In this test a Diamond Indenter is pressed into the surface of the material being tested. Standard loads used include 5, 10, 20, 30, 50, and 100 kgf. (49,05, 98,1 196,2 490,5 and 981 N).The load is stated in specifying the hardness number i.e HD(10) = 100. the indenter is a square based pyramid (136
o included angle )to suit the material being testedThe Hardness Number HD = 1.844 x Load/ Average diagonal length of indentation