Are synthetic diamonds really better for the planet? The answer isn't clear-cut.

Diamonds possess an unmistakable social allure unlike almost any other gemstone. For many, their ancient provenance and everyday invulnerability symbolizes the lasting strength of a loving relationship. It wasn’t always that way; in the late 1940s, an advertising agency working for the De Beers Diamond Consortium came up with that paradigm-shifting slogan: “A Diamond Is Forever,” an almost immutable geologic ambassador for all sorts of romance and companionship.

Over the last couple of decades, however, a new competitor has risen to challenge the dominance of mined diamonds: synthetic diamonds.

In many ways, synthetic (or lab-grown) diamonds are the same as those extracted from ground: Both are prisms of carbon, tightly bound together to form that extremely tough, rather shiny gem. But instead of crystallizing deep within the planet’s fiery depths billions of years ago, these gems are grown in a laboratory using modern alchemy. And these lab-grown diamonds aren’t just cheaper per carat than their natural equivalents; they are also touted as both more socially ethical and more environmentally friendly.

Counterclaims have been made, particularly by companies focused on selling mined diamonds that suggest their industry brings more socioeconomic benefits. And according to the International Gem Society—citing a 2019 report for the Natural Diamond Council (formerly the Diamond Producers Association)—the producing one polished carat of lab-grown diamond releases three times as many greenhouse gases than the mined diamond equivalent.

So are lab-grown diamonds better for people, and the planet, than mined diamonds? Or is this scientific sorcery too good to be true? For the time being, the answer seems to depend on which aspect you care about most.

“On the environmental side, there’s no question that the lab-grown diamonds come out better,” says Saleem Ali, an energy and environmental expert at the University of Delaware. “But the social side cannot be decoupled. That’s where mining has an advantage.”

Diamonds, mined or grown

Diamonds are minerals like any other, which mean they likely crystallize out of a molten mass of super-hot, carbon-rich soup deep in the earth’s mantle.  They are often several billions of years old too, meaning many were cooked up in Earth’s geologic adolescence.

The mantle and the crust’s underbelly are thought to be jam-packed with diamonds. But vanishingly few have made it to the surface. Those that have can be found in kimberlites: pipe-shaped volcanic formations created by violent eruptions that mostly occurred hundreds of million years ago.

Retrieving these gems usually involves open-pit or underground mining. But some diamonds are also retrieved from riverbeds whose streams eroded kimberlite deposits upstream, while others are extracted from the seabed.

There are two main ways to create lab-grown diamonds. The first is through chemical vapor deposition (CVD). Here, a tiny diamond ‘seed’ is exposed to carbon-rich gas at extremely high temperatures; the carbon particles then adhere to the seed, which then grows into a full-grown gem in a few weeks.

The second method is high pressure, high temperature (HPHT): here, another carbon ‘seed’ (usually another tiny diamond) is put under both immense pressures and temperatures, which causes the seed to crystallize and grow into a larger diamond. And in both cases, these diamonds are cut and polished much like their mined equivalents.

The genuine article?

Although mined diamond-centric companies can refer to lab-grown diamonds as hastily produced and commonplace items without any enduring value, the reality is far fuzzier.

To people determined to have diamonds with a primeval provenance, mined diamonds will always be preferred. And geologists will always opt for mined diamonds, in part because these near-indestructible jewels contain chemical clues about Earth’s earliest history. “The inclusions in them are extremely attractive,” says Thomas Stachel, a diamond geologist at the University of Alberta.

But, despite being made of near-pure carbon, and despite being as tough and lustrous as natural diamonds, lab-grown diamonds have some idiosyncrasies: the chemical fingerprints of synthetic diamonds can differ from natural diamonds depending on the source of carbon used to make them, for example—and experts with the right tools can detect these subtle differences.

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“Is that anything an end-user has to worry about? Of course not. You would never know about it,” says Stachel. “From a crystal structure perspective, they are diamonds—they are absolutely perfect diamonds.”

