posed
of brickdust and resin, he applies the edge of a steel knife to the
scratched surface, and strikes a quick, hard blow with a slender rod.
If he has struck the lines of cleavage, the external scale is at once
removed, for the diamond, despite its hardness, is quite easily
fractured. Then the split surface must be polished. If no other scale
or marked inequality needs removing by splitting, the next operation is
that of grinding.
Cutting
As the diamond is the hardest of all known substances, it is evident that much patience and strength are required in reducing
