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June 24, 2021
Lucara’s Karowe Diamond Mine in Botswana continues to rewrite the record books. On Tuesday, the mining company revealed a 1,174-carat rough diamond, the third-largest in history and the fourth diamond from Botswana to tip the scales at more than 1,000 carats.
The mining company believes the stone is actually the largest fragment from a rough diamond that weighed 2,000-plus carats, but failed to survive the sorting process. Several other similar-color fragments from the main stone weighed 471 carats, 218 carats and 159 carats, for a grand total of 2,022.
The 1,174-carat stone was recovered by Lucara’s MDR (Mega Diamond Recovery) XRT circuit, a system that uses advanced technology to identify 100-carat-plus diamonds. By monitoring the rocky material for X-ray luminescence, atomic density and transparency, the new technology can identify and isolate large diamonds before they go through the destructive crushing process.
In this case, the system was not calibrated to identify a 2,000-plus-carat diamond. Sadly, it got mashed by the primary crusher. Lucara explained that the MDR is positioned after the primary crusher and is the first opportunity for diamond recovery within the circuit.
About the size of a baseball, the 1,174-carat diamond measures 77mm (3.03in) long, 55mm (2.17in) wide and 33mm (1.3in) thick. The gem exhibits variable quality with significant domains of high-quality white gem material, according to Lucara.
The yet-unnamed diamond takes its place at #3 on the list of the largest rough diamonds of all time, unseating the 1,109-carat Lesedi la Rona, which was discovered at the Karowe mine in 2015.
The Karowe mine was also the source of the 1,758-carat Sewelô (#2, 2019) and a 998-carat unnamed stone (#6, 2020). Only a few days ago, we reported on a 1,098-carat, gem-quality rough diamond discovered at Debswana’s Jwaneng mine, also in Botswana. That gem now ranks fifth on the largest diamonds list.
At the top of the list is the 3,106-carat Cullinan Diamond, which was discovered in South Africa in 1905.
Interestingly, after the Cullinan was unearthed, it took the world’s mining companies 110 years to discover another rough diamond weighing more than 1,000 carats. From 2015 to 2021, that feat has been accomplished four times due to the new technology aimed at protecting extremely large diamonds.
Besides the 1,174-carat fragment and its satellite stones, Lucara recovered many other high-quality white gems at the Karowe mine in early June. These stones weighed 148 carats, 90 carats, 88 carats, 86 carats and 67 carats, respectively.
Year to date, Karowe has produced 17 diamonds greater than 100 carats, including 5 diamonds greater than 300 carats.
Credits: Images courtesy of Lucara Diamond Corp.