For this you would require two specimens of the same nature. You take a normal hammer and a paper and pencil, and hit it gently and continue to hit it harder till it breaks, record the results.
The scratch test is used by scientists and people who study rocks and minerals to determine the strength of the rock. They have the scratchers numbered one through ten and scratch the rock or mineral until the scratcher makes a mark in the mineral then they know the strength of the rock.
