Description
Ametrine, also known as trystine or by its trade name 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, but deposits in Brazil and India are exploited. The color of the zones visible in ametrine are due to the different oxidation states of iron within the crystal. These different oxidation states occur due to a temperature gradient across the crystal during its formation. Artificial ametrine can be created by differential heat treatment of amethyst. Legend has it that ametrine was first introduced to Europe by a conquistador's gifts to the Spanish queen after he had a mine in Bolivia as a dowry when he married a princess from the indigenous Ayoreos tribe. Most ametrine in the low-priced range can be assumed to originate from synthetic material. Since 1994, a Russian laboratory has perfected the industrial production of two-tone quartz crystals, which are then irradiated to produce the characteristic ametrine colors. Green-yellow or gold-blue ametrine does not occur naturally.
