For centuries, people have gone to great lengths and extraordinary costs - from the baked Namib Desert to the ice-locked Canadian tundra - to pull diamonds out of the Earth, endlessly searching for the dead volcanoes that thrust those transmuted carbon relics from the planet's core and into a special place in our imaginations.

But one no longer has to go so far, or get very dirty, to find diamond. In a bright, well-lit, key-carded clean room not far from San Francisco International Airport, on a non-descript street of low-rise logistics and light-industrial warehouses, a diamond is being created before my eyes. Well, not quite before my eyes - the light would be too intense - but inside a reactor, which doesn't look much different to racks of data-centre equipment, albeit fed by any number of hoses carrying gasses and water.

Diamond Foundry CEO Martin Roscheisen Ian Allen


Behind the edge of a piece of glass, an eerie, spectral blue light spills out. "The kind of glow you see is the optical emission from the actual growth process occurring," says Jeremy Scholz, the tall, baritone-voiced chief technical officer and co-founder of Diamond Foundry, the startup producing what are known as lab-created, or cultivated, diamonds. Prior to starting the reaction, Scholz had turned off computer screens and advised me that mobile phones were not allowed. "As we energise that carbon-containing gas, it lights up just like a fluorescent light does."

The process occurring inside that chamber - the size of a bowling ball, which, with its round, bolted porthole window looks rather like a Jules Verne submarine - is known as chemical vapour deposition, or CVD. In simplest terms, as Scholz describes it, it's the "act of growing a solid material from a gas".

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Inside, a 12mm-thick plate, or "diamond seed", will be exposed to, among other things, hydrogen and gaseous forms of carbon, which are energised by a high-intensity magnetic discharge. This is enough power to send an 18-wheel lorry down the motorway, with temperatures hotter than the Sun. The diamond grows, in a process not vastly dissimilar - in the broadest scientific sense anyway - from the "grow a crystal" kits sold in toy shops.

"They're not synthetic diamonds, like synthetic fibre. They're real diamonds. They're grown diamonds" Martin Roscheisen, CEO of Diamond Foundry


The result of this process - one of Diamond Foundry's rough stones - is placed in front of me on a conference-room table. "They're not synthetic diamonds, like synthetic fibre, where you are talking about a different material than real fibre," says Martin Roscheisen, the company's CEO. "They're real diamonds. They're grown diamonds." Wrinkling his forehead behind translucent eyewear as he listens to a question, I catch a resemblance to the late comedian Robin Williams - by way of Bavaria.

He hands me an eyeglass called a loupe. I take a pair of tweezers and fumble with the rough stone, which feels almost comically unsubstantial in light of its theoretical value. I peer into it through the lens. Eventually, the diamond's light - a bit grainy, a bit yellow-seeming - swims into focus. I am hardly moved - to me it just looks like one of the rocks in my daughter's geology kit. But once this stone is cut and polished - by cutters who previously worked with mined diamonds - achieving its characteristic brilliance, neither I, nor most anyone else, would be able to tell this was man-made.

Roscheisen, a German native with Austrian citizenship, studied computer science and engineering at Stanford University in the 90s, where he was classmates and friends with future Google founders Sergey Brin and Larry Page. He was a serial entrepreneur in a string of unicorns including eGroups, TradingDynamics, and FindLaw before co-founding Nanosolar, the company that brought ultra-thin (some ten times less than conventional technology), affordable solar panels to market.

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While at Nanosolar, Roscheisen hired Scholz, who was working on unmanned helicopters at Boeing. "It was interesting, but I wanted something smaller, more nimble," Scholz says. At Nanosolar, Roscheisen jokes, they coined a term - "Scholz engineering" - after his capabilities in building large, complicated tools.

