The gem's first known owner was Abu Said, a Moorish prince of Granada in Spain in the mid-1300s. Abu Said lost the gem, as well as his crown and his life, to Don Pedro the Cruel of Seville. In 1366 Don Pedro's own brother attacked him, but Don Pedro successfully defended himself with help from the armies of the Black Prince of Bordeaux. As payment, the Black Prince demanded Don Pedro's prize jewel, and Don Pedro was in no position to argue.
How the Black Prince's Ruby came to England is unknown, but it made its next appearance in a jeweled helmet worn by the English king, Henry V, at the Battle of Agincourt in 1415. The helmet saved Henry's life when a blow from the battle-axe of the French duke of Alencon nearly destroyed it. Both the king and the helmet miraculously survived the war, and the Black Prince's Ruby remained in English hands.
Later, King James the First had the gem set into the state crown, and, despite many threats of theft, fire, and even Nazi bombs, over the centuries the Black Prince's Ruby has remained the magnificent centerpiece of the British crown, the same the Cullinan was set in.
While the Black Prince's Ruby is by far the world's most famous red spinel, it is definitely not the only one ever possessed or coveted by kings, queens, and emperors.