Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined in Bolivia, although there are deposits being exploited in Brazil and India.

Artificial ametrine can be created by differential heat treatment of amethyst.

Most ametrine in the low price segment can surely be assumed to stem from synthetic material. Since 1994 a Russian laboratory has perfected the industrial production of bicolored quartz crystals that are later irradiated to bring out the typical ametrine colors.