This grape-free wine is made in a laboratory Start This grape-free wine is made in a laboratory

That company flamed out in 2013, the victim, says Roscheisen, of low-cost Chinese competition and the expensive rigours of reliability testing. Roscheisen and Scholz began searching for a new venture. Much of Nanosolar's work involved chemical vapour deposition to make solar panels. They soon became convinced that the technological breakthroughs they'd made in solar could be brought to diamonds, bringing new levels of speed and industrial efficiency to a cumbersome laboratory process. "There was a big opening in the industry - and we could bring the right skills from all our contacts in the Valley," says Scholz.

In 2013, the newly formed company set to work. For two years, the team toiled under the radar, adjusting the parameters, trying to create a lab-grown diamond with newfound speed, quality and efficiency. They wanted to take the "lab" part out of "lab-grown diamond" and turn it into a manufacturing output. They started with low-hanging fruit such as the brown diamonds used in industrial equipment before working up the chain. One of the first things they did when they grew a diamond was to take it to a jewellery shop and have it evaluated. "He said it was low quality," Scholz remembers. But, most importantly, the jeweller said it was a low-quality diamond.

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Diamond Foundry launched to the public in 2015, attracting investors such as Twitter's former CEO Evan Williams and Leonardo DiCaprio. Roscheisen says the company has to date raised "Under $100 million [£78m]". "It's a truly green production process," says Roscheisen. "We take the two big greenhouse gases - methane and carbon dioxide - and we get diamonds, with oxygen and water as the output."

Diamond Foundry chief technology officer and co-founder Jeremy Scholz Ian Allen

Lab-grown diamonds are nothing new, but Diamond Foundry is betting that improved technology and an evolving mindset about the ethics of mined diamonds have provided a window for disruption. "We are the fastest-growing company in luxury retail," claims Roscheisien. The company's diamonds, he says, are popping up in upmarket stores such as Barneys and retailers like Spence Diamonds, which promises artisan stones that are "as stunning as they are socially responsible".

Are consumers ready for a lab-grown engagement ring? Perhaps. While lab grown diamonds represent less than one per cent of total annual production, there are signs of change: in 2016, Stuller, the largest jewellery manufacturer in the US, joined the International Grown Diamond Association. But the real glittering prizes for Diamond Foundry - this is Silicon Valley, remember - may lie less in eternal love than in Moore's law.

People have long been trying to artificially manufacture diamonds, less for adornment than industry. In 1955, American physical chemist H Tracy Hall created the first artificial stones while working for General Electric's Project Superpressure, using a huge, costly, custom-built press. "My hands began to tremble; my heart beat rapidly," Hall wrote. "My eyes had caught the flashing light from dozens of tiny… crystals."

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As Jeff Glass, a professor in the Department of Electrical and Computer Engineering and Materials Science at Duke University, describes it, the combination of high pressure and high temperature "mimics what happens in the ground. You just squeeze as hard as you can on carbon." With the right technique, and maybe a bit of luck, it re-crystallises as diamond. But it was time-consuming, costly and messy.

A decade later, John C Angus, a researcher at Case Western University, began experimenting with making diamonds using CVD - work that was subsequently refined by labs in the Soviet Union and Japan. In the 80s, Glass joined one of the first university research programmes into making artificial diamonds in the US. "It was really playing catchup," he says, as rumours of artificial diamonds attracted the interest (and funding) of the US government. "Is this really true? We wanted to make sure we didn't get left behind."

From left to right: This rough stone is how Diamond Foundry's manufactured rocks appear when they emerge from the plasma chamber. The cut and polished diamond is finished by professional cutters who previously worked with mined diamonds Vrai and Oro

Here is where the cultural desire for the diamond - driven by a mixture of scarcity, marketing and sheer beauty - happens to coincide with the fact that it is one of the most useful materials on the planet. "Its properties are so spectacular, in such rare combination," says Glass, "that you can envision it being used for dozens of applications that many materials could not address." There is its familiar hardness, which makes it the perfect drill bit, everywhere from operating rooms to tearing up motorways. Its carbon nature gives it an inherent bio-compatibility for uses such as medical implants.

