Mohs Hardness Scale

The Mohs Hardness Scale, including layman's examples of hardness, is a jewelry-industry guide for over a dozen different gemstones.

Last edited: 5/21/2021
Mohs Hardness Scale
1. Can be scratched easily with a fingernail Sulphur: 1–1-1/2
2. Can be scratched with a fingernail Amber: 2–3
Ivory: 2–4
3. Can be scratched with a coin Pearl: 3–4
Coral: 3–4
Malachite: 3-1/2 –4
4. Can be scratched easily with a knife;
cannot scratch glass		 Rhodochrosite: 4
5. Can be scratched with a knife; can just
scratch glass		 Lapis lazuli: 5–6
Turquoise: 5–6
Opal: 5-1/2 –6-1/2
6. Can be scratched with a steel file; easily
scratches window/bottle glass		 Moonstone: 6–6-1/2
Tanzanite: 6-1/2 –7
Peridot: 6-1/2 –7
Zircon: 6-1/2 –7-1/2
7. Easily scratches metal, glass and softer stones Citrine: 7
Amethyst: 7
Tourmaline: 7–7-1/2
Garnet: 7–7-1/2
Emerald: 7-1/2 –8
8. Scratches quartz and softer stones Topaz: 8
Alexandrite: 8-1/2
9. Scratches topaz and softer stones Ruby: 9
Sapphire: 9
10. Scratches ruby Diamond: 10