Tennis ball-sized diamond may fetch over $70mn at auction

The 1109 carat "Lesedi La Rona" diamond is displayed in a case at Sotheby's in the Manhattan borough of New York, US, May 4, 2016. © Lucas Jackson
The world’s second-biggest rough diamond is expected to sell for $70 million at an auction in London next month, according to auction house Sotheby's.

“Lesedi la Rona” (“Our Light”), the 1,109-carat diamond was found in Botswana in November. It's the size of a tennis ball and is believed to be between 2.5 billion and three billion years old.

The gem, unearthed by Canadian mining company Lucara Diamonds, is the biggest diamond discovered in more than 100 years. The company expects to get up to 48 percent of the proceeds after taxes, according to CEO William Lamb.

“There’s blue-sky potential,” Lamb told Bloomberg News talking about the possible sale price. “You only need two people that desperately want it, and then you’ll get a good price.”

He added the rough diamond could become a gem of about 400 carats once cut and polished but the company decided there was less risk and more immediate value to shareholders by selling it in its rough form.

The chairman of Sotheby's jewelry division David Bennett said the size of the diamond amazed experts.

"It really just soared off the scale of rare into something just, one off, it's just unique," Bennett told Reuters.

Lesedi La Rona is second in size only to the Cullinan Diamond, which was discovered in 1905 in South Africa and weighed more than 3,000 carats. It was later cut into nine major gemstones and 96 smaller stones. One of them, the Great Star of Africa gem, now adorns the British Royal Scepter which is on display at the Tower of London.