One of the world's rarest diamonds, about the size of an egg or a large lollipop, is going up for auction next month and is expected to fetch $12 million to $30m (Dh44m to Dh100m). Sotheby's said on Thursday, September 10, that the 102.39-carat diamond, a flawless white sparkler, was the second-largest oval diamond of its kind to be offered at auction. The largest, a 118.28-carat diamond, set a record $30.8 million price when it was sold in 2013. Only seven such diamonds, known in the trade as D colour flawless or internally flawless white diamonds, with over 100 carats have previously been sold at auction. "More and more people have come to understand that something billions of years old and of the size of a lollipop can store as much value as a Rembrandt self-portrait or a Basquiat," Gary Schuler, worldwide chairman of jewellery at Sotheby's, said in a statement. The diamond will be sold in a single-lot action without a reserve price at Sotheby's in Hong Kong on Monday, October 5. "Diamonds of this caliber and size have sold anywhere between $11.9 million to $33.7 million," said Quig Bruning, head of Sotheby's New York jewellery department. Sotheby's said the gem was cut from a 271-carat rough that was discovered at the Victor Mine in the Canadian province of Ontario in 2018 and cut and polished for more than a year. Two of the most famous large diamonds, the Koh-i-Noor and The Cullinan 1, belong to the British monarchy and form part of the British Crown Jewels. The world record for any diamond or jewel sold at auction was set in 2017 when a 59.60-carat fancy vivid pink diamond was sold for $71.2 million to the Hong Kong jewellery company Chow Tai Fook, Sotheby's said.