Beau Sancy stone expected to fetch £2.5 million

One of the world's oldest, rarest, and most coveted diamonds is going up for auction at Sotheby's.

Mail Online reports the 'Beau Sancy' diamond, cut in the 16th Century and weighing in at 35-carats, is expected to sell for £2.5 million.

The gem from the Eastern Deccan region of India has a rare pear cut and features 110 identical and symmetrical facets. It is thought to be the first Indian diamond in Europe.

Mail Online has Sotheby's jewelry chairman David Bennett explaining some of the history and signficance behind the Beau Sancy:

When it was made in the 16th century, the pear cut was new, bold, and so it became the most sought-after jewel of its era. Before the 'Beau Sancy' all diamonds were rudimentary.’

Such was the diamond's fame that in 1604, French King Henri IV purchased it from the first owner, the Lord of Sancy, as a gift for his glamorous wife, Marie de Medici, one of Europe's richest women.

Following the king's murder, she fell into poverty and was forced to sell the jewel, which was cut from the famous gem mines in the Indian city of Golconda.

The diamond eventually made its way through four royal European families, including England's House of Orange. Its most recent owners are the descendants of the last emperor of Germany.