A variety of the mineral chrysoberyl, top quality alexandrite is very rare and very valuable. At 8.5 on the Mohs scale, its hardness is considered to be relatively good. High quality alexandrite dramatically changes color from green in fluorescent light and daylight to purplish red in incandescent light. Discovered in Russia in 1830 and named after Czar Alexander II, it was soon adopted as the national stone of Russia. Its colors correspond to the Russian imperial colors. Other forms of alexandrite are mined in Brazil, Tanzania, Sri Lanka, India and Madagascar. Alexandrite is also an alternative June birthstone in the United States.

A variety of the mineral chrysoberyl, top quality alexandrite is very rare and very valuable. At 8.5 on the Mohs scale, its hardness is considered to be relatively good. High quality alexandrite dramatically changes color from green in fluorescent light and daylight to purplish red in incandescent light. Discovered in Russia in 1830 and named after Czar Alexander II, it was soon adopted as the national stone of Russia. Its colors correspond to the Russian imperial colors. Other forms of alexandrite are mined in Brazil, Tanzania, Sri Lanka, India and Madagascar. Alexandrite is also an alternative June birthstone in the United States.