The Blue Moon diamond weighing 12.03 carats, discovered in South Africa in January last year, will be exhibited in Hong Kong, London and New York before going on Sotheby's for auction in Geneva on 11 November. The Gemological Institute of America previously declared the Blue Moon to be "internally flawless" and is the largest cushion-shaped stone in that category to ever appear at auction.

“The Blue Moon diamond is a simply sensational stone of perfect colour and purity,” David Bennett, who heads Sotheby’s international jewellery division, said in a statement. Sotheby’s put its estimated sale price between US$35 to $55 million which, at the higher end, would mark a record for any diamond sale.