The Blue, the world's largest flawless fancy vivid blue diamond is set to go under hammer next month and the experts have predicted it to fetch up to 15 million pounds to 21 million dollars.
Christie's New York is set to auction the 13.22 carat diamond, Sky News reported.
Rahul Kadakia, Head of Jewellery for Christie's Americas and Switzerland, said the stone is internally and externally bereft of any imperfections, asserting that it was the best blue diamond in the world.
Christie's didn't reveal the owner's name bust sad that he had the diamond in his possession for a long time.
Also up for auction is the 'The Rajah' diamond, which is believed to have been purchased from India by Tiffany and Co in the 19th Century; pundits have estimated it to fetch between 1.8 million pounds and 3 million pounds.