 1.650–1.703 | 3.28–4.39 | Orthorhombic | — |
 Ruby | 9 | Excellent. | — | — | 3.97–4.05 | Trigonal | Excellent. High on both axes that matter, which is why corundum is the standar… |
 Sapphire | 9 | Excellent. | — | — | 3.95–4.03 | Trigonal | Excellent. The most durable common alternative to diamond for an engagement ri… |
 Spinel | 8 | — | — | 1.712–1.762 | 3.54–3.63 | Cubic | — |
 Tanzanite | 6½–7 | Low. GIA groups tanzanite with opal as "not-so-tough" gems needing protection … | Poor under prolonged light. GIA lists tanzanite with kunzite and topaz as gems… | 1.691–1.700 | 3.35 | Orthorhombic | Occasional wear. Earrings and necklaces preferred; reserve rings and bracelets… |
 Topaz | 8 | — | Can fade or change colour from prolonged exposure to light — GIA lists topaz a… | 1.609–1.643 | 3.49–3.57 | Orthorhombic | — |
 Tourmaline | — | — | — | 1.614–1.666 | 2.82–3.90 | Hexagonal | — |
 Turquoise | — | — | — | 1.610–1.650 | 2.31–2.84 | Triclinic | — |
 Zircon | 6½–7½ | — | — | 1.810–2.024 | 3.93–4.73 | Tetragonal | — |
Showing all 28Every figure traces to a named source with a pinpoint locator. Values we could not source are left blank rather than estimated.