Spinel
“The gem mistaken for ruby”
Spinel is a hard, brilliant mineral that occurs in nearly every color, with red spinel being the most famous — and most historically confused with ruby. For centuries, the world's most celebrated 'rubies' were actually spinels, including some of the most famous stones in royal crown jewels.
magnesium aluminum oxide (MgAl₂O₄)
Mogok (Myanmar), Tajikistan, Sri Lanka, Tanzania, Vietnam, Mahenge (Tanzania — neon pink)
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The 'Black Prince's Ruby' in the British Imperial State Crown and the 'Timur Ruby' in the Crown Jewels are both actually red spinels — their true identity wasn't confirmed until modern gemology developed.
Test Your Knowledge
How were many famous 'rubies' in royal crown jewels eventually identified as red spinel?
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