Alexandrite is named after its discovery in the Ural Mountains in 1830 on the twelfth birthday of the Russian Crown Prince (later to become Czar Alexander II). Alexandrite has also been mined in Brazil and Sri Lanka. A unique feature of this gem is that it appears green under sunlight or fluorescent light, yet changes to red or purple-red when viewed under incandescent light. Because of this color change, the Russians, whose soldiers wore red and green uniforms, assigned great value to this gem as a talisman.

As with emerald and ruby, alexandrite’s color is caused by chromium, which absorbs yellow wavelengths. Both green and red are equally present in alexandrite; when viewed under a well-balanced light such as sunlight, it appears green, changing to red or purple-red under incandescent light, in which red wavelengths predominate.

However, alexandrite’s green is not the magnificent green seen in emerald, but a rather dull green, and when compared with other gemstones the beauty grade is usually B at best. Its red is also not the purple red seen in ruby, but is more often a dull red that is closer to purple. Why, then, is alexandrite deemed so valuable? Rather than for its inherent beauty, alexandrite is valued for the rare and remarkable change of color that it possesses. Of course, the basic requirements of a pleasing appearance and freedom from imperfections are also important.

Alexandrite is a variety of the mineral chrysoberyl, and though it may be difficult to imagine, it is the same mineral as cat’s eye. Its hardness is 8 below diamond, ruby, and sapphire. It has sufficient durability as long as it is free of fractures. The photograph to the next page is an alexandrite from Brazil, a gem-quality specimen with excellent color and a good color change.