The Alexandrite is a rare variety of chrysoberyl, which has so frequently the phenomenon of iridescence, showing red when illuminated with artificial light and green when illuminated with natural light.
The effect is due to the replacement, in small part, of aluminum and chromium. The same impurities of chromium are also present in corundum (which in this case is called ruby) and in the emerald.
Even in the latter case the chromium is due to an effect of iridescence: the light appears to the emerald green, while UV light appears red fluorescence ...
Discovered by mineralogist Nordenskjold in Russia on the slopes of the Ural Mountains in 1831, on the birthday of Alexander II of Russia, was called by the name of the Tsar.
It has become the Russian national gem because of its colors (red and green) are those of Holy Russia.
His major fields are currently in Brazil, Zimbabwe and Russia.
This extremely rare semi-precious stone, the value of which sometimes exceeds that of diamond, it changes color depending on the light: it appears emerald green in daylight and dark red in artificial light.
It can be cut gem and samples that show evidence of iridescence may have very high prices.
Used in high jewelry, is, for its beauty, hardness and rarity, one of the more expensive stones on the market and its price increases as the iridescence is visible (the inclusions affect less on price).
It has a fairly high hardness of 8.5 on the Mohs scale. Among its therapeutic uses, is used to control the emotions, disorders of the pancreas and strengthens sensuality and sexuality '.