Just bought a nice necklace with beads by The Dot Artist, featuring some sort of jade simulant.

Susan Dods' collection has some carved beads from this stone, which she describes as serpentine. However, somewhere in the back of my mind is the Chinese description as "mountain jade" and that it's a type of marble. My gemo equipment is packed away, so no refractometer handy to help clear up the ID, thus I'm going with Susan. But if anyone knows anything different, let's hear it.

Photographed against a slab of actual jadeite rough from Burma.

The clasp is stamped "Silver." Circa 1970s, more or less? Notice how they've been carefully graduated, unlike more uniformly produced beads from the 1990s.