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Karowe, a state-of-the-art diamond mine in Botswana owned by Canada-headquartered Lucara Diamonds with a proven knack of yielding oversize stones, has done it again. According to the company, a 1,758-carat diamond has recently been discovered at the mine, taking the title of the world’s second largest stone away from the 1,109-carat Lesedi La Rona, which was discovered at the same site in 2015.

According to a statement released by Lucara, the recently mined stone weighs almost 352 grams, and measures 83 millimeters by 62 millimeters by 46 millimeters. But unlike the high-quality Lesedi La Rona, the stone is described as a diamond as “near gem of variable quality, including domains of high-quality white gem.”

The massive stone, which is said to be the size of a tennis ball, does still not measure up to the rough diamond that has held the world record for more than a century. That is the 3,016.75-carat Cullinan Diamond, which was discovered in South Africa in 1905.


The open-pit Karowe, which means precious stone in the local Twana language, was commissioned during the second quarter of 2012. It has thus far produced 2.4 million carats. About 180 of them have sold for more than $1 million and 10 have sold for $10 million and more.

Lucara attributes some of its success at Karowe to its use of X-Ray Transmission (XRT) sorting technology, which allows diamonds to be recognized and separated based on their specific atomic density, regardless of how thick they are. 

The system played a key role at Karowe in the discovery of the Lesedi La Rona and, earlier, the uncovering of the 813-carat Constellation Diamond. Just last year, the technology helped the mine locate a 472-carat stone and a 327-carat diamond.

The 1,758-carat rough diamond discovered at Karowe, now considered to be the world’s second largest stone ever mined entact.

The open-pit of Lucara’s Karowe mine in Botswana, site of the some the largest-ever rough diamonds discovered. 

“Lucara’s technologically advanced, XRT diamond recovery circuit has once again delivered historic results,” said Eira Thomas, Lucara’s CEO. “Karowe has now produced two diamonds greater than 1,000 carats in just four years, affirming the coarse nature of the resource and the likelihood of recovering additional, large, high quality diamonds in the future, particularly as we mine deeper in the orebody.”


Karowe is not the only mine producing exceptionally large diamonds. Earlier in April, Firestone Diamonds announced it has recovered a “monster of a diamond” at the Liqhobong Mine in Lesotho. In a statement released by the company, it said it had recovered a 72-carat yellow diamond, together with a 22-carat makeable white stone and an 11-carat fancy light-pink stone. The diamonds are scheduled to be tendered in May 2019.

Earlier this month, the Russian diamond-mining company Alrosa said it had discovered a yellow rough diamond weighing 118.91 carats at a deposit in the northeastern region of Yakutia. A similar 109.61-carat yellow diamond was extracted at the site in the summer of 2017.

Ultimately, however, the question how rough a diamond, or the collective value of the host of diamonds extracted from the massive rough stone will be the most important factor, and from the outside the evidence is not particularly promising. 

The 1,109-carat Lesedi La Rona is another story. It was discovered in November 2015, and sold in 2017 for $53 million to the British jeweler and diamond dealer Lawrence Graff. It has yielded 67 polished diamonds, including the 302.37-carat Graff Lesedi La Rona, which has been described the largest square emerald-cut diamond in the world, a 11.12-carat D-flawless oval-cut stone and a 6.06-carat D flawless cushion cut gem.