Ametrine

History
First recognized in 1977, and commercially available since 1980, ametrine is actually a combination of amethyst and citrine.

Features
Ametrine shows both the golden color of citrine and the violet of amethyst. Cut gemstones can show this dual coloring as either a straight line running through the stone, or as alternating patches of gold and violet, sometimes called "blended ametrine". As a member of the quartz family it is frequently flawless, though it may occasionally be found with rutile or tourmaline inclusions.

Treatments
Sometimes amethyst is partially heated in an attempt to create ametrine. Naturally occurring ametrine, if heated, may become entirely yellow, or may become greenish in color.

Principal Deposits
Ametrine will be found where amethyst and citrine are found, principally in Brazil, Colombia, Russia, Canada and the US.

Rarity
While amethyst and citrine are relatively common, ametrine is not. The best examples, showing well defined distinctive colors, are extremely difficult to find, especially in set pieces.