Diamond necklace valued at up to $2.8 million heads to auction

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."