Then there's the diamond semi-conductor. Semiconductor wafers, it turns out, are created by adding silicon seeds to a CVD reactor. Diamond handles heat far better than silicon - ideal as our devices get more powerful - and there are experimental diamond semiconductors that conduct a million times more electricity than silicon.

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"Its properties are so spectacular… that you can envision it being used for dozens of applications that many materials could not address" Jeff Glass, a professor at Duke University

As James Butler, Diamond Foundry's chief scientific officer, says, "It conducts heat five times better than copper, yet it's an electrical insulator." Spend enough time reading about the various uses of diamond in the experimental pipeline, and Neal Stephenson's 1995 book The Diamond Age, in which CVD-like matter compilers pump out diamond with such profligacy that it becomes cheaper than glass, begins to seem prophetic.

But how does CVD actually work? There are a number of ways of unleashing energy on gas, or "excitations of the gas phase," as Glass calls it, to produce diamonds. "The way I describe CVD is that you can make a diamond with a microwave, bulb and welding torch." He says he has made diamond with an acetylene torch.

It is a far from simple process, however. Glass says CVD is "Trying to control a gas-phase reaction such that everything works in concert to allow it to form a solid on a surface" - in this case, the original diamond "seed" (which, once a diamond is grown, is sliced off and reused). One needs an incredibly high-energy density, which can be ferociously volatile. As Scholz describes, if the energy is not carefully managed, "It will just go into eating the walls of the chamber or destroying the diamond you were trying to create." Or, as Roscheisen asks, "How do you get electricity out of a cloud without getting lightning?" Scholz was able to harvest the energy, without the thunder and lightning.

How to evaluate a diamond Weight Calculating a diamond's worth involves consideration of carat weight, which measures mass. Clarity Clarity measures internal defects when viewed under 10x magnification. Colour Colour is graded when compared to a master stone set of diamonds. Cut The cut is measured against a set of guidelines for angles and length ratios.

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The high-energy excitation creates a shower of atoms, which settle on the surface of the existing diamond seed. Rather like a game of Tetris, the falling atoms must line up with the structure of the existing layer. Get the chemistry or the maths wrong, or try to do it too fast, and the atoms will be out of kilter. Sometimes the molecules might drift, dirtying the chamber. You might get a polycrystalline structure (the equivalent of Tetris blocks stacking up in a jumbled fashion).

"You might even grow some graphite or some other form of carbon, like fullerene molecules," Glass says, adding that even a trace amount would "wreck the optical properties". Many early lab-grown examples contained elements that were not found in natural diamonds, things like metallic "inclusions", says Scholz. "These would allow a magnet to pick up your diamond."

The art and science of lab-grown diamonds has progressed to the point "where we can grow a more perfect diamond than you find in nature", says Butler. To the average person, even the average jeweller, the two stones would appear alike (Diamond Foundry laser-etches each of its diamonds so people know it was not mined). The difference, found in the presence of trace impurities from the region in which the diamond was mined, would only be revealed under advanced spectroscopy.

Every natural diamond, Butler points out, is as individual as a snowflake. That makes them perfect for jewellery, but less useful for use as electronic equipment. "If you want to use a diamond device for your iPhone, you'd want to make millions that were identical. If you're mining diamonds, how do you find a million that are all identical?"

Diamond Foundry's finished product. It offers traditional cuts such as Princess and Oval, plus "exclusives" like Bullseye and Dome Jamie Chung

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In the 80s, Butler was posted with a US Navy laboratory, where he soon became involved with the "CVD diamond game", working for influential lab-grown-diamond companies such as Apollo, which later went bankrupt. He joined Diamond Foundry after he became convinced the company was on the verge of "a breakthrough over other technologies that are out there", he says. "But that technology alone would have succeeded if we didn't have the financing, marketing, branding and all the other things that are going on with the company." In other words, what he was saying was the potential successor to silicon, the disruptive diamond, needed a touch of Silicon Valley magic dust.

