An “exceptionally rare” pink diamond, named the Williamson Pink Star in a nod to a similar precious stone owned by the Queen, is expected to sell for more than 21 million dollars (£18 million) this autumn.
The 11.15 carat cushion-shaped stone is the second largest internally flawless fancy vivid pink diamond to ever appear at auction and could set a new per carat price record at auction, Sotheby’s said.
