Alexandrite – (Gemstone Jewelry)

TheAntiqueTrade.co.uk Glossary of Antique Terms

Alexandrite – (Gemstone, Jewelry) in alexandrite is a semi-precious gemstone Alexandrite, which is a greenish brown and exhibits red highlights under certain lights. The stone was first discovered in the Ural Mountains of Russia in 1830 during the reign of Czar Alexander II - hence the name.

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TheAntiqueTrade said...

Alexandrite is a green form of Chrysoberyl. The alexandrite variety displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. This color shift is independent of any change of hue with viewing direction through the crystal that would arise from pleochroism. Both these different properties are frequently referred to as "color change", however. Alexandrite results from small scale replacement of aluminium by chromium ions in the crystal structure, which causes intense absorption of light over a narrow range of wavelengths in the yellow region of the spectrum. Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The optimum or "ideal" color change would be fine emerald green to fine purplish red, but this is exceedingly rare. Because of their rarity and the color change capability, "ideal" alexandrite gems are some of the most expensive in the world.

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