Flawless 100-carat diamond to fetch up to $25m

A flawless, 100-carat diamond is expected to fetch up to $25 million when it goes under the hammer today at Sotheby's.

The auction house's Magnificent Jewels Sale, which takes place today at Sotheby's New York, will feature the largest emerald cut flawless diamond ever sold at auction.

"Exceedingly rare, this 100.20-carat perfect diamond is as much a masterpiece of human skill and artistry as it is a miracle of nature," says Sotheby's. "This spectacular gem has everything one could ever want in a diamond."

The auction takes place following a worldwide tour to cities such as Dubai, London and Hong Kong, which included coloured diamonds as well as Kashmir sapphire jewellery. The collection attracted admirers and investors alike, says Gary Schuler, the head of Sotheby's New York jewellery department.

"They are in awe of its size, particularly when they put it on their hand," he tells CNN. "They can't believe there's a diamond this Pure of such impressive scale."

Flawless diamonds - those free of internal defects - are extremely rare at over 100 carats, with only five other stones ever sold at auction in the past. The diamond up for sale today was first mined by De Beers in Southern Africa and weighed over 200 carats before being refined down to its current cut.

The auction follows a recent report from Barclays Wealth, which found that more than a quarter of the bank's high net worth clients have increasingly turned to "treasure assets" in the past five years, with jewellery ranking the most popular for individuals across all countries.

"People are loving them as an alternative investment," Neil Duttson, founder of high-end dealer Duttson Rocks, commented. "It’s a tangible, moveable asset, so you can carry your wealth in your pocket or on your finger."

The auction will feature more than 300 other pieces and is estimated to fetch more than $50 million in total sales, half of which could be generated by the 100-carat diamond.