According to rub standard of family name hardness (Mohs Hardness Scale) divides 10 level in all, diamond (diamond) for the superlative degree the 10th class; If its hardness is the penknife about 5.5, schilling is about 3.5 to 4, fingernail is about 2 to 3, vitreous hardness is 6.
Grade 1 steatitic
Grade 2 gesso
Grade 3 calcite
Grade 4 fluorite
Grade 5 apatite
Grade 6 orthoclase
Grade 7 quartz
Grade 8 topaz
Grade 9 steel jade
Grade 10 diamond