For the second time this month, Lucara has unearthed a massive top-quality diamond at its Karowe Mine in Botswana.

A few weeks ago, the mining company revealed a stunning 1,080-carat oblong gem that rates as the sixth-largest ever unearthed. On Monday, Lucara unveiled a 692.3-carat Type IIa high white gem from the same source. That diamond, yet to be named, takes its place at #20 on Wikipedia’s “List of the Largest Rough Diamonds.”

Of the top 20 diamonds ever discovered, seven have come from the Karowe Mine. The largest Karowe finds include the 1,758-carat Sewelô (2019), 1,174-carat unnamed (2021), 1,109-carat Lesedi La Rona (2015) and the 998-carat unnamed (2020).

About the width of a golf ball, the newest find was recovered from the direct milling of ore sourced from the EM/PK(S) unit of the South Lobe at Karowe — the same extraction point as the 1,000-carat-plus diamond introduced earlier in August.

The 692.3-carat diamond measures 46.5mm (1.83 in) by 40.7mm (1.60 in) by 28.4mm (1.11 in). Its Type IIa classification represents a colorless diamond with no measurable impurities. Type IIa gems account for less than 2% of all natural diamonds.

So far this year, Karowe has produced four diamonds larger than 300 carats and 20 larger than 100 carats.

Lucara’s MDR (Mega Diamond Recovery) XRT circuit 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.

“The successful track record of delivering some of the world’s largest diamonds continues with the recent recovery of a 692.3-carat diamond,” said Lucara CEO William Lamb. “The recovery of large diamonds from the EM/PK(S) lithology of the South Lobe strongly supports our expectations for the underground project where the majority of material mined will constitute this phase of kimberlite during the first years of underground production.”

The Karowe Mine, which was opened in 2012, had been expected to cease operations in 2025, but an underground expansion at the cost of $683 million promises to extend its productive lifespan until at least 2040.

Credit: Image courtesy of Lucara Diamond Corp.