The Cullinan

In 1905, at a South African diamond mine, workers found a shiny object reflecting the rays of the setting sun. The mine manager was summoned, and he prised out the shiny object with his pocketknife.

It turned out to be the largest gem-quality rough diamond ever found, weighing in at 3,106.75 carats (621.35 g). The Cullinan Diamond, as it became known, also happens to be one of the cleanest large diamonds ever found. A geologist who examined it in 1905 called it “the purest of all the very big stones.” Blue-white, it contains a small air pocket that reflected light like a kaleidoscope.

Such a large diamond presents both a risk and opportunity. Partly due to its immense value, the Cullinan remained unsold two years after its discovery. Eventually, it was sold to the government of colonial South Africa to be presented to the British monarch, Edward VII. The Cullinan was later carved into more than a thousand carats’ worth of cut gems. The two largest diamonds cut from the rough Cullinan now adorn the Crown Jewels of the United Kingdom.

The largest gem cut from the Cullinan, or Great Star of Africa, mounted in the British Royal Scepter
The Diamond Market

People have been trading diamonds for more than two millennia. From at least the third century BC, Indian merchants bought and sold diamonds that washed up in riverbeds, most likely as tools for cutting other gems. By the fifteenth century, diamonds from India had made their way to the markets of Venice and other European cities.

In 1866, diamonds were discovered in Kimberley, South Africa, sparking the world’s first diamond rush. Two decades later, the De Beers consortium was founded, which came to regulate the supply of rough stones, the manufacture of polished ones, and the marketplace itself.

By themselves, diamonds are not all that scarce. Millions of carats of diamonds are mined every year – a massive amount compared to other gemstones. Top-quality diamonds aren’t even the most expensive gems per carat – that honour goes to the fabled ‘pigeon’s blood’ rubies from Myanmar.

Despite that, large gem-quality diamonds are vanishingly rare. When such stones to turn up, they create a lot of buzz. These stones are normally bought at tenders: invitation-only auctions, where clients are invited to view the stone and then decide how much to bid.

Then comes the process of cutting. A skilled cutter can bring out the stone’s internal fire and hide any flaws it may have, while preserving its weight. However, significant financial risks are taken on when purchasing a large stone, as few diamantaires have sufficient experience to consider buying and polishing a big stone. Some of these cutting experts work directly for the most prestigious retailers: Graff, Chopard, Tiffany, and so on. Other buyers act as intermediaries with small rare-diamond firms.

Lesedi La Rona

In 2015, 110 years after the discovery of the Cullinan, another near-pristine white diamond was found in nearby Botswana. Weighing in at 1,111 carats (222.2 g), the diamond was named Lesedi La Rona – “Our Light” in the Tswana language.

Lesedi La Rona

The firm who mined the diamond, Lucara Diamond Corp is a relative newcomer to the industry. Lucara was founded in 2007 by Eira Thomas and Catherine McLeod-Seltzer, together with the Swedish-Canadian mining billionaire Lukas Lundin, who serves as the firm’s chairman. Thomas and McLeod-Seltzer are women who are thriving in a male-dominated sector – and they did things differently.

Thomas made her initial fortune prospecting for diamonds in Canada. But Thomas was eyeing a much bigger prize – rumours of rich veins in Botswana tempted her to set up a mine there.

Lucara’s first mine was near a site called Karowe, which was prospected by De Beers in the 1970s but never developed, concluding that it would cost too much money to extract too few diamonds. When Lucara’s team examined samples that had been extracted in the seventies, they noticed evidence that many diamonds had been damaged in the sampling process, and that De Beers’ statistical models had discounted these larger, broken stones.

Lucara’s geologists realised that the diamonds at Karowe were beautiful and clear, but irregularly shaped. These present challenges to discovery. Therefore, Lucara had to adopt new diamond detection techniques. The technology they eventually adopted was X-ray transmission technology, or XRT. XRT works like an airport luggage scanner, but instead of scanning for shapes, it scans for the characteristic atomic signature of diamonds.

A year after the XRT machines were installed, they found Lesedi La Rona.

Lessons from Selling Rocks

Traditionally, a mining firm tenders its rough diamonds and walks away with a check. But Lucara has been loath to sell its largest stones in this way.

In 2016, Lucara instructed Sotheby’s in London to sell Lesedi La Rona at an open auction. Jewelry from houses like Cartier or Harry Winston are often sold at auction, but nobody had ever sold a large rough diamond that way. Lucara wanted to see if there was a broader audience for a stone that was “a piece of art,” not to mention the first diamond of more than a thousand carats discovered in a century. Unwilling to limit themselves to the traditional diamantaire market, the firm imagined a wealthy private collector buying a rough diamond and keeping it as an investment, or as an objet d’art.

Though the Lesedi La Rona failed to meet its reserve price, it was eventually sold to Graff for US$53 million. Graff has since polished the stone into various extraordinary jewels, including a D-color 302 carat emerald-cut diamond.

Lucara’s management team decided to take the botched auction as an occasion to learn something new. In 2017, Lucara launched Clara, a secure, digital sales platform that uses proprietary analytics together with cloud and blockchain technologies to modernise the existing diamond supply chain. The platform works on the basis that every diamond has a unique shape and color, which means that it is possible to create a digital signature for each stone, and to detail its provenance. If successful, Clara will pose a threat to the old diamond world, because suppliers can reach buyers without an intermediary.


The Karowe mine didn’t stop at producing one treasure. In 2019, another particularly massive diamond was found. When Lucara held a competition to name the gem, 22,000 Botswanans submitted entries. Eventually, the name “Sewelo”, which means “rare find” in the Tswana language, was settled upon.

At 1,758 carats (351.6 g), Sewelo is the largest diamond found since the Cullinan. After the Lesedi La Rona debacle, Lucara had learned not to go for open auction and ‘burn’ the stone by showing it to too many people. But it also didn’t want to go via the traditional diamond dealerships of Antwerp.

The Sewelo Diamond

Sewelo is an unusual stone, principally because it is enveloped in black carbon due to its age – it formed an estimated 2.5 billion years ago. Grading it becomes tricky, but Lucara has examined the diamond through a tiny window in the dark covering and scanned it with lasers. It describes the stone as “near gem quality,” with “domains of high-quality white gem.”

Not Your Regular Customer

Lucara then engineered the sale of the stone to a very unusual, non-traditional customer: Louis Vuitton. Better known for its logo-bedecked leather goods, Louis Vuitton is a newcomer to the rarefied world of diamonds.

However, luxury behemoth LVMH (parent company of Louis Vuitton) has also just completed a US$16.2 billion acquisition of jeweler Tiffany & Co – one of the world’s foremost diamond retailers. Together with the purchase of the Sewelo, LVMH is signalling a serious intent to compete in the high jewelry market.

Aside from raw monetary value, Louis Vuitton is buying into something more intangible: the mystique and romance of diamonds, as well as the associated bragging rights. Though the price Louis Vuitton paid is undisclosed, it is estimated to be well north of US$50 million. Furthermore, Lucara also stipulated that 5 percent of Louis Vuitton’s net revenue from the Sewelo be channelled into corporate social-responsibility projects in Botswana, specifically the funding of a school that the company is building near Karowe.

Though much of the diamond industry remains opaque, it too is experiencing disruption. Concerns over ‘blood diamonds’ and questionable sourcing has led to the greater adoption of lab-grown diamonds, especially among younger customers. For now, Lucara and Louis Vuitton are examples of newcomers that are shaking up the norms of the industry. Will this be enough to rattle the old guard? It’s too soon to tell, but one thing’s for certain: a diamond may be forever, but the industry – not so much.


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