The Black Prince's Ruby is one of the most famous members of the British Crown jewels, but despite its name, the stone is not a ruby. The Black Prince's Ruby is actually a deep red un-faceted spinel. The Black Prince's Ruby was believed to have been mined in the 14th century somewhere from present-day Tajikistan, which was then known as Badakshan. The stone belonged to Prince Abu Sa'id of the Moorish Kingdom of Granada.