Where's Marie Curie When You Need Her?

After the extremely rare occasion when Leroy buys Loretta a ring, what does she do but bring it right to the jewelers to get it appraised! You can't blame her for her curiosity, as Leroy's cheapness is legendary. Who knows where he got that thing? Why, its stone consists of a mineral unknown to science! Or, it could be the jeweler flunked chemistry in high school.