Pretty much. Soft, Hard, True Hard, Translucent, and Black are all some odd %99 Novaculite, a form of silica if I remember right. The difference is the density of the stone. And when we get to the densest part of the spectrum they break it up by color somewhat. True Hard stones are mottled/banded or a hodge podge of color. Translucents are as the name suggests and as homogenous in coloration as they can manage. And Surgical black stones are, of course, black/dark grey.