Tennis-ball sized diamond found by Canadian firm could fetch $90M

A Sotherby's employee holds Lesedi La Rona Diamond on May 3, 2016 in New York City. (Donald Bowers / Getty Images for Sotheby's, via AP)

A three-billion-year-old diamond the size of a tennis ball could fetch more than C$90 million when the Canadian mining company that unearthed it puts the rock up for auction this summer.

But the first person to lay eyes on the whopping gem barely gave it a glance, the CEO of Vancouver-based Lucara Diamond Corp. recalled Wednesday, as the eye-popping estimate for the precious stone was issued by auctioneer Sotheby's.

"He'd only been working for us for two weeks, so he sees the thousand carats and goes 'oh, this must be normal,"' William Lamb told The Canadian Press. "He didn't tell anybody. It was only when the chief saw it that there was this huge commotion on site."

The diamond was unearthed in November, at the Karowe mine in Botswana that's owned by Lucara (TSX:LUC).

After being closely examined, it was found to measure 1,109 carats, making it the second-largest gem-quality rough diamond ever discovered.

The only bigger diamond found to date was the 3,106-carat Cullinan diamond, unearthed in South Africa in 1905. It was cut into nine pieces that form part of the U.K. Crown Jewels.

The Cullinan diamond, however, was found when a mine worker noticed something glinting in the side of a pit, grabbed a ladder and started chipping around it with a pen knife, said Lamb.

The diamond found at the Lucara mine, in contrast, managed to survive a modern mining process which included drilling, blasting, excavation, crushing and mechanized sorting, he said.

"Our stone actually went through an entire processing facility before it was recovered," Lamb explained. "We were very lucky."

The diamond has been named Lesedi la Rona, meaning "our light" in the local Tswana language.

The name came from a local contest which drew some 11,000 entries, Lamb said, and carries a special meaning for Botswana, whose economy has benefited greatly from diamond mining.

The Lesedi la Rona is currently on a world tour ahead of an auction in London this summer.

It has already been displayed in Singapore, Hong Kong and Dubai, and will be shown in New York this weekend before heading to locations in Europe, said Lamb.

"We're trying to get access to people who may want it as a collector's item," he said. "We're looking at people who have the financial resources, but also see the uniqueness, the rarity and the beauty in the stone."

Auctioneer Sotheby's has estimated the diamond could sell for more than C$90 million, but Lamb said just how much the rock will ultimately go for is hard to say.

"This is historic," he said. "It is the only plus thousand carat stone in existence."

Whoever acquires the diamond will have to decide whether to cut and polish the stone, possibly splitting it into smaller pieces, or keep it in its rough form.

"If you ask me, I wouldn't cut it. It is unique," said Lamb, who remembered feeling "shock and awe" when he first held the diamond.

"It automatically draws you to it. I'd say the stone has an addictive quality to it."

Sotheby's has said the rough gemstone "of exceptional transparency" could yield the largest top-quality diamond ever cut and polished, if the buyer decides to go that route.

David Bennett, chairman of Sotheby's jewelry division, called the discovery "the find of a lifetime" and the auction unprecedented, because no rough diamond of this size has ever been auctioned.

The Lesedi la Rona could smash the record price for a diamond of US$48.5 million, paid at a Geneva sale last year for the 12.03-carat polished "Blue Moon" diamond. Hong Kong billionaire Joseph Lau picked it up as a gift for his 7-year-old daughter.

The Lesedi la Rona diamond will be offered at auction on June 29.

With files from The Associated Press