Traditionally February’s birthstone, Amethyst is a variety of Quartz that is transparent and crystalline, usually deep purple to pale bluish-violet; the hues are sometimes mingled in the same stone, owing to irregular color zoning, and some show patches of yellow. Other colors are reddish-mauve (Siberian stones), reddish-violet (Uruguayan stones) or grey-mauve (Mexican stones).
Specimens containing inclusions of goethite or other fibrous minerals are polished as cats eye’s. Amethysts have been set in globular or pear-shaped pendants and as pierced beads for necklaces and ear-drops. Some large stones have been embellished by having set into them a design of small diamonds.
Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglio engraved gems.
For centuries, people have believed this mystical stone possesses healing power: The Greeks believed amethyst gems could prevent intoxication, while medieval European soldiers wore amethyst amulets as protection in battle in the belief that amethysts heal people and keep them cool-headed. Beads of amethyst were found in Anglo-Saxon graves in England.
In the 19th century, the color of amethyst was attributed to the presence of manganese. However, since it is capable of being greatly altered and even discharged by heat, the color was believed by some authorities to be from an organic source. Ferric thiocyanate has been suggested, and sulfur was said to have been detected in the mineral.
When natural amethysts (not the variety from Madagascar) are heated, the color changes to pale yellow (sometimes then mistaken for Citrine, but distinguishable by its dichroism); when the heat is increased, it changes to dark yellow or reddish-brown and, when increased further, to milky white. Some Brazilian amethysts when heated change color to green.