Sotheby’s Geneva will auction the legendary Beau Sancy Diamond—a stone passed down through four royal families—during the Magnificent Jewels and Noble Jewels sale May 15.
 
Previously owned by French, English, and Prussian royalty, the 34.98 ct. double rose-cut diamond has an estimated value of $2 million–$4 million. Although the diamond has previously been described as flawless and colorless, a Sotheby’s release did not specify its color or clarity. The company did not respond to a request for comment at press time.

The diamond has been owned for the last 300 years by the House of Prussia, passed down through four generations. According to a Danish newspaper, the stone is currently owned by 36-year-old Prince Georg Friedrich, great-great-grandson of the final German Kaiser. 

The diamond, which has been shown publicly only four times in the last 50 years, will be showcased in an international tour before appearing in the Geneva auction in May. 

Believed to have been discovered in the 1500s, the Beau Sancy most likely originated from the mines in India near the city of Golconda, the source of history’s best-known diamonds, including the Hope, the Koh-i-Noor, and the Regent.  

In 1604, Henry IV gifted it to his wife Marie de Médicis, who wore it at her coronation as Queen of France in 1610. Following Henry IV’s assassination, the Queen escaped to the Netherlands. Heavily in debt, she was pawned her possessions and the Beau Sancy was acquired by Prince Frederick Hendrick of Orange-Nassau. That same year, the diamond was used to seal the wedding of Frederick Hendrick’s son, Willem, to Mary Stuart, daughter of Charles I of England and Henriette-Marie of France and granddaughter of Marie de Médicis.

After the death of her husband, Mary Stuart embarked for England. In 1662, the Beau Sancy was pawned to settle her debts. In 1677, her family reacquired it, and when Willem III married Mary II Stuart, daughter of King James II of England, and ascended to the British throne, the diamond became part of the collection of the Queen of England, before eventually landing in the House of Prussia.

“The Beau Sancy is one of the most fascinating and romantic gems ever to appear at auction and it is an immense privilege for Sotheby’s to handle the sale,” David Bennett, chairman of Sotheby’s jewellery department in Europe and the Middle East, and co-chairman of Sotheby’s Switzerland, said in a statement.

JCK