From his atelier a few blocks from New York City's diamond district, David Alan Wegweiser crafts custom pieces under the name David Alan Jewelry. Diamonds feature significantly in his work. ("They really are my wheelhouse," he says.) He learned his trade as an apprentice, cleaning workbenches and tools. Before starting out on his own, he was creating one-of-a-kind designs for diamond dealers.

One day in the early aughts, a client - "a very high-end sapphire guy" - came to him with a special stone. "It was ten-carat, no heat, a knockout Burma sapphire, which cost $100,000 [£78,000]. We made him a ring." A month later, Wegweiser says, "He came back, to my astonishment, with a matching stone." The client wanted the same ring. Upon further examination, the jewellery designer realised the sapphire was synthetic. The client, he was told, "wants to keep the real one in the safe and wear this one around".

"It takes us two weeks to grow a diamond… but the atoms of our diamonds are as old as the Universe" Martin Roscheisen, CEO of Diamond Foundry

The story hints at the curious nature of precious stones. While the woman was happy to wear the artificial gem in public - because to the untrained eye it was indistinguishable from the mined version - she still wanted the private satisfaction of owning the actual sapphire.

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Diamond producers, of course, have long tried to emphasise the uniqueness ("real is rare" goes a recent advertising slogan) and sheer geologic age of their product. As Paul Zimnisky, a New York City-based diamond-industry analyst, describes it, "The fact that most of these diamonds were formed a billion years ago - it's one of the oldest material things you can own - and that it's a non-renewable resource; in your mind there was some sort of tangible value associated with that."

Roscheisen is familiar with this argument, and has a quick rebuttal. "It takes us two weeks to grow a diamond with our tools," he says. People typically reply "that fast?" he then points out that it takes about the same amount of time, via the underlying physics, to form diamonds in the Earth. "Then they sit in the ground for a billion years," he says, laughing. "The atoms of our diamonds are as old as the Universe."

Diamond Foundry's plasma chamber, where chemical vapour deposition takes place. It's described by employees as "the Sun on Earth" Diamond Foundry

But it raises a question: if one is not promising enduring geologic time and finite uniqueness, what exactly is one promising with lab-grown diamonds? A lower cost? "Our pricing for common diamonds, other than our champion-sized ones, is very competitive," Roscheisen says. "It's generally between seven and ten per cent below what's available online."

Roscheisen adds that, in his company's case, customers are buying directly from the source, without the involvement of middlemen. And Diamond Foundry's production, he notes, is harder to scale up than mining. "Our diamonds," he says, "are rarer than any mined diamond right now."

Mined diamonds, notes Zimnisky, have always been something of a "Veblen good" (after the economist Thorstein Veblen), with a curious relationship between supply and demand. "It takes a certain price to maintain the demand for that product," he explains. To do that, he says, you need to build a brand, such as Tiffany & Co or Harry Winston. Which is exactly what Diamond Foundry is trying to do, via a two-pronged approach. The first is to emphasise that its products are real diamonds - chemically, crystallographically, ontologically - and not simply a high-tech gloss on materials such as cubic zirconia.


The second is to suggest that these are "diamonds 2.0" - all the beauty and brilliance of the archetypal gem, without the worry over environmental degradation, corrupt regimes and exploited labour. This requires a very particular, perhaps novel, kind of customer: one who cares sufficiently about social values and sufficient threshold of a diamond's realness.

Hovering over all this is the spectre of the diamond semiconductor, which turns the value question on its head. "Most of the diamonds on people's fingers would not have any value in a higher-power electronic application," Butler says. I ask Roscheisen if there is a risk - or promise - that increasing efficiencies in production might lead to a commoditisation of diamonds. "If we have a material that makes the iPhone a thousand times faster," he says, "I can guarantee that the material going into the phone will be more valuable than jewellery."

Tom Vanderbilt is a US-based journalist. He wrote about the robot uprising in issue 06.16