The world's most famous two spinels are part of the British Crown Jewels, but these beautiful red gems are traveling under an assumed name. This little-known gem is so similar to ruby that many of the great rubies of history are spinels. Case in point: the Black Prince's Ruby on the British Imperial State Crown is a magnificent 170-carat red spinel. The Timur Ruby, a 352-carat red spinel now owned by Queen Elizabeth, has the names of some of the Mogul emperors who previously owned it engraved on its face. They also thought that this magnificent red gem was ruby.

It's not surprising that ruby and spinel were long confused. Both are mined in the gem gravels of Burma and Sri Lanka. They have similar hardness and durability, vivid color, and brilliance. Ironically red spinels, often referred to in ancient texts as balas rubies , are actually more rare than ruby but, unlike ruby, they can sometimes be found in very large sizes. Balas , or Balascia , refers to Badakshan in northern Afghanistan, an active gem-producing region during the Middle Ages whose big and beautiful red to pink spinels were considered the best rubies of their time. So the spectacular “rubies” owned by Tamerlane, the Mongol conqueror, Henry VIII of England, and Peter the Great of Russia are all spinels.