why does alexandrite change color
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why does alexandrite change color?
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Alexandrite
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2022-07-04T09:07:56+00:00
2022-07-04T09:07:56+00:00 2 Answers
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alexandrite is the very rare color-change variety of the mineral chrysoberyl. Often described by gem aficionados as “emerald by day, ruby by night,”，
emerald by day, ruby by night
Originally discovered in Russia’s Ural Mountains in the 1830s, it’s now found in Sri Lanka, East Africa, and Brazil, but fine material is exceptionally rare and valuable.
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Alexandrite’s color-changing properties are known as the “Alexandrite effect”, which is the result of traces of chromium found in gemstones. Like the red of ruby and the green of emerald, the absorption of blue and yellow in the spectrum by traces of chromium is the main coloring factor in the red-green transition of alexandrite.
Sunlight has a relatively flat color ratio across wavelengths, while fluorescent lamps are rich in lighter blue light and lots of yellow light. So when alexandrite is exposed to sunlight, it tends to absorb blue and yellow light more and reflect green light, which is why alexandrite appears green in sunlight. When alexandrite is exposed to fluorescent lights, it only reflects a lot of red light due to the lack of green light and the absorption of yellow and blue light by traces of chrome. This is the main reason why the color changes from green to red when alexandrite is brought from daylight to indoor fluorescent lighting.