I had. In September, when I visited Mansori in his office, I was joined by Armstrong and Geoffrey Madderson, of TOMRA, the maker of the XRT scanners. After half an hour of conversation, Mansori retrieved the Sewelô from a safe and dramatically placed it on a mahogany table in front of us.

I was not expecting to be moved by a rock. The diamond was so large that I could not wrap my fingers around it. In most photographs, the color of its rind appears black, but in person it looked more silvery. The stone was cold—at least, until all of us had handled it, after which it felt as warm as a pebble in sunlight. It sometimes sparkled. Its planes were smooth, like marble. I now understood why Ketshidile Tlhomelang had spoken to me about its sensual pleasures. The diamond also prompted unusual thoughts. Because of its dark rind, the stone seemed to carry its prehistoric past with it, in a way that clearer diamonds do not. It was a reminder that the Sewelô was created before the planet’s atmosphere contained oxygen, when the only life-forms were single-celled organisms. In one sense, I realized, diamonds are baubles—somewhat vulgar totems of wealth. In another sense, they are vessels of deep time unlike anything else that can be found near the surface of the earth.

Mansori is a businessman, but he shared some of this sense of wonder. He told me that he was loath to do anything to the Sewelô except look at it. Rough was its pristine state. He wondered whether it might be best for the diamond to sit in a museum vitrine, unpolished. Of course, that would be untenable: Lucara has shareholders. Investors like to realize the value of their assets. Some weeks later, I discovered that, at the very moment I was holding the stone, Mansori and Thomas were engineering a bold plan for the Sewelô.

Earlier this month, Lucara and an entity co-founded by Mansori, HB Company, signed a deal with the luxury-goods giant Louis Vuitton. The Sewelô is now owned jointly: Lucara has a fifty-per-cent stake, the others twenty-five per cent each. None of the parties would confirm exactly what value had been placed on the Sewelô, but one knowledgeable person told me that the price was in the “low millions” of dollars, in part because of the uncertainties about the diamond’s interior. Louis Vuitton will sell the polished gems manufactured from the stone, but, before the Sewelô is cut, it will tour the world, in order to educate people about the geological history of diamonds. Thomas also stipulated that five per cent of Louis Vuitton’s net revenue from the Sewelô be channelled into corporate social-responsibility projects that Lucara runs in Botswana, specifically the funding of a large and well-appointed school that the company is building near Karowe.

The deal is unprecedented. Louis Vuitton’s parent company recently bought Tiffany, but the fashion house has never itself been a serious diamond retailer. Becoming a partner in the Sewelô is designed, in part, to insure that its entrance into the diamond sphere will be noticed. (Louis Vuitton hosted a lavish “launch party” for the Sewelô on January 21st, during Paris Fashion Week.) Lucara and HB, for their part, hope to plunder Louis Vuitton’s exclusive list of rich clients. This is the first time that all three parts of the diamond supply chain—miner, manufacturer, and retailer—have agreed to work on a stone together. No other luxury-goods firms were approached; Thomas made the connection with Louis Vuitton’s chief executive, Michael Burke, over lunch in Florida. There was so much secrecy surrounding the deal that Lucara’s leadership team did not even use the name Louis Vuitton during their internal discussions. Their potential partner was known, instead, as Crocodile.

There was jeopardy in the arrangement, for all parties. Mansori had analyzed the rough diamond using a number of scanners, including an adapted medical machine that normally measures bone density. By December, he still had only a general idea of what lay beneath the Sewelô’s black rind. Mansori believed that there might be as many as two hundred and fifty carats of white, gem-quality diamond within the Sewelô, but he couldn’t be sure until he polished windows and inspected the interior.

“There will be surprises,” Mansori told me. His partner in HB, an Israeli named Shai de-Toledo, said, “This is the most speculative stone in history.”

With this deal, Lucara was once again provoking the traditional diamond business—it was bypassing Antwerp’s brokers. Eira Thomas made no apologies. “There is just no way we’re going to continue to transact diamonds the way we do today,” she told me. “My view is that the whole industry is going to go this direction.” Disruption seems to be the point of the Sewelô deal. Mansori told me recently that he welcomed any brickbats. The deal, he said, “will irritate each and every player in this industry—it takes the playing field and turns it upside down.”

Whatever is within the stone, Lucara and HB believe that they have reëngineered the market, at least for big diamonds. In the past, manufacturers have analyzed rough diamonds, created the best possible polished gems from them, and then attempted to find customers for those jewels. With this new arrangement, that equation was reversed. Wealthy customers will now be able to commission Louis Vuitton to carve a diamond, perhaps of their own design, from the Sewelô. Mansori’s mind raced with possibilities. Maybe they would make three identical jewels for a billionaire’s triplet daughters? Or, perhaps, a horse’s-head diamond for the billionaire owner of a racing stable? Then again, if the client did not demand perfect color and clarity, HB could fashion the world’s largest polished diamond out of the Sewelô—a jewel of a thousand carats.

In September in Antwerp, Mansori sat in his office and watched as his three guests beheld the Sewelô. From the moment the stone came out of the safe, it spent barely thirty seconds out of someone’s grip. We left thumbprints on the diamond’s planes. Mansori, laughing, said, “You see? It will not be put down.”

John Armstrong, the Lucara geologist, became somewhat giddy when he held the diamond. “It has heft,” he said. “Life.”

Finally, Mansori took the Sewelô in his bony hands, and rotated it this way and that. Since receiving the diamond, in the early summer of 2019, he had spent a considerable part of every working day staring at it. Despite his familiarity with the stone, he still seemed fascinated by its complexity. He pointed to where the black rind was thickest, where it abutted more translucent material.

“You feel nature is playing hide-and-seek with you,” Mansori said. He then turned away, for a more private inspection.

“There’s great importance here,” he said, to nobody in particular. “Not value. But storytelling. Is there a regular white stone inside? I don’t know. I don’t think so. There might be significant white pieces inside. Significant. But value is secondary. You need to tell the story right.”

Mansori then became a little lost. He pulled out his iPhone, shone its flashlight into the diamond, and said, “There are moments when you can see right through.” ♦