You can boil it, but make sure that it is a gradual increase in temperature. Don't drop the glass from room temperature into a 100 degree bot of boiling water, it may crack. Also, do not let it touch the metal parts of the pot or it will weaken.

Put your piece, 2 tablespoons of salt, and some alcohol in a ziploc bag and shake the bunch. The alcohol will turn brown. Rinse and repeat