Oh fun! Since I've uncharacteristically decided to make this a closed list, I suppose I should say a little more about the "made up rules in my head."
I had initially decided against bezoar because I couldn't imagine anyone wearing one as a sparkly jewel. But after looking at the meanings for jewel and gem, I think I'll add it.
While nephrite is pretty, the definitions I've seen make me think it's a cure rather than the problem. Now, of course, I'm wondering whether there's a list of old-timey medical cures, herbs, mithridates, and snake-oils around here (other than Chained_Bear's Aubrey/Maturin list, which I am avoiding for fear that once I start on that voyage, I won't come back).