Pinkish purple, and pale Yellow in the same stone
Chalcedony Quartz SiO2
6.5 to 7
1.544 – 1.553
||May be enhanced
Brazil, Bolivia, Uruguay, Zambia, Mozambique, Tanzania, Russia, Australia
|Warnings for Care
||Colour change may occur with mild – moderate heat
Ametrine, is a naturally occurring variety of the quartz family. It is a mixture of Amethyst and Citrine with zones of purple and yellow or orange.
The colour zones visible within Ametrine are due to different oxidation states of iron within the crystal lattice, and occur as a result of a temperature gradient across the crystal during formation.
Ametrine can be the birthstone for those who are born in February or under the Zodiac sign of Pisces, as it contains both Amethyst and Citrine
Ametrine - What Causes the Colour
In Ametrine the main causal colour agent is iron, differing oxidation states (trivalent and hexavalent) produce the bi colour effect. Colours from pinkish purple, through purple to violet, are seen coupled with pale pastel yellow, yellow to golden yellow.
The best Ametrine exhibit the two colours in good but not overly saturation or intensities.
Ametrine is a daylight stone; under artificial light the subtle flashed that infuse the stone with its fire are not well displayed. The true character of the stone is best viewed in the early morning or evening, when the light is soft and warm and the majesty of this regal gem are best displayed.
A fine quality Ametrine is transparent, allowing the light to pass through the stone unhindered. Any translucency slightly weakens the passage of the light through the stone. The best quality Ametrine's are "eye-clean", being free of visible inclusions of any kind. Since Ametrine deposits are reasonably plentiful in relation to demand, there is little reason other than a price constraint to buy stones with visible inclusions.
Due to the presence of banding or zoning which delineates the distribution of colour in the crystals, Ametrine is most typically faceted in a rectangular shape with a 50/50 split of Amethyst and Citrine, though more creative cuts are becoming popular.
Almost all the worlds commercially available Ametrine comes from Bolivia, although there are lesser deposits being mined in Brazil and India.
Artificial Ametrine can be created by the differential heat treatment of Amethyst. Heat treatment at 878-1382 degrees F (470-750 degrees C) results in light yellow, golden yellow, red-brown, or green colour being produced, on the heated part of the stone. The unheated portion remains a typical Amethyst colour.
Believed to have been introduced to Europe in the 1600's by a Spanish Conquistador, this stone has only be readily available in the gem market since 1980 and as such no important or famous pieces exist.
Ametrine combines both the powers of Amethyst and Citrine in one gem. Therefore Ametrine can be the birthstone for those who are born in February or under the Zodiac sign of Pisces.