Amethyst / Ametrine - Great polished double endings from Bolivia.

Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mix of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrienes are mined in Bolivia, but there are deposits in Brazil and India being exploited. The color of the zones visible in ametrien are due to the different oxidation states of iron in the crystal. The various oxidation states occur as a result that a temperature gradient over the crystal during its formation Artificial ametrine can be created by differential heat treatment of amethyst. Legend has it that ametrien was first introduced to Europe by gifting a conquistador to the Spanish queen, after having a mine in Bolivia as a dowry when he married a princess from the native Ayoreos tribe. Most ametrien in the low price segment can be assumed to originate from synthetic material. Since 1994 a Russian laboratory has perfected industrial production of bi-colored quartz crystals that were later irradiated to bring out the typical ametrine colors. Green - yellow or gold - blue ametrine does not occur naturally.