Black Prince's Ruby

The Black Prince's Ruby is a large, irregular cabochon red spinel weighing 170 carats (34 g) set in the cross pattée above the Cullinan II diamond at the front of the Imperial State Crown of the United Kingdom.

The stone is believed to have been mined in Badakhshan in present day Afghanistan,[3] the principal source of large spinel gems in the Middle Ages.

Lacking the power to put down the revolt unaided, Don Pedro made an alliance with the Black Prince, the son of Edward III of England.

The Black Prince took part in the Battle of Nájera, and apparently demanded the ruby in exchange for the services he had rendered.

[7][8] During his campaign in France, Henry V of England wore a gem-encrusted helmet that included the Black Prince's Ruby.

How the stone found its way back into the Royal Collection after the Interregnum is unclear, but a substantial "ruby" was acquired for the Crown Jewels in 1661 at a cost of £400, and this may well have been the spinel.

The Queen can be clearly seen wearing the jewel in the Imperial State Crown in her official coronation portrait by Sir George Hayter.