A 19.51-carat platinum and diamond ring, produced by renowned jeweller Harry Winston, will provide the star lot of Sotheby's September 24 jewellery auction in New York.

'Sure to generate early excitement in the global jewelry market this auction season'

The piece, which comes from the collection of philanthropist George Rothman, is expected to make up to $1.8m.

Gary Schuler, the director of Sotheby's New York jewellery department, comments: "This diamond is the caliber of stone that is sure to generate early excitement in the global jewelry market this auction season."

The sale will also feature a $300,000-valued Schlumberger platinum and diamond pendant brooch, as well as an 18-karat gold Rene Boivin dog brooch, estimated at $90,000.

These are exciting times for Sotheby's jewellery department. The Premier Blue, the world's largest fancy blue diamond, could be set to make $19m at Sotheby's Hong Kong on October 7.

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