**grins**
Okay, it's not the exact names, but I'll give you two of those, delilah!
The ring with the ost venom is one ... it's called a "fang ring" and is described in Explorers of Gor. The name comes from the fact that it is worn like a normal ring, but there is a place to press which causes a "fang" to raise up. The venom or poison is stored inside the ring, the fang is just like a snake's fang, hollow and when it punctures the skin, the poison is delivered through it.
The ring slaves would know well is the other one I'll give you because the description is pretty close, but I won't give you the full name just yet. It's known by the name of the person who designed it .. and this is a ring (or set of rings) often used in a slave coffle, generally around the ankles rather than connecting collars like some coffles used. If you can figure out who this ring is named for, you can tell what City he's from as well.
Okay, I said I'd give a couple more hints too, so here they are ... both of these remaining rings ARE jewelry. The one which wasn't "really" jewelry would have been the one the slaves would know.
The ring of red metal would have been unique, only one made as far as I'm aware, and I only remember it having been mentioned in one book. It had no real purpose other than recognition of the wearer's family.
The ring that gave an unusual ability was one of a set, originally five of these rings were created but we only see one of them being used within the books, although it is used more than once and is used by a few different people. We know that two of the rings were destroyed and the final two, we don't really know what happened to them.