Amethyst gem stone

Amethyst is a violet variety of transparent or semitransparent quartz of different density
of shades from almost transparent pale-violet, bluish-violet to dark violet, almost black.
The color of this gem stone is stipulate by the structural compounding of Iron.
Amethyst is a splendid jewel, widely used in industry and favorite with artists.
Amethysts are used for faceting inserts for earring, rings, and beads.
The brushes of tiny amethyst crystals are used as a souvenir semi-precious stone.
Amethyst varies in colors from almost transparent pale violet, pinkish-bluish-violet,
bluish-violet to purple, darkish-purple, and lavender-blue, sometimes almost to black. Sometimes you can see violet-smoky colored amethyst with alternating smoky and amethyst colors. The distribution of coloring is usually uneven.
Zoning of coloring is common. The most intensive coloring is usually concentrated
at the very point of the head. The experienced diamond cutter takes this circumstance during processing the stone by all means and strives that the zone with the best coloring be situated in the pin of the faceting.
Once it was counted amethyst color nature is stipulated by the compounding
of manganese (due to resemblance of gem's color to potassium permanganate color), iron, titan, cobalt and nickel. But lately it was found that violet coloring of amethyst is stipulated by multivalent ions of iron and defects in the crystal lattice of the mineral.
The defects of the crystal lattice are the deviations from ideal spatial periodicity in its real structure. Exposed to the energy of the direct sunlight the order of these defects is being destructed and amethyst can eventually lose its coloring and turn into simple transparent or pale colored quartz. Amethyst crystals often contain liquid, gas liquid and mineral inclusions (magnetite, getit, hematite, rutile, bituminous buildups). In contrast to ordinary quartz, prismatic facets on amethyst crystals are found rarely. Rather often amethyst crystals have rhombohedron facets. Besides ordinary forms inherent in quartz, amethyst frequently possesses a form resembling a scepter or mace. Being exposed to sunlight or when heated amethyst gradually loses its primary color and becomes colorless or yellow. Colorless amethysts exposed to X-rays restore their coloring. When heated
to 300 degrees of Celsius amethyst loses its violet color completely and turns into colorless quartz or totally transparent green stone, named praseolit.
A huge mass of ore was found near the city of Sodankule (Northern Finland). It was sprinkled with two hundred violet crystals of amethyst, the largest of which weighed 650 kilograms. It is so costly that the specialist cannot tell its estimated price.
Amethyst is found in the form of separate crystals, their junctions, and druses. The sizes of crystals vary from several millimeters to tens of centimeters. The crystals usually unevenly colored and the intensity of the coloring increase from the basing to the head
of the crystal. Sometimes you may find crystals colored by zones and sectors. Being exposed to sunlight (ultra violet rays) amethyst gradually turns into rock crystal. When exposed to X-rays amethyst restores it color. When heated amethyst turns yellow or greenish-yellow and turns into another variety of quartz - citrine. Amethyst is scratch-proof and is steady against abrasive action of usual dust.
In Washington there is a huge amethyst that weighs 1362 carats. Three wonderfully faceted amethysts are kept in the Gallery of minerals of British Museum of natural History. One of them that has an oval form and weighs 343 carats was found in Brazil. The other two (90 and 75 carats) were brought from Russia. One of the biggest amethysts of the world decorates the English crown. High-ranking pastors and princes like to decorate their mitres, kamelaukions and klobuks by this violet precious stone. They also must wear amethyst rings.
In recent years, decorative collection pieces of ore with amethyst in the form of druses and geodes decorate not only the museum expositions and mineralogical collections, but also modern interiors. The size of the largest amethyst geodes, for example, from Brazil, reaches two meters and more. This exotic nature marvel will ideally blend with interior. During last decades the technology of artificial growing of large amethyst crystals has been mastered and it becomes hard to distinguish between artificial and natural amethysts. This can be done only with the appliance of special methods as well as basing on their thermal conductivity. Even an experienced specialist finds it difficult to distinguish the artificial amethyst from natural ones.