摩氏硬度(du)(du)10，新摩氏硬度(du)(du)15，顯(xian)微硬度(du)(du)10000kg/mm2，顯(xian)微硬度(du)(du)比(bi)(bi)石(shi)(shi)英(ying)高1000倍，比(bi)(bi)剛玉(yu)高150倍。金剛石(shi)(shi)硬度(du)(du)具有(you)方向性，八面(mian)(mian)體(ti)晶(jing)面(mian)(mian)硬度(du)(du)大于(yu)菱形十(shi)二(er)面(mian)(mian)體(ti)晶(jing)面(mian)(mian)硬度(du)(du)，菱形十(shi)二(er)面(mian)(mian)體(ti)晶(jing)面(mian)(mian)硬度(du)(du)大于(yu)六面(mian)(mian)體(ti)晶(jing)面(mian)(mian)硬度(du)(du)。

依照摩氏硬(ying)度(du)(du)標(biao)準(Mohs hardness scale)共分10級(ji)(ji)，鉆石(金剛石)為(wei)(wei)最(zui)高級(ji)(ji)第10級(ji)(ji)；如(ru)小刀其硬(ying)度(du)(du)約為(wei)(wei)5.5、銅幣約為(wei)(wei)3.5至(zhi)4、指甲約為(wei)(wei)2至(zhi)3、玻璃(li)硬(ying)度(du)(du)為(wei)(wei)6。