Alexandrite the stone is named after Prince Alexander of Russia (which is why the "A" in Alexandrite is capitalized), who was to later become Czar Alexander II in 1855). Discovered in 1839 on the day of the prince’s birthday, Alexandrite was found in an emerald mine in the Ural Mountains of Russia.
The Alexandrite variety displays a color change (Alexandrite effect) dependent upon light, along with strong pleochroism. Alexandrite results from small scale replacement of aluminium by chromium oxide, which is responsible for Alexandrite’s characteristic green to red color change.
Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of Alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light.
The optimum or "ideal" color change would be fine emerald green to fine purplish red, but this is exceedingly rare. Because of their rarity and the color change capability, "ideal" Alexandrite gems are some of the most expensive in the world.
The finest Alexandrites were found in the Ural Mountains, the largest cut stones being in the 30 carat (6 g) range, though many fine examples have been discovered in Sri Lanka (up to 65 cts.), India (Andhra Pradesh), Brazil, Myanmar, and especially Zimbabwe (small stones usually under 1 carat (200 mg) but with intense color change). Overall, stones from any locale over 5 carats (1 g) would be considered extremely rare, especially gems with fine color change. Alexandrite is both hard and tough, making it very well suited to wear in jewelry.
Genuine Alexandrite is one of the most expensive gemstones available commercially, with the stronger color changes being more highly valued. The following are average retail prices for Alexandrite in December 2004 from The International Gem Society.
