Alexandrites are color changing chrysoberyls. As a rule of thumb a chrysoberyl must show more than 50% color change to be elevated to the status of ‘alexandrite’.
The decision where 50% begins, must be left to independent gem laboratories like GIA, AIGS or IGI.
As such, alexandrite is not a stand-alone gem variety but a subset of chrysoberyls. Nevertheless, they are amongst the most famous and legendary gems.
Trouble is, they are not a quick stone to comprehend, not a fast-food gem. They need time and study, patience and good-will, not to speak of a good credit card. Even the best specimen usually displays a mix of colors due to the simple fact that light itself is always mixed, rarely pure. However, once you have entered the magic, witnessed how solid matter changes color from green to red, you are hooked for a lifetime. Watch-out!
So far, I have not heard of any treatments on alexandrite, but that does not mean somebody is not doing it somewhere and of course, there are synthetic Alexandrites, doublets, wanna-be Alexandrite (e.g. heated synthetic color-change sapphire sold as Alexandrites). For this reason, and because of the all-important separation from color shifting chrysoberyls, it is advisable not to buy an Alexandrite without gem-lab report.
Fine stones in jewelry sizes can easily sell for $10,000 per carat. Collector gems over 10 carats are a privilege of wealth.
Read about how to judge an alexandrite on photo.
We do not stock many alexandrites for the obvious reason that they bind too much capital but we have excellent contacts to Sri Lankan miners that regularly find top quality gems.
Start a hunt if you can’t find one here.
P.S. Also available: Alexandrite cat's eyes, a double whammy of magic.