Is a “real” diamond defined by its origins, or its atomic structure? Lab-grown diamond companies prefer the latter. Ultimately, what makes a diamond—and one worth buying—is somewhat subjective. “It’s really a matter of what the market perceives,” says Stachel.

And if the market has sustainability concerns top of their mind? Lab-grown diamonds are hard to beat.

The battle of the gemstones

A recent report looking into the environmental impact of mined diamonds by Gbemi Oluleye, a researcher at the Centre for Environmental Policy at Imperial College London, makes that clear. Impacts vary in extent and severity from mine to mine, and if renewable energy is used to power certain processes, and water used during mining work is recycled, their deleterious environmental footprints can shrink somewhat.

But mining problems remain myriad. The draining of lakes and destruction of streams, and the leaking of pollutants into them, can irreversibly damage water ecosystems. The often-vast mines themselves eat up huge swaths of forests and fields, which can devastate land-based wildlife.

Open-pit mines can often become contamination-packed landfills when they close. Hazardous and sometimes carcinogenic dust and gas from mining activities can not only harm animals, but the workers in the mines. And the diesel used by trucks and other mining equipment pump out plentiful greenhouse gases.

“It is a lot,” says Oluleye. And just going on greenhouse gases alone, she suspects that mined diamonds—despite industry claims to the contrary—are losing this battle. Olueye calculates that mined diamonds, on average, use 350 pounds of CO₂ per carat. Lab-grown diamonds in the European Union, she notes, can use just 45 pounds of CO₂ per carat; that value is similarly low in China.

Some synthetic diamond companies aim to be exclusively powered by renewable energy, while others opt for carbon offsets—both of which mean the lab-grown carbon footprint can be reduced to single digits or perhaps even pushed into a negative value.

The social caveat

It’s worth noting that, just as it can sometimes be difficult to extract this sort of data from not-always-transparent mined diamond companies, some lab-grown diamond companies and their sellers have occasionally refused to divulge information about their processes or carbon footprints, telling reporters that they either don’t have the figures or can’t reveal information for proprietary reasons.

The socioeconomic side of diamond creation and extraction also cannot be ignored. “Mining creates far more jobs,” says Ali. It has been suggested (not unreasonably) that diamond mining has transformed the overall economies of kimberlite-dense nations, including Botswana. The lab-grown diamond industry is on the ascent, creating more jobs as it rises; but some argue that the mining industry will always be more labor-intensive.

In this sense, lab-grown diamonds “will never compete with mined diamonds,” says Ali.

But that’s hardly the end of the debate. Country-wide economic benefits from mined diamonds are great—unless they finance a “corrupt elite, and everything goes sideways,” notes Stachel. Indeed, the story of the mined diamond industry has its share of dark chapters. Most infamously, mined diamonds have been sold by armed groups, particularly in central and western Africa, to fund acts of war, insurrection, organized crime, terrorism, and oppression.

The Kimberley Process, an international framework created in 2003, has added some much-needed rigor and transparency to the diamond supply chain, making it harder for conflict diamonds (sometimes referred to as ‘blood diamonds’) to be sold.

Although few claim it’s a perfect system, some see the Kimberley Process as deeply flawed; it can be still be remarkably difficult, sometimes impossible, to know if a mined diamond bought from an otherwise legitimate seller is truly conflict-free. And in the last two years, a new and complex wrinkle in this regard has emerged: just a few months after Russia invaded Ukraine, it was reported that Russian diamonds were still pouring into the global supply chain—something that may make diamond-seeking customers uncomfortable.

Conversely, if you know the lab that’s growing your diamond, you can effectively guarantee it is ethically sound.

In short: arguing that mined diamonds are better for people, on a socioeconomic level, isn’t impossible—but it can be troublesome argument to make. And on the sustainability side, it’s more of a slam dunk for the relatively new upstart. “On the environmental side, at the moment, lab-grown diamonds are winning,” says Oluleye.