The Black Prince's Ruby is a large, red gemstone called a spinel. It weighs 170 carats (34 grams) and is placed in the cross pattée, which is part of the Imperial State Crown of the United Kingdom. This cross pattée is located above the Cullinan II diamond at the front of the crown.
The spinel is one of the oldest gems in the Crown Jewels of the United Kingdom. Its history begins in the mid-14th century. A story from the 1760s says the stone was given to the Prince of Wales, Edward of Woodstock, known as the "Black Prince," by the Spanish king Peter of Castile in 1367. It is believed that Henry V wore the stone during the Battle of Agincourt in 1415. The gem is thought to have been mined in Badakhshan, which is now part of Afghanistan. This region was the main source of large spinel gems during the Middle Ages.
Spinel
The Black Prince's Ruby has a weight of 170 carats (34 grams) and measures about 4.3 centimetres (1 and three-quarters inches) in length. In the past, all red gemstones were called rubies or "balas rubies." Scientists first discovered in 1783 that spinels are chemically different from rubies. Both types of gemstones contain aluminum and oxygen, and both get their color from chromium(III). However, spinels also contain magnesium, which rubies do not have.
History
The Black Prince's Ruby is believed to have been owned by Abū Sa'īd, an Arab Muslim prince who ruled the Kingdom of Granada in the 14th century. At that time, Castile was moving its power to Seville, and the Moorish Kingdom of Granada was being attacked repeatedly as part of the Christian Reconquest of the Iberian Peninsula. Abū Sa'īd faced challenges from Peter of Castile, also known as Don Pedro the Cruel or Don Pedro the Just. Historical records suggest that Abū Sa'īd wanted to surrender to Don Pedro but did not clearly state his conditions. Don Pedro welcomed him to Seville, likely because he wanted Abū Sa'īd's wealth. When they met, Don Pedro ordered the killing of Abū Sa'īd's servants and may have personally killed him. After Abū Sa'īd's death, the ruby was discovered on his body and added to Don Pedro's possessions.
In 1366, Don Pedro's illegitimate brother, Henry of Trastámara, rebelled against him. Unable to stop the rebellion alone, Don Pedro formed an alliance with the Black Prince, the son of Edward III of England. The Black Prince fought in the Battle of Nájera and reportedly asked for the ruby in exchange for his help. Although he struggled to get money from Don Pedro, he returned to England with gemstones and Don Pedro's two daughters, Dona Constanza and Dona Isabel of Castile. The daughters were later married to the Black Prince's brothers. It is believed the ruby went to England at this time, but it is not mentioned in records until 1415, when Henry V of England wore it in a gem-encrusted helmet.
During the Battle of Agincourt in 1415, Henry V was struck on the head by a French soldier with a battleaxe. He nearly lost his life and his helmet, but his forces won the battle, and the ruby was saved. Richard III is said to have worn the ruby in his helmet during the Battle of Bosworth in 1485, where he was killed.
In 1521, Henry VIII's inventory listed a large "balas ruby" in the Tudor Crown, which is thought to be the Black Prince's Ruby. The ruby remained in the crown until the monarchy was briefly ended in the 17th century. During this time, royal crowns were taken apart, and gems were sold, with the gold melted into coins. It is unclear how the ruby returned to the Royal Collection, but a ruby was purchased for the Crown Jewels in 1661 for £400, possibly the same stone. In 1838, Queen Victoria was crowned with a new Imperial State Crown that included the ruby. The ruby is visible in her official coronation portrait. The crown was redesigned in 1937 to be lighter. A small plate on the back of the ruby marks its history.