The AGTA Gemological Testing Center is the natural coloured gemstone industry’s premier independent laboratory providing the industry and the public with a complete range of services, including gemstone identification, origin determination and pearl ide
Named after Russian Tsar Alexander II. A highly dichroic, rare variety of chrysoberyl. Emerald green in natural daylight, reddish in violet by artificial light, due to its unusual absorption properties. One of the hardest and most important gemstones. A f
American Gemological Laboratories is a unit of Collectors Universe, the leading provider of value-added authentication and grading services for high-value collectibles and gemstones, which was founded in 1986 and publicly traded since 1999. In 1977, Ameri
Several other well known gemstones, including diaspore, sapphire, garnet and spinel may also change color as a function of the light source but the color change of top alexandrites is distinctive and attractive under any light conditions.
Alexandrite cannot be improved by any kind of thermal treatment. Although some have tried, heat treatment does not seem to affect alexandrite at all. Some lower quality cracked alexandrites are oiled to hide the cracks but beyond that, alexandrite is not
The retail replacement cost for a 1ct. alexandrite could be anywhere between $500 to $12,000 per carat. The intensity of the color change and the attractiveness of the colors are the most important factors in determining the value of an alexandrite. With
It is very unlikely that even an old alexandrite ring could contain a natural alexandrite. Natural alexandrites, especially large clean stones are extremely rare and almost never available at any price. Most old inherited alexandrite rings are actually sy
Along with diamonds, rubies, and emeralds, top quality alexandrites are among the most expensive gemstones in the world. In larger sizes over 4.00 or 5.00cts., Burmese rubies are more rare and expensive than alexandrites but in sizes below 1.00cts., alexa
The mining of alexandrite in Russia lasted less than 100 years from the time it was discovered in 1833 to the early 1900’s. It was George Kunz, the gemologist/gemstone buyer for Tiffany & Co that probably did the most to popularize this unique gemst