Tuesday, 23 May 2017

Alexandrite

Described by gem aficionados as “emerald by day, ruby by night,” alexandrite is a very rare color-change variety of the mineral chrysoberyl.

Alexandrite deposits were first discovered in 1830 in Russia’s Ural Mountains. Those first alexandrites were of very fine quality and displayed vivid hues and dramatic color change.
The spectacular Ural Mountain deposits didn’t last, and today most alexandrite comes from Sri Lanka, East Africa, and Brazil. The newer deposits contain some fine-quality stones, but many display less-precise color change and muddier hues than the nineteenth-century Russian alexandrites.

Fine alexandrite is green to bluish green in daylight and red to purplish red in incandescent light. Alexandrite is most often available in mixed cuts. Its extreme rarity means it is often cut to save weight.
Good quality alexandrite has few inclusions. Rarely, needle-like inclusions create a cat’s-eye. Most cut gems weigh less than one carat. Larger, high quality gems rise in price dramatically.

Production from Russian mines is very limited today. Sri Lankan alexandrites are generally larger but their colors tend to be less desirable. Alexandrites from Brazil have been found in colors that rival the Russian material, but production has decreased.