Black Prince's Ruby

The Black Prince's Ruby is not a ruby at all. It is a 170 carat irregular cabochon of red spinel, about 4.3 cm long, set in the cross pattee at the front of the Imperial State Crown, directly above the Cullinan II diamond. Spinel was only chemically distinguished from ruby in 1783, long after the stone was named. It is believed to have been mined in Badakhshan, the principal medieval source of large spinels, and is displayed in the Jewel House at the Tower of London.

Its documented history begins in 14th century Spain with Abu Sa'id, a Muslim prince of Granada, who was killed in Seville around 1362 on the orders of Pedro of Castile, after which the stone entered Pedro's possession. In 1367 Pedro gave it to Edward the Black Prince, son of Edward III of England, as payment for military support at the Battle of Najera. The stone then disappears from the records until 1415.

Tradition holds that Henry V wore it in his helmet at Agincourt in 1415 and that Richard III wore it at Bosworth in 1485, though both stories rest on later accounts. The crown jewels were broken up and sold under the Commonwealth; a large ruby bought back for 400 pounds in 1661 may well have been this spinel. Queen Victoria wore it at the front of her new Imperial State Crown at her 1838 coronation, and it has stayed at the front of the crown ever since.