Very scarce and rarely seen in large faceted specimens, Alexandrite is truly a remarkable gemstone. Depending on the lighting conditions, Alexandrite can appear green or purplish red. Alexandrite has aptly been described as being “Emerald by day, ruby by night.”
When viewed in daylight or fluorescent light, Alexandrite will appear green. Incandescent light or candlelight will cause the stone to assume a red appearance. The reason for this color change is due to the light absorption properties of Alexandrite.
It wasn’t until the early 1830s, that Alexandrite first saw the light of day. An emerald mine in the Ural Mountains of Russia also had stones which at first glance were emeralds, but underwent a chameleon-like color change to red, when viewed under candlelight. The stones were also much harder than emeralds. The colors green and red were the military colors of Russia, making the stones very popular with Tsar’s family; fittingly, the stone was named Alexandrite, on the occasion of the coming of age of Alexander II, who later became Tsar of Russia.
Alexandrite is a variety of chrysoberyl, which has a chemical formula of BeAl2O4. It should be noted that chrysoberyl and beryl are unrelated minerals, despite the closeness of their names; both minerals contain the element beryllium. With a Mohs hardness of 8.5, Chrysoberyl is considerably harder than beryl.
As noted, Alexandrite is an extremely rare gemstone, because it is found in just a few localities. Russian Alexandrite is considered the finest quality, in terms of coloration; due to depletion of supply, production of Alexandrite in Russia virtually ceased in the early twentieth century. In the late twentieth century, Alexandrite was discovered in Brazil; Alexandrite can also be found in Sri Lanka, Madagascar, and Tanzania.
Alexandrite is one of three recognized birthstones for June; the others are pearl and moonstone.
(Photo courtesy of GIA)
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