Hugh Diamond Found in Botswana

by Ken Rock, MSDC Newsletter Editor

Sources: The Guardian, June 16, 2021; National Jeweler, June 24, 2021, Graff website:

One of the world's largest diamonds was unearthed in June 2021 in Botswana, Africa's largest producer of diamonds. The stone, weighing 1,098 carats, was shown to President Mokgweetsi Masisi, two weeks after the diamond firm, Debswana, unearthed it. The gem is only slightly less heavy than the world's second-largest diamond which was also found in Botswana in 2015.

"This is the largest diamond to be recovered by Debswana in its history of over 50 years in operation," said Lynette Armstrong, Debswana Diamond Company's acting managing director. "From our preliminary analysis it could be the world's third largest gem quality stone."

The discovery was made at the Jwaneng mine, around 75 miles from the country's capital, Gaborone. The mine is operated by Debswana, a joint venture between the government and global diamond giant De Beers.  As much as 80 percent of the income from sales goes to state coffers through dividends, royalties and taxes. An official government Twitter account noted that "proceeds from the diamond will be used to advance national development in the country." Officially opened in 1982, the Jwaneng mine usually yields between 12.5 million and 15 million carats of diamonds a year, according to Debswana. The June find is the largest gem unearthed by the company since diamonds were first discovered in Botswana in 1967, the government said.

Botswana's Minerals Minister, Lefoko Moagi, said the latest find could not have come at a better time for Botswana after the pandemic caused diamond sales to slump last year. The newly discovered stone is yet to be named. Ms Armstrong said a decision had not yet been taken on whether to sell the "rare and extraordinary stone" through De Beers or through the state-owned Okavango Diamond Company.  An estimate of the value of the find is not readily available.

Other Large Diamonds from Botswana

The second largest gem-quality diamond from Botswana is believed to be the “Lesedi La Rona,” a 1,109-carat stone found in 2015 by Canadian firm Lucara Diamond at the Karowe mine, also in Botswana. The diamond was sold to luxury jeweler Graff Diamonds in 2017 for $53 million.  The stone is believed to have been formed between 2.5 and 3 billion years ago and is roughly the size of a tennis ball.  The name “Lesedi La Rona” means “our light” in Botswana’s Tswana language.

Lucara Diamond Corp. found this 1,109-carat rough diamond, later dubbed “Lesedi La Rona,” at the Karowe Mine in Botswana in November 2015. On Monday, the company announced that it had found a buyer for the stone--Graff Diamonds.

The company says it will be scanned using state-of-the-art 3D equipment that searches for inclusions, small imperfections in the heart of the stone, to decide how the diamond will be polished. Then an expert team will examine the diamond using microscopes to pick up and navigate any further pinpoint inclusions. They will then work out how to cut the diamond and into how many individual stones.

“Cutting a diamond of this size is an art form, the ultimate art of sculpture,” Laurence Graff, founder of Graff Diamonds, said in a statement. “It is the riskiest form of art, because you can never add and you can never cover up a mistake; you can only take away. You have to be careful and you have to be perfect.”

Rough diamonds are usually classified as being gem-quality, near-gem or industrial-quality, depending on their color, clarity, size and shape.  According to Rob Bates, a blogger on the diamond and jewelry industries, only "a handful" of companies in the world know how to "economically cut" such large rough diamonds. "But it's always an exciting moment when a mine coughs up a huge stone like that," he said. "It's good for the business, good for the country of Botswana."

Other large diamonds continue to be found in Botswana, including a a recent find by Canadian diamond miner Lucara of a 1,174-carat rough stone from its Karowe diamond mine.  This stone is described as clivage-- lower quality rough that needs to be split before being processed further -- of variable quality with “significant domains” of high-quality white gem material, according to the miner.

Lucara said on the same production day, several other diamonds of similar appearance were recovered from the same circuit—weighing 471 carats, 218 carats, and 159 carats—indicating the large rough was part of a bigger diamond with an estimated weight of more than 2,000 carats. Lucara also found these diamonds in the same production run as the 1,174-carat rough diamond.  Though it cannot be proven beyond doubt, GIA researchers strongly believe that the diamond weighed more than 2,700 carats at one point, as it is thought the 812.77-carat “Constellation” along with a 373-carat rough and 296- and 183-carat chunks all broke off this same stone.

At present, the largest diamond ever recorded is the 3,106-carat Cullinan Diamond, found in South Africa in 1905. The Cullinan was subsequently cut into smaller stones, some of which form part of British royal family's crown jewels.

Role of Technology

As these numbers show, big diamond finds have become more common in the past handful of years. This is due largely to an improvement in the technology behind processing and recovering diamonds, spurred along by a demand for larger stones, industry expert Russell Shor wrote in a 2016 Gems & Gemology article.

Advances, he wrote, include in the initial crushing, “‘kinder, gentler’ methods known as ‘autogenous,’ which tumbles or grinds the kimberlite pieces against one another without the intense pressure generated by crushing,” as well as the use of X-ray processing, which improved the recovery rate and saved large stones before they hit the crushers.

Botswana’s president, Mokgweetsi Masisi, inspects Debswana’s find. Photograph: Monirul Bhuiyan/AFP/Getty Images