Alexandrite

Renowned for one of gemology's most dramatic optical effects, alexandrite shifts from emerald green in daylight to raspberry red under incandescent light, a change produced by chromium's unusual absorption of light. It is a variety of chrysoberyl, and at 8.5 on the Mohs scale it ranks among the harder gem materials, durable enough for daily wear. The stone was first found in Russia's Ural Mountains in 1830 and named for Tsar Alexander II. Fine examples number among the rarest and most valuable of all gems, and although Brazil, Sri Lanka, and East Africa now supply most of the market, stones matching the original Russian standard remain extraordinarily scarce. Sri Lankan localities such as Ratnapura continue to yield notable material. A semi-precious species that reaches the fine price tier, alexandrite also serves as a modern June birthstone.