The 998-carat unbroken white diamond, measuring 67x49x 45mm is one of the five largest stones ever mined. It won’t remain as such — Lucara said the diamond was clivage, meaning it would have to be split before further processing into polished gems.

“Lucara is extremely pleased with the continued recovery of large high quality diamonds from the South Lobe of the Karowe mine,” chief executive Eira Thomas said in a media statement.

“To recover two +500 carat diamonds in 10 months along with the many other high-quality diamonds across all the size ranges is a testament to the unique aspect of the resource at Karowe.”

Proven record
The mine, which began commercial operations in 2012, has produced 31 diamonds greater than 100 carats, including 10 diamonds greater than 200 carats so far this year.

Before Lucara found Sewelô, the previous holder of the world’s second-largest diamond was the 1,111-carat “Lesedi La Rona”, also dug up by the Vancouver-based miner, in 2016. The rock sold for $53 million to luxury jeweller Graff Diamonds in 2017.

The only larger diamond ever unearthed was the 3,106-carat Cullinan Diamond, discovered in South Africa in 1905. The Cullinan was later cut into smaller stones, some of which now form part of British royal family’s crown jewels.

The ongoing finds have prompted Lucara to move forward with an underground expansion at Karowe, which is expected to extend the mine’s life for 20 years — until 2040.