A few years ago I decided to collect Chinese "chops" or stone seals.
That collection didn't go very far. I think I've got 4.
This chop is a ring to be worn on your finger.

Maybe you've seen on Oriental paintings, the small red signature
in the lower corner or to the side? It's done with a hand carved stone like these,
dipped in sumie ink or watercolor.
Also, I think they were used for signatures on documents.