A relatively modern gemstone, alexandrite was discovered in Russian emerald mines located in the Ural Mountains. Legends claim that it was discovered in 1834 on the same day that future Russian Czar Alexander II came of age; it was named to honor him.
Often described as “emerald by day, ruby by night,” alexandrite is a rare variety of the mineral chrysoberyl that changes color from bluish green in daylight to purplish red under incandescent light.
This chameleon-like color shift is the result of its uncommon chemical composition which includes traces of chromium, the same coloring agent found in emerald. The unlikelihood of these elements combining under the right conditions makes alexandrite one of the rarest and most expensive gemstones on Earth.
The alexandrite mined from Russia’s famed deposits set the quality standard for this gemstone. Today, most alexandrite comes from Sri Lanka, Brazil, and East Africa, generally paling in comparison to the vivid colors of Russian gemstones.
With a hardness of 8.5 on the Mohs scale, alexandrite is softer than sapphire and harder than garnet—the other gemstones that can change color. However, due to its scarcity, alexandrite is more valuable than most gemstones, including rubies and diamonds.
Want to invest in an alexandrite piece? Find an American Gem Society jeweler near you.