Thursday 12th December 2019

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This diamond’s huge, but is it worth much?

by Greg Klein | April 25, 2019

Thanks partly to new processing gear that’s less likely to break up the stones, Lucara Diamond TSX:LUC keeps pulling record-setting rocks out of its Karowe mine in Botswana. Now the company might have beat its previous record with a 1,758-carat diamond that would be the second-largest of gem quality ever found—if it’s of gem quality.

This diamond’s huge, but is it gem quality?

“Domains of high-quality white gem” may lurk within
Karowe’s largest recovered rock. (Photo: Lucara Diamond)

It’s “been characterized as near gem of variable quality, including domains of high-quality white gem,” Lucara explains. “Further detailed analysis is ongoing.”

The all-time record for gem-quality rough remains the 3,106-carat Cullinan, a 1905 discovery in South Africa that was cut and polished into the 530.2-carat Great Star of Africa in Queen Elizabeth II’s sceptre and produced eight other gems for Britain’s Crown Jewels. Tentatively holding second place is Lucara’s 1,109-carat Lesedi La Rona, which earlier this month hit the market as a 302.37-carat jewel with 66 smaller stones.

The company expects further fantastic finds, thanks to an x-ray transmission (XRT) recovery circuit commissioned in 2015 that strives to keep large stones intact. Since then Lucara produced 12 diamonds surpassing 300 carats, with the new find and the Lesedi La Rona exceeding 1,000 carats, out of total production approximating 1.4 million carats. Half of the 12 300-plus-carat rocks were gem quality, Lucara stated.

XRT notwithstanding, recovery might have separated Lesedi La Rona from a stone originally weighing in at 2,774 carats. That possibility was reported by the Gemological Institute of America last year after analysis of the 1,109-carat piece, a 373.72-carat fragment that Lucara sold separately, the 812-carat Constellation and three others weighing 374, 296 and 183 carats. The GIA’s analysis found “compelling evidence” that all five “likely originated from the same rough, with a combined weight of at least 2,774 carats.” Geological as well as recovery processes could be blamed for the break-up, Lucara responded at the time.

But the source of those recoveries should improve too “as we mine deeper in the ore body and gain access to the geologically favourable EM/PK(S) unit, the source of both of our record-breaking, plus-1,000-carat diamonds,” said CEO Eira Thomas.

See an infographic: Six of the world’s most famous diamonds.

Read about Koh-i-Noor: The History of the World’s Most Infamous Diamond.

Read Resource Clips visits the diamond industry in Belgium and the Netherlands.

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