Alexandrite is an expensive gemstone because it so rare and production has always been limited. For years, the only source for alexandrite was Russia. In the last 20 or 30 years several new discoveries of alexandrite have been reported but production of stones with a strong color change has not been significant.
Even today it is very difficult to find any fine natural alexandrites for sale anywhere. Chrysoberyl itself is already a rare gemstone normally found in small quantities in association with alluvial deposits. When we consider tthat only a very small percentage of these already rare chrysoberyls actually change color, we can begin to understand the rarity of this remarkable gemstone.
With a hardness of 8.5, alexandrite is an ideal gemstone, not only rare and beautiful but also hard and tough enough to be easily set and used in any kind of jewelry. Its historical association with the last of the Russian Tsars has created a great deal of interest and allure and everybody with even a passing interest in gemstones seems to know something about alexandrite and its unique history insuring a strong demand for alexandrites regardless of origin.