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October Birthstone: Opal
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October’s birthstone, the opal, symbolizes faithfulness and confidence. The word comes from the Latin opalus, meaning “precious jewel,” and from the Greek word opallios, meaning “to see a change in color.” Discover more about this month’s birthstone!
Opals are a type of quartz made up of tiny spheres of amorphous hydrated silica, which give it its rainbow shimmer.
Opal’s high water content makes it prone to cracking or crazing (many fine cracks), however. This can happen if the gem dries out, such as might occur when exposed to high temperatures or long periods of low humidity. The gem is relatively soft, with a hardness rating of only 5.5. (Never place an opal in an ultrasonic jewelry cleaner: The vibrations can crack the gem.)
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