Alexandrite is the extremely rare colour change variety of Chrysoberyl. Originally found in the Ural Mountains of Russia and named after Czar Alexander II. Alexandrite has historically been one of the most sought after gems; although its rarity has made the price sometimes prohibitive. Alexandrite has a hardness of 8.5 on Mohs scale and is the birthstone for June and the gem for 55th anniversaries.
Greenish in daylight and purplish red to red in incandescent light the colour change is rarely seen in other gems apart from colour change Garnet and sometimes Sapphire. Alexandrite is sporadically mined in Southern India, Sri Lanka, Madagascar and Brazil. The price of Alexandrite is determined by size, colour, clarity and the intensity of the colour change. Fine quality Alexandrites reach amazing prices on the world market.
Synthetic Alexandrite is being produced and a purplish synthetic corundum (sapphire) is used to imitate Alexandrite. These were often bought back from Egypt and Africa by soldiers returning from war believing they had a natural Alexandrite. We have seen these synthetic stones for sale as Alexandrite in tourist shops overseas.
Alexandrite is doubly refractive with an RI of 1.745 -1.759 and the specific gravity of Alexandrite is 3.71-3.75.