Last Summer, the second largest diamond ever discovered was lifted gingerly from the depths of the Karowe mine in Botswana, owned by Canadian firm Lucara Diamond.
Weighing in at 2,492 carats, its colossal size – enough to fill an adult hand – means you would have to go back to 1905 to find a bigger stone. That would be the famous Cullinan, mined in South Africa, and which would eventually make its way (in several parts) to the British Crown Jewels.
The task of keeping such a huge gem in one piece is almost as challenging as unearthing it in the first place. Karowe used an X-ray diamond recovery system, developed by Lucara to preserve large, high-value diamonds and shield them from the ore-crushing process. It was installed after another of the mine’s recent large finds, the Lesedi La Rona, suffered during its journey through the plant’s mill. Counter-intuitively, while diamonds may be extremely hard and difficult to scratch, they can actually break relatively easily.
Placing a value on the as yet unnamed jewel is difficult as its quality and potential for cutting are not yet known. However, in 2016 a diamond half the size, discovered in the same mine, was reported by the BBC to have gone to a London jeweller for $63m. In 2019 an even bigger find (1,758) was snapped up by Louis Vuitton for an undisclosed sum.
Whatever it is about the geology at Karowe, it certainly seems to favour record breaking stones.
When this new diamond was identified, the head of the crew on duty is said to have called the local managing director and yelled “The Eagle Has Landed!!” down the phone. He wasn’t wrong. The Financial Times reported that, on announcement, this single find catapulted the company’s share price upwards by around 40%.
But how useful is a giant diamond?
The most expensive diamond ever sold at auction was the Pink Star in 2017, mined by De Beers in South Africa and sold for $71m. However, it was actually the vivid colour (the clue’s in the name) rather than its size (132 carats in the rough) that influenced the enormous sum.
In truth, mega-diamonds are not that easy to sell. Collectors with suitably deep pockets are few, and rendering such diamonds into smaller, profitable gems is a complex, risky and nerve-wracking business, requiring enormous skill. (The Pink Star took 20 months to cut.)
However, they may have another, more important purpose. So called ‘legacy’ stones that have a story attached to them are good news for a diamond industry that needs to ignite excitement in the market. And it certainly brings welcome attention to Botswana and its diamond industry. So much so that the gem was first presented to the world by Botswanan President Mokgweetsi Masisi. Holding the near half a kilogram stone in his hand, Masisi declared he was overwhelmed, admitting that he felt “lucky to have seen it in my lifetime.”
With good reason, Lucara President and CEO William Lamb also said in a statement: “We are ecstatic about the recovery of this extraordinary 2,492-carat diamond”.
Other giants of the gem world
Largest sapphire: the Star of Adam, an oval-shaped blue star sapphire, weighing 1,404 carats, discovered in Sri Lanka in 2015. Estimated value between $100 and $300m.
Largest emerald: Thought to be the Bahia, mined in Bahia, Brazil in 2001, approximately 1,700,000 carats. (Nearly 350kg). Has enjoyed a chequered ownership history, which at one point saw it seized by the Los Angeles Sheriff’s Department as part of a legal dispute. In November a court ruled that the emerald should be returned to Brazil. Value almost impossible to estimate, but figures as high as $400m have been suggested.
Largest ruby: the Star of Fura; discovered in Mozambique in 2022, and was sold in 2023 for $34.8 million, making it the largest and most expensive ruby ever to be auctioned — 55 carats, twice the size of the previous biggest ruby ever found.
And just for variety, the largest pearl: the Giga Pearl is the biggest certified, non-nacreous pearl in existence. It weighs more then 27kg, is nearly 40cm in length, and is currently showcased within a gold octopus sculpture. Value estimates have ranged up to $200m. It’s actually a family heirloom, passed down across a couple of generations, and originally saw birth within a rare giant clam. As a ‘blister pearl’ it grew along the interior shell of the clam, rather than within its mantle, hence the size.