Thanks, Will. Those are beautiful. I don't know what the stone is - hematite is a guess because it's black, has a soft sheen, and no inclusions I can see. I'll see if I can get hold of some clay to make an impression. I can see two standing figures and a seated one, and a star design that's so worn as to almost be gone. The technique looks similar to museum examples I've seen, but of course that doesn't tell you much.