A rare diamond necklace with possible links to former French queen consort Marie Antoinette is to be auctioned in November with a price estimate of up to $2.8 million.

The 18th century jewel, weighing 300 carats, was made in the decade before the 1789 French Revolution and was last seen in public in 1973 before being sold into a private collection.

Made up of three rows of diamonds with diamond tassels at each end, the piece went on public display for the first time in 50 years on Monday at Sotheby’s London showrooms.

“Diamonds were always repurposed and because the mines of Golconda in India went extinct at the end of the 18th century, most of the 18th century jewels, in order to keep with fashion, were broken up,” Andres White Correal, Chairman and Head of the Royal and Noble Sales at Sotheby’s for Europe and the Middle East, told Reuters.

“So to have an 18th century jewel intact of this magnitude, size and the importance of the diamonds, is exceptionally rare.”

It is thought some of its diamonds may have come from the infamous “Affair of the Diamond Necklace” piece that tarnished the reputation of Marie Antoinette, the unpopular last queen consort of France before the French Revolution.

The necklace did belong to the Marquesses of Anglesey, an Anglo-Welsh aristocratic family, with members wearing it to the coronations of King George VI in 1937 and Queen Elizabeth in 1953.

The necklace will be offered for sale at Sotheby’s “Royal & Noble Jewels” sale in Geneva on Nov. 11.