Ametrine is a combination of amethyst and citrine. The most valuable kind of ametrine is half fine amethyst, half fine citrine with a clear boundary between the two. Usually, ametrine over 5 carats shows the best color and separation. There is only one source in the world for natural ametrine, which is in Bolivia. Treated ametrine is also available. Amethyst can be partially heated or irradiated or a combination of both in order to produce ametrine. Due to its availability, ametrine is also used frequently for unique “fantasy cuts” or is carved into sculptures.