Diamond hardness: Mohs hardness 10, new Mohs hardness 15, microhardness 10000kg/mm2, microhardness is 1000 times higher than that in time and 150 times higher than that in corundum. The hardness of diamond is directional. The hardness of octahedral crystal face is greater than that of rhombohedral crystal face, and the hardness of rhombohedral crystal face is greater than that of hexahedral crystal face.
According to Mohs hardness scale, it is divided into 10 grade, with diamond as the highest grade and 10 grade. For example, the hardness of knives is about 5.5, copper coins are about 3.5 to 4, nails are about 2 to 3, and the hardness of glass is 6.
Extended data
Structural attributes of diamonds: diamond structure is divided into; Equiaxed tetrahedral cubic and hexagonal diamonds. In diamond crystal, carbon atoms are interconnected by tetrahedral bonds, forming an infinite three-dimensional skeleton, which is a typical atomic crystal. Each carbon atom forms a valence bond with the other four carbon atoms through SP3 hybrid orbitals, forming a regular tetrahedron.
Because the C-C bond in diamond is very strong, all valence electrons participate in the formation of valence bond, and there are no free electrons, so diamond is not only hard, but also has a very high melting point and is not conductive. In industry, diamonds are mainly used to make probes and abrasives for drilling, and also used to make high-grade decorations such as hand ornaments with complete shapes, which are very expensive.
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