Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethystand 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.
The colour of the zones visible within ametrine are due to differing oxidation states of iron within the crystal. The different oxidation states occur due to there being 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 received the Anahi mine in Bolivia as a dowry.
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. Green-yellow or golden-blue ametrine does not exist naturally.
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