Rare blue diamond could fetch £24.7m at auction

Sotheby’s is set to auction the world’s largest oval fancy vivid blue diamond ever to go under the hammer.

The De Beers ‘Millennium Jewel 4’ – set to be auctioned at Sotheby’s Magnificent Jewels and Jadeite Spring Sale on 5 April, 2016 – is expected to sell for between $30m and $35m (£21.1m to £24.7m).

Offered for sale from an Asian private collection, the jewel is the only oval-shaped stone among the 12 rare diamonds – 11 blue and one colourless – that form the De Beers Millennium Jewels collection unveiled in 2000.

The stone will be displayed in New York, London, Geneva, Singapore, Taipei and Hong Kong before it is auctioned at the Hong Kong Convention and Exhibition Centre.

Tom Moses, executive vice-president and chief research and laboratory officer at the GIA, said: “Blue diamonds of any intensity of colour are amongst the rarest of all gems. Highly saturated blue diamonds over 10 carats combined with an Internally Flawless clarity grade are extremely rare.

“There have been fewer and fewer new rough diamonds discovered over the last decade that produce this colour. Most of the recent diamonds offered for sale in this category are coming from private collections – not diamond mines.”