Heart of the Ocean 

A large, fictional precious gem that some old lady dropped in the north Atlantic because she fell in love with some poor drifter who drew a caricature of her naked wearing only that stone, and shortly after drowned.

Brock: "Lizzy, do you know where the Heart of the Ocean is?"
Lizzy: "Um, I think my grandmother tossed it to Leonardo."

Heart of the Ocean by Clipperbox October 27, 2007