Gemstone Hardness
All gemstones have different hardness measured by Mohs’ scale.
The scale was developed by German gem expert, Friedrich Mohs in 1812. The scale measures gemstones from 1 to 10.
1 is the most easily scratched while 10 is the most scratch resistant.
Knowing a gemstone's hardness can help when making jewellery designs.
Prevent scratching of gemstones in a design by using gemstones of similar hardness next to each other.
|
Scale of Hardness |
Resilience |
Stones |
|
0-1 |
Can scratch with your fingernail |
Talc |
|
1-1½ |
Can scratch with your fingernail |
Gypsum
Sulphur |
|
2-3 |
|
Amber |
|
2-4 |
|
Ivory |
|
3-4 |
Can scratch with a coin |
Pearl
Coral |
|
3½-4 |
|
Malachite |
|
4 |
Can scratch with a knife |
Rhodochrosite |
|
4½ |
Can scratch with a copper coin. |
Calcite
Kyanite
(lengthwise to grain) |
|
5-6 |
This gemstone scratches softer glass. |
Fluorite
Lapis Lazuli
Turquoise |
|
5½-6½ |
|
Opal |
|
6-6½ |
Can scratch with a steel file |
Kyanite (across wise to grain)
Moonstone |
|
6½-7 |
Can scratch with dust. Most dust is silicate (which is a
7) clean all your gemstones below 7 with a dust free cloth. |
Quartz
Tanzanite
Apatite
Peridot |
|
7 |
Can scratch with glass and will scratch all other gemstones of lower scale |
Citrine
Amethyst |
|
7-7½ |
|
Tourmaline
Garnet |
|
7½-8 |
|
Emerald |
|
8 |
This gemstone will scratch lower value gemstones and quartz. |
Topaz |
|
8½ |
|
Alexandrite |
|
9 |
This gemstone will scratch previous stones |
Ruby
Sapphire |
|
10 |
This gemstone will scratch previous stones. Saws and drill-bits are often diamond-tipped. It will cut through most things. |
Diamond |