What is the hardness of diamond on the Mohs scale?
5
7
9
10
Diamond is the hardest naturally occurring substance on Earth, with a hardness of 10 on the Mohs scale. This means that it is very difficult to scratch or damage a diamond.
The 10-point scale of mineral hardness. One the Mohs scale of relative hardness, a diamond is rated as 10. This means that it is the hardest mineral known to man. Only a mineral that is the same hardness grade can scratch the mineral. Sapphires for example are graded 9 on the Mohs scale which means that only another Sapphire or a diamond (because the diamond is harder) can scratch a Sapphire. Yet, Sapphires cannot scratch a diamond because it is softer.