The MOHS Scale Systems
The MOHS scale system was developed by Friedrich Mohs, a German gem expert, in 1812. The Mohs scale is still in use today to determine the hardness of most gemstones.
The Mohs scale involves a numerical value- 1 through 10, with 1 being the most easily scratched, and 10 being the most scratch-resistant.
Gem/Mineral |
Hardness |
Birthstone |
*Amber |
2.5 |
|
*Ivory |
2.5 |
|
*Jet |
2.5 |
|
*Mabe Shell |
2.5 |
|
Serpentine |
2.5-5.0 |
|
*Tortoise Shell |
2.5 |
|
Calcite |
3.0 |
|
* Pearl |
3.0 |
June |
Azurite |
3.5 |
|
*Coral |
3.5 |
|
Fluorite |
4.0 |
|
Malachite |
4.0 |
|
Rhodocrosite |
4.0 |
|
Apatite |
5.0 |
|
Dioptase |
5.0 |
|
Moldavite |
5.0 |
|
Obsidian |
5.0 |
|
Titanite |
5.0 |
|
Diopside |
5.5 |
|
Lapis |
5.5 |
December |
Milarite |
5.5 |
|
Sodalite |
5.5 |
|
Black Opal |
6.0 |
October |
Labradorite |
6.0 |
|
Moonstone |
6.0 |
June |
Opal |
6.0 |
October |
Orthoclase |
6.0 |
|
Rhodonite |
6.0 |
|
Scapolite |
6.0 |
|
Spectrolite |
6.0 |
|
Sunstone |
6.0 |
|
Turquoise |
6.0 |
December |
Andradite |
6.5 |
|
Demantoid |
6.5 |
January |
Fire opal |
6.5 |
October |
Hematite |
6.5 |
|
Nephrite Jade |
6.5 |
|
Peridot |
6.5 |
August |
Tanzanite |
6.5 |
December |
Kyanite |
7.0-5.0 |
|
Agate |
7.0 |
|
Amethyst |
7.0 |
February |
Ametrine |
7.0 |
|
Aventurine |
7.0 |
|
Bloodstone |
7.0 |
March |
Blue Chalcedony |
7.0 |
|
Carnelian |
7.0 |
|
Cat's Eye Quartz |
7.0 |
|
Chrysoprase |
7.0 |
|
|
Gem/Mineral |
Hardness |
Birthstone |
Citrine |
7.0 |
November |
Goldenite |
7.0 |
|
Grossular Garnet |
7.0 |
January |
Hiddenite |
7.0 |
|
Iolite |
7.0 |
|
Jadeite Jade |
7.0 |
|
Jasper |
7.0 |
|
Kunzite |
7.0 |
|
Mandarin Garnet |
7.0 |
January |
Onyx |
7.0 |
|
Petrified Wood |
7.0 |
|
Quartz Crystal |
7.0 |
April |
Rhodolite |
7.0 |
January |
Rose Quartz |
7.0 |
|
Sard |
7.0 |
|
Sardonyx |
7.0 |
August |
Smokey Quartz |
7.0 |
|
Spessartine |
7.0 |
|
Tiger's Eye Quartz |
7.0 |
|
Tsavorite |
7.0 |
January |
Hessonite |
7.25 |
January |
Pyrope |
7.25 |
January |
Almandine Garnet |
7.5 |
January |
Andalusite |
7.5 |
|
Aquamarine |
7.5 |
March |
Danburite |
7.5 |
|
Emerald |
7.5 |
May |
Goshenite |
7.5 |
|
Heliodor |
7.5 |
|
Hyacinth |
7.5 |
|
Indicolite |
7.5 |
|
Morganite |
7.5 |
|
Red Beryl |
7.5 |
|
Rubellite |
7.5 |
|
Sillimanite |
7.5 |
|
Tourmaline |
7.5 |
October |
Uvarovite Garnet |
7.5 |
January |
Zircon |
7.5 |
December |
Blue Topaz |
8.0 |
December |
Spinel |
8.0 |
|
Topaz |
8.0 |
November |
Alexandrite |
8.5 |
June |
Cat's Eye Chrysoberyl |
8.5 |
|
Blue Sapphire |
9.0 |
September |
Padparadscha |
9.0 |
September |
Ruby |
9.0 |
July |
Sapphire |
9.0 |
September |
Diamond |
10.0 |
April |
|
Any gemstone listed above can be scratched by a gemstone with the same hardness,
or any harder gemstone farther down the list that is greater than the gem to be tested.
*not technically a gem or mineral, but organic matter
