Please refer to my post from a short time ago, called "Re. Re. Zi Imitation"—where I discuss doing a hardness test.

In the 1970s, the number of Chinese serpentine beads being offered as "jade" was staggering.

Jamey

P.S. The intent of using a hot-needle is not "penetration." It is to apply heat. In testing beads it is easy to insert the point of a heated steel needle into the perforation aperture—whereupon you stroke it against the wall of the perforation. But in any other circumstance, you need not "stab" the item. Use the side of the point, and stroke it across the surface (as carefully as possible).