I just purchased a great white shark's tooth. The seller informs me that it was taken from a shark that died in the 1970's. I had my jeweler make a beautiful pendant, using 18kt gold cap on the root with a small image of a shark on the front. My problem is I wore it for a few days and the white sharks tooth started to discolor from the oils from my skin. Now it is starting to turn brown. Does anyone know of a way to whiten the tooth again? I placed the tooth in bleach for 3 days and no result. I was thinking of boiling the tooth in water and bleach. Can anyone give me suggestions on cleaning and preserving my specimen? Thanks....