Moh's Hardness Scale
When looking for gemstones for jewellery, engagement rings or othewise, you may see or hear your jeweller or your jewellers website mention Moh’s Hardness Scale.
What is the Moh’s Hardness Scale?
The Moh’s Hardness Scale is a relative system based on 10 different minerals and gemstones used as a reference for how easily specific gemstones scratch. 1 is the easiest to scratch and a 10 is the most difficult. Diamonds are a 10.
The concept is if you have a stone of unknown hardness, and reference mineral #5 can scratch it, then the hardness of your gem is less than or equal to a Mohs hardness of 5. Similarly, if your gem cannot be scratched by reference mineral #5, then its hardness is greater than or equal to a Mohs hardness of 5.
What Hardness is Preferred for Everyday Wear?
Moh’s Scale is the most commonly used system to rate the hardness of gemstones. Anything with a rating of or above 7 is what is most commonly used in jewellery today.
Diamonds are the hardest minerals on earth; they are 4-5 times harder than corundum, the family of sapphires and rubies, which are rated a 9 on the scale. Understandably, this is why diamonds are so desirable for engagement rings.
Moh's Hardness Scale
| Hardness | Mineral | Comparison |
| 10 | Diamond | |
| 9 | Corundum (Sapphire & Ruby) | |
| 8 | Topaz, Emerald, Aquamarine | Masonry drill bit (8.5) |
| 7 | Quartz (Amethyst, Citrine and Agate) | |
| 6 | Orthoclase | Nail (6.5) |
| 5 | Apatite | Knife (5.5) |
| 4 | Flurospar | |
| 3 | Calcite | Copper coin (3.5) |
| 2 | Gypsum | Fingernail (2.5) |
| 1 | Talc |
