By Michelle Graff
This is “Lesedi la Rona,” which means “Our Light” in Setswana, one of the official languages of Botswana. The massive rough diamond could sell for more than $70 million and yield the largest high-quality polished diamond in the world. (Photos by Donald Bowers/Getty Images for Sotheby’s)

London--The tennis-ball sized rough diamond unearthed in Botswana in November is going up for auction at Sotheby’s London in June, and it is expected to sell for more than $70 million.

Discovered at Lucara Diamond Corp.’s Karowe Mine, the 1,109.67-carat stone, named “Lesedi la Rona,” or “Our Light,” is the largest rough diamond found since the 3,016.75-carat Cullinan Diamond in 1905. (The diamond was 1,111 carats when first unearthed but lost about 2 carats during the cleaning process, which is normal, a Sotheby’s spokesperson said.)

The Cullinan yielded nine major diamonds, all of which were set in the Crown Jewels of the United Kingdom, including the 530.20-carat pear-shaped Great Star of Africa. The Star is the largest “top quality,” meaning high color and clarity, polished diamond in the world. (The world’s largest cut and polished diamond of any color is the 545.67-carat Golden Jubilee, which is a brown stone.)

But the record held by the Star could soon fall.

Sotheby’s said it commissioned independent reports on the potential yield of Lesedi la Rona from the Gem Certification and Assurance Lab (GCAL), the New York-based grading laboratory run by Don Palmieri, and Diamex Inc./Crodiam Consulting DMCC.

While the reports are not being made public at this time, a few details were released on Wednesday, including the fact that experts believe that the Lesedi la Rona could top the Great Star of Africa in size.

The reports also state that there is a “high probability” that the polished diamonds cut from the 1,109-carat rough will be D color.

20160505 Lesedi-personThe Gemological Institute of America said that the diamond’s “top color and transparency exemplify the ‘limpid’ appearance commonly associated with Type IIa diamonds,” the most chemically pure diamonds.
The Lesedi la Rona will be on view at Sotheby’s New York this coming Saturday, May 7. It will also be on view at the auction house in London between June 18 and 28.

The diamond will be offered for sale on the evening of June 29 at Sotheby’s London in an auction that’s open to the public, marking something else that’s unusual about this once-in-a-lifetime diamond find: that it’s being sold at an auction that’s open to the public, not limited to the trade.

“Every aspect of this auction is unprecedented,” David Bennett, the worldwide chairman of Sotheby’s jewelry division said. “Not only is the rough superlative in size and quality, but no rough remotely of this scale has ever been offered before at a public auction.”

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