The Mohs scale of gemstone / mineral hardness was created by the German mineralogist Friedrich Mohs in 1822 to measure the relative hardness of various gemstone minerals. He based it on ten minerals that were available to him at the time. Moh’s is an ordinal scale and you have to ...
This is evidence of the hardness of sapphire and a testament to its place at number 9 on the Mohs hardness scale. More germane to this discussion of gemstone hardness though, is the reason why sapphire and ruby (of the same family, Corundum) are so highly recommended for everyday wear je...