The Jewel of Judgement was once the eye of the Serpent. The Serpent only has one eye at large; all Jewels are linked. (It’s all Mathematics, as Dworkin would say.)

The Jewel is apparently the repository for Amberite souls; everyone else’s souls go into the support for the promontory. In some places that means those souls enter scales of the local Wyrm, in others they become food for the local Kraken. There is some speculation that the entire eye-stealing incident may have been motivated by getting a better view after the universe ends. The Jewel, fortunately or unfortunately, acts as a sort of “soul velcro”, making it simple for the Court Necromancer of Amber to yank souls out of it and return Amberites to life.

Although there is only one Jewel, there are several Amberites who have it.

1. Neville, aka King Eric II had the Jewel as given to him by Jean, formerly on the mantel at House Swayvill. It is presumed that that instance is no more, after the Pattern Redraw Incident.
2. King Deirdre has one around her neck, as she is off to deal with a possible Gwen contingency/resurrection plan.
3. Hamster Dworkin has a Hamster-scale Jewel, which has briefly been in Norton’s eye, completely saning him for the nonce. It is said that that is forbidden from happening again.
4. Bucephalus, Malachai’s horse, has a Jewel, on his chest harness.
5. Both Janus and Corwin have been known to walk around with (the same set of) half a dozen Jewels. (Where is this set now? No one seems to know.)

Despite rumors otherwise, there is no Frog of Judgement, no matter what the lineage of the BobaFrogs, and the Frogdalorean armor might claim.