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Alexandrite is one of the rarest gems on earth. It's hardness and unique color change property make it one of the most sought after gems. For centuries Russia produced nearly all the gem grade material found in the market. The lack of easily accessable facet grade rough caused a depletion of new gems in the market prior to the 21st century. During this period, the price for clean material was so astronomical the market came to a near standstill. Recently new mines in Africa, Brazil and India are producing material, some of which rival the old Russian goods. The Brazilian material is generally known as the better color change, but also predominantly heavily included. The India gems are more often clean, but many have extremely weak color change. The abundance of new material has brought the price down considerably, especially for small melee rounds. All sources have their premium larger goods which still command a high price.
The color change is the distinctive property that distinguishes other Chrysoberyl from Alexandrite. If there is no color change, it is not Alexandrite. The distinctness of the color change is the most significant factor in price. The most sought after color change is a gem that has a teal tone in natural sunlight and changes to a red in artificial light. Most tend to be greenish changing to pink.
As with most valuable gem varieties, there are many synthetics that have been made to imitate the Alexandrite. The best and most expensive of these is the lab grown Alexandrite. This material shows the premium color change from teal to red and its change is quite distinct. This material has essentially the same physical properites of its natural counterpart. These gems will cost much more than other imitations, but if you want the look and feel of a real Alexandrite, it is well worth the expense. Another synthetic worthy of discussion is the color change lab Sapphire. The colors tend to blend in this material and therefore the overall stone has a dirtier look, but of all the lower cost imitations in the market it is the best.