One of the world’s rarest diamonds was displayed in London on Tuesday by Sotheby’s auctioneers, who will put the gem up for bid next month in Geneva, The Associated Press reports.

The bright white cushion-shaped stone is the largest internally flawless diamond of D-color grade—the purest color grade—to ever appear at auction, Sotheby’s said. The diamond weighs 103.83 carats and is expected to fetch as much as $10 million during the Nov. 20 auction.

The jewel, discovered at South Africa’s Premier Mine, is only the fourth diamond of perfect color and purity weighing over 100 carats to be sold at auction, Sotheby’s said. In May 1995, the Star of the Season sold for a record $16.7 million.

Alexandra Rhodes, head of jewelry at Sotheby’s Geneva, said the estimated price of the latest gem reflected the current market.

“I think for a stone of this caliber it’s a rarity for the market and that’s the right (estimated price) for today’s market,” she said. “The person who buys it will also have the privilege of naming it.”

It took diamond cutters 18 months to plan, design, and cut the gem, and its shape is reminiscent of many famous and historic diamonds.

JCK