Alexandrite

History
Alexandrite was first discovered in the Ural Mountains in 1830, and was named after Tsar Alexander II of Russia.

Features
Alexandrite is a very rare variety of chrysoberyl, and can be distinguished by its unique color change. Referred to as "emerald by day and ruby by night" alexandrite appears green in sunlight and red in incandescent or candle light. Alexandrite is frequently flawless, or only very slightly included.

Treatments
Natural alexandrites are generally untreated, however synthetic chrysoberyls are made to imitate alexandrites because of their rarity and costliness. Lab created stones tend to have excellent color change but have slightly different colors than the natural stone.

Principal Deposits
Some alexandrite is still available from the Ural mountains in Russia, but more recent deposits come from Brazil, Sri Lanka and Zimbabwe.

Rarity
Most of the recent alexandrite deposits do not show a dramatic color change, but are still somewhat rare. Alexandrite which displays strong and distinctive color change between red and green, with few or no inclusions, and is large enough to facet into respectable sized stones are extremely rare.