Giant diamond doesn’t find buyer at Sotheby’s sale in London

Nothing of the size and quality of Lesedi La Rona – which measures measures 6.64 x 5.5 x 4.2cm (2.6 x 2.1 x 1.6in) – has been found in more than 100 years. Laboratory-made gem diamonds, grown using a technique called chemical vapour deposition, are emerging as rivals; these near-perfect crystals bear none of the messy ethical implications of the mined stones.

The diamond was unearthed in November in Botswana at a mine owned by Canada’s Lucara Diamond Corporation.

“The Lesedi la Rona is simply outstanding, and its discovery is the find of a lifetime”. But the industry’s reputation still needs a polish.

The name Lesedi La Rona means “our light” in the Tswana language spoken in the area where the diamond was found.

Lesedi La Rona was the single biggest diamond uncovered since the Cullinin Diamond in 1905 – a 3,106.75-carat stone.

“Every aspect of tonight’s auction was unprecedented”, Sotheby’s said in a statement: “No one alive today has ever seen a gem-quality rough diamond of this incredible scale, and no diamond – polished or rough – has ever been estimated at this price level”.

According to a study by the Gemological Institute of America, the rough diamond’s colour and transparency “exemplify” type IIA diamonds.

But a rough diamond weighting 813 carats carried a $63 million price tag at a private sale last month.

“Nobody has ever done anything like this before”, Lamb told ABC News, describing his emotions before the historic sale.

But the Sotheby’s auctioneer failed to persuade bidders to go above $61 million for the jewel, which was discovered in 2015 by the Lucara Diamond Corp.

The world’s largest uncut diamond is to be sold at a public auction this week, in a break from tradition.