Alexandrite is one of the most fascinating gemstones throughout history: a gem variety of the mineral chrysoberyl that actually changes color from green in daylight to red in incandescent light.
The first time you see it, it is hard to believe your eyes! Gems that show special optical effects are known as phenomenal stones. Chrysoberyl dominates this category, because not only is alexandrite the most spectacular color changing gem, cat's-eye chrysoberyl has the most dramatic eye. Alexandrite has a distinguished and glamorous past: it was discovered in 1830 in Czarist Russia. Since the old Russian imperial colors are red and green, it was named after Czar Alexander II on the occasion of his coming of age.
Alexandrite can be found in jewels of the period as it was well loved by the Russian master jewelers. Master gemologist George Kunz of Tiffany was a fan of alexandrite and the company produced many rings featuring fine alexandrite in the late nineteenth and early twentieth century, including some set in platinum from the twenties. Some Victorian jewelry from England features sets of small alexandrites.
Alexandrite is also sometimes available as an unset stone but it is extremely rare in fine qualities. The original source in Russia's Ural Mountains has long since closed after producing for only a few decades and only a few stones can be found on the market today. Material with a certificate of Russian origin is still particularly valued by the trade. Some alexandrite is found in Sri Lanka and Zimbabwe and Brazil but very little shows a dramatic color change. For many years, alexandrite was almost impossible to find because there was so little available.
Then in 1987, a new find of alexandrite was made in Brazil at a locality called Hematita. The Hematita alexandrite shows a striking and attractive color change from raspberry red to bluish green. Although alexandrite remains extremely rare and expensive, the production of a limited amount of new material means a new generation of jewelers and collectors have been exposed to this beautiful gemstone, creating an upsurge in popularity and demand. Alexandrite usually is not used for an engagement or bridal jewelry.
When evaluating alexandrite, pay the most attention to the color change: the more dramatic and complete the shift from red to green, without the bleeding through of brown from one color to the next, the more rare and valuable the stone. The other important value factors are the attractiveness of the two colors - the more intense the better - the clarity, and the cutting quality. Because of the rarity of this gemstone, large sizes command very high premiums.
|Alexandrite - Main Characteristics|
|Hardness (Mohs Scale)||8.5|
|Molecular formula|| BeAl2O4|
|Composition||Aluminium (Al) and Beryllium (Be) oxide,|
|Crystal Habit||One-directional, narrow formation, splits into thin flat pieces.|
|Color/Spectrum||Bleeding from golden-yellow to greenish, reddish, etc.|
|Atomic (Crystal )Structure ||AlO6 octahedra.|
|Index of Refraction||1.74-1.75|
|Uses||Jewelry, decorative art.