On the widely used MOHS scale of hardness, diamonds are at a 10 scale, and crystal is at a 7 scale.
(diamonds; are; at a 10 scale; L:On the widely used MOHS scale of hardness) (crystal; is; at a 7 scale)
diamonds crystal
are is
at a 10 scale L:On the widely used MOHS scale of hardness
at a 7 scale