Hardness

 

The resistance of a substance to being scratched. Diamond is 10 on the Mohs scale of hardness. Tests prove that diamond is approximately 10 to 150 times as hard as corundum, the next hardest mineral. The variation stems not only from differences obtained by different hardness-testing methods, but also from the fact that various directions on a given diamond's surface show a considerable variation in resistance to abrasion.