One of the most fascinating gemstones throughout history is alexandrite: a gem variety of the mineral chrysoberyl that actually changes colour 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 colour-change gem, it has the most dramatic eye. Alexandrite has a distinguished and glamorous past and was discovered in 1830 in Russia. Since the old Russian imperial colours 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.
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, Zimbabwe and Brazil but very little shows a dramatic colour 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 colour 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.
When evaluating an alexandrite, pay the most attention to the colour change: the more dramatic and complete the shift from red to green, without the bleeding through of brown from one colour to the next, the more rare and valuable the stone. The other important value factors are the attractiveness of the two colours - the more intense the better - the clarity, and the cutting quality. Because of the rarity of this gemstone, large sizes command very high premiums.