Uncut gems: are they worth the gamble?

While William Caxton was setting up his printing press in London, Lodewyk van Bercken of Antwerp was cutting the city’s first major diamond, a whopper of 137 carats for the bling-loving Duke of Burgundy, Charles the Bold. Bercken was using a polishing tool of his own invention, the scaif. Still used today, it revolutionised the manufacture of stones, maximising refraction and igniting the inner fire that burns within each one.

More than 500 years later, I am accompanying Jody Wainwright, sixth-generation scion of the dynasty that owns British jeweller Boodles, on a diamond-buying trip to Antwerp — a rare chance to buy gems during a 10-day tender. As we walk through the historic centre of Antwerp to the diamond bourse, I cannot rid my mind of Dame Shirley Bassey bawling out “diamonds are forevaaaah”. I can already imagine myself before mounds of scintillating stones, grasping great handfuls and then letting them trickle through my fingers in a shower of shimmering light and limitless value.

We arrive at the fabled Diamantclub van Antwerpen, the heart of the Flemish diamond trade since the late 19th century — but all I can see is a slab-sided structure of concrete and glass that appears to have been designed by an architect chiefly known for multistorey car parks. La Bassey stops warbling, and those rivers of light streaming through my fingers dry up. Apparently, King Baudouin of the Belgians opened this unprepossessing building in 1969 — to which I can only answer that King Charles III of England would surely have it bulldozed.

I imagine letting great handfuls of them trickle through my fingers

In coming to the Diamantclub, Wainwright — a man who, beneath his calm navy-blue suit and printed silk tie, is wildly passionate about compressed carbon — and I are going further down the supply chain than most jewellers venture. “Most brands buy polished stones from the manufacturers,” says Charles Bonas, the man we’ve come to meet once we’ve had our passports checked, been through security doors and passed through what looks like the assembly hall of a secondary school (actually it’s an empty trading floor). Beyond that is the fortified door of Bonas Group — a service provider for “junior mines” everywhere from Africa to Canada.

Charles Bonas is a fifth-generation trader. “The mines send us their run of mine” — diamond-speak for what has been dug up recently — “we sort it, value it, sell it, collect the money, and pay the miners,” he explains. For the auction, the goods (more diamond jargon) arrive in Antwerp in the rough where they are “deep boiled”, a chemical cleaning process, before being sorted into what look like around 90 piles of gravel, albeit gravel worth in excess of $25mn. On the day I visit, the sorting of the run of mine will be from the Renard in Québec. The 200,000 carats are sorted into “parcels” in piles that begin with the low-value, industrial-quality stones. These diminish in size as they increase in value until the parcels comprise single stones above eight carats. It is to these that Wainwright gravitates, whipping out his loupe to inspect individual stones, estimating the carat weight once the rough is “opened” and identifying which might make a round cut, which a pear, which an emerald, and so on.

For a “small, nimble luxury brand” like Boodles, this tender is an ideal opportunity, says Bonas. He says it’s not “wrong” that big brands focus on getting polished stones and making “incredible jewellery”. “The difference is that Jody physically comes and looks at stones in the rough. Others simply don’t have the time to do such a thing.”

From the mine to your hand

Rough stones bring romance to what could seem an arid and commoditised approach within the industry, with gems normally priced and sold according to weight, colour, cut and clarity. And Boodles — which has been visiting Antwerp for many years — is not the only one betting on them. Chopard began a few years ago with the 342-carat Queen of Kalahari — which was eventually cut into 23 stones, five of which were more than 20 carats. Caroline Scheufele, Chopard’s co-president and artistic director, says that she has become “keen to source some extraordinary and unique rough stones. It has been an amazing and new adventure.”

Scheufele says that such sourcing has two advantages. “First, the traceability of the stone directly to its mine. We can follow and guarantee the journey of the stone from the mine to the end customer, which is an important aspect for outstanding stones in terms of quality and size.” Second, it’s a chance to exercise a new level of creativity as a jeweller: “It is fascinating to reveal the true beauty and potential of a rough stone to the world.” Early last year, Chopard presented the “Insofu”, a rough emerald gemstone discovered in a mine in Zambia. “It is one of the most important ever found in terms of both weight [6,225 carats] and quality,” says Scheufele. “Remarkable jewels will be cut from it.”

Graff — another family-owned business — is also known for its work with rough stones. In 2019 it “transformed” the 1,109-carat Lesedi La Rona diamond, which was unearthed at the Lucara Karowe mine in Botswana. “For more than 18 months, the stone was meticulously studied, scanned and then expertly cut and polished,” says François Graff, CEO of the company. Upon completion, the 302.37-carat Graff Lesedi La Rona became the largest square-emerald-cut diamond in existence; it also furnished 66 satellite diamonds, ranging in size from less than one carat to more than 26 carats. “Our clients who have purchased these stones own a piece of diamond history,” says Graff.

Wainwright is not looking at stones anywhere near that size; even so, when you are on a shopping trip that might cost you half a million quid, you need to rely on more than just your own appraisal — however experienced your eye might be. Back in the Diamantclub, Wainwright meets Nick Crouch, Boodles’s secret weapon — or “rough diamond valuator and technical specialist”. He has been looking at rough diamonds, first as a sorter and later as a cutter and polisher, for the past four decades. Today, he is examining large octahedral stones from the Gahcho Kué mine in Canada’s Northwest Territories.

To see him at work is mesmerising: he sorts through what look like bits of gravel to my eye, returning most to the little jars in which they have arrived and setting aside maybe one or two that he will inspect further, scanning them with the portable gemological equivalent of an MRI. Once the image appears on his computer, he begins to plot shapes inside the stone to give an idea of what it will yield once it is manufactured. It is upon this basis that he will make an offer in the tender.

The same quiet drama is played out many times over the 10 days or so of the tender period. This isn’t an auction as one normally imagines it: all the bids are sealed and there’s no gavel. Experts — mainly from manufacturers who will in turn supply jewellers, whose identity is kept secret — fly in from all over the world to play their cards in a multi‑dimensional game of poker, with no guide pricing and no idea of whom they might be bidding against.

“They have to make their own judgment,” explains Bonas. “They don’t know what our guide price is. And you can see, especially on large stones, very big differences between different bidders. That’s absolutely normal. It’s a rough material, it’s not a finished product. With polished diamonds it’s clear, it’s got a certificate. All the unknowns are known. But in the rough, people can vary in opinion on what the colour, or the clarity, or the yield will be. So you get these differences — and that’s fascinating.”

“If we’re successful at this tender,” says Wainwright, “I will get on to four or five of our top salespeople and say that from this, say, 20-carat rough, we are expecting such and such a shaped diamond, and I’m thinking about your customer, Mr B, or C.” The customer then can follow the entire process from the rough to the finished piece of jewellery. Each stone is accompanied by a book that is more than just a certificate of colour, clarity, size and reassurance that the stone has been ethically sourced; it is a narrative to which the customer has been a witness or even participated in. “We have had a customer who wanted to do some of the polishing, so the book had a photo of him polishing that diamond.”

Wainwright, so you know, was successful at the tender. Not every rough diamond, purchased, cut, polished, set and sold by his family will tell a story as colourful as that of Charles the Bold, Duke of Burgundy, five and a half centuries ago, but each story will be as individual as the diamond at its centre. “You never know what is going to come out of the ground,” Bonas reminds me. “It’s not a widget. It’s magic.”