The Mohs scale determines the hardness of gemstones by assessing if one can scratch another; the harder stone leaves a mark on the softer one. Unlike a linear progression, the hardness scale is akin to stepping stones, with varying distances between them rather than a consistent increase.
| Gemstones | Hardness Level | Gemstones | Hardness Level |
|---|---|---|---|
| Agate | 7.0 | Jet | 2.5 |
| Alexandrite | 8.5 | Kunzite | 7.0 |
| Amber | 2.5 | Kyanite | 7.0 / 5.0 |
| Amethyst | 7.0 | Labradorite | 6.0 |
| Ametrine | 7.0 | Lapis Lazuli | 5.5 |
| Andalusite | 7.5 | Malachite | 4.0 |
| Apatite | 5.0 | Moonstone | 6.0 |
| Aquamarine | 7.5 | Morganite | 7.5 |
| Aventurine | 7.0 | Obsidian | 5.0 |
| Azurite | 3.5 | Onyx | 7.0 |
| Beryl | 7.5 | Opal | 6.0 – 6.5 |
| Bloodstone | 7.0 | Pearl | 3.0 |
| Blue Chalcedony | 7.0 | Peridot | 6.5 |
| Carnelian | 7.0 | Rhodochrosite | 4.0 |
| Cat’s Eye – Chrysoberyl | 8.5 | Rhodonite | 6.0 |
| Cat’s Eye – Quartz | 7.0 | Ruby | 9.0 |
| Chrysoprase | 7.0 | Sapphire | 9.0 |
| Citrine | 7.0 | Sardonyx | 7.0 |
| Coral | 3.5 | Scapolite | 6.0 |
| Diamond | 10.0 | Serpentine | 2.5 – 5.0 |
| Emerald | 7.5 | Sillimanite | 7.5 |
| Fluorite | 4.0 | Quartz | 7.0 |
| Garnet | 6.5 – 7.0 | Sodalite | 5.5 |
| Goldenite | 7.0 | Spectrolite | 6.0 |
| Goshenite | 7.5 | Spinel | 8.0 |
| Heliodor | 7.5 | Sunstone | 6.0 |
| Hematite | 6.5 | Tanzanite | 6.5 |
| Hiddenite | 7.0 | Tiger’s Eye | 7.0 |
| Howlite | 3.5 | Topaz | 8.0 |
| Iolite | 7.0 | Tortoiseshell | 2.5 |
| Ivory | 2.5 | Tourmaline | 7.5 |
| Jade | 6.5 – 7.0 | Turquoise (stabilized) | 6.0 |
| Jasper | 7.0 | Zircon | 7.5 |
