Lucara Diamond Corp. unveiled last week a 341.9-carat gem-quality rough diamond recovered from its prolific Karowe Mine in Botswana — a mine that owns an impressive track record for producing the world’s largest fine diamonds.



The company described the specimen as a Type IIa diamond with exceptional color and clarity. It will be sold along with two other 100-plus-carat Karowe-sourced diamonds.

Type IIa diamonds are considered the purest of all diamonds because they are composed solely of carbon with virtually no trace elements in the crystal lattice.

A rough diamond will typically lose half its weight during the painstaking cutting-and-polishing process. Although it’s still unclear what the final shape and weight of the 341.9-carat rough will be, we’re confident the results will be museum-quality.

“The recovery of this magnificent stone once again confirms the quality of diamonds contained within the Karowe resource,” Lucara president and CEO William Lamb said in a statement.



Last spring, we reported on 13 huge diamonds produced by the Karowe Mine. All were larger than 100 carats and two were larger than 200 carats. Eight of the 13 were classified as gem quality.



Gems of these sizes are extremely rare in nature, but new techniques employed by mining companies have improved recoveries and reduced breakage of exceptionally large stones.

Lucara announced the rollout of X-ray transmission (XRT) imaging technology that will allow the company to increase the effectiveness of its diamond recovery. Because of a diamond’s unique properties, the machines can be calibrated to extract valuable material using X-ray luminescence, atomic density and transparency. New recovery and XRT stations were scheduled to be integrated into Karowe's main treatment plant by the end of this month.

Images courtesy of Lucara.