Time for the science – a guide to lab-grown diamonds

Laura McCreddie-Doak

TAG Heuer grew a pink crown-shaped version, Breitling has sworn to use only these by the end of 2024, meanwhile De Beers has nixed its line using them. We’re talking of course about lab-grown diamonds. Lab-grown stones aren’t new – they’ve been around since the 1940s. The big breakthrough, in terms of their use, came in December 1954, when General Electric (GE) produced the first commercially successful synthetic diamond. Created for manufacturing and tech industries, these stones were as hard as natural diamonds and had the same high levels of conductivity, but because they weren’t made to be seen, they didn’t have quite the same white, flawless appearance.

It took until the 1970s for labs to start experimenting with the possibility of growing stones that look like natural ones. Finally, by the 1980s, procedures had been refined enough for them to produce diamonds that could rival mined stones when it comes to those famous four Cs used to price and select a stone: cut, clarity, colour, and carat.

What’s the difference?

Diamonds made in a laboratory aren’t fake, they are chemically and structurally real. By contrast, the likes of cubic zirconia or moissanite look similar to diamonds but have different chemical and physical properties. You can test this by breathing on one of these gems – it’ll fog up.

The only difference with lab-grown stones is that the intense heat and pressure required to form them is the same, but simulated via two chemical processes rather than happening naturally. Both start with a flat slither of another diamond, known as the seed, then the first option is high pressure high temperature (HPHT), and the other is chemical vapour deposition (CVD). The former places the seed in among pure graphite carbon, and then exposes it to extreme heat – around 1,500ºC – and extreme pressure of approximately 15 million pounds per square inch. For the other option, the seed is placed in a chamber filled with carbon-enriched gas and heating it, which forces the carbon atoms in the gas to stick to the seed; the build-up of which grows the diamond. After this, you get your lab-grown stone.

What are the arguments?

The superior quality of this new breed of lab-grown diamonds means that fine jewellers now have a choice when it comes to the origins of their stones. It’s a choice that, despite there being no visible difference in the two types of stones, has led people to take very firm stances on which type of diamond is better to use – often for strongly personal, ethical reasons.

When lab-grown diamonds started to be used more widely, with some brands setting up to only use these stones, the leading argument was ethical. Mined diamonds were painted as environment-destroying, detrimental to local indigenous communities – just plain evil. Lab-grown were none of those things. A 2019 report, admittedly published by the Natural Diamond Council, claimed that, as many of these labs were in countries that relied on coal or natural gas for energy, the emissions produced were three times higher with a lab-grown stone than with a mined one.

Using something the report called “an average of estimates in the public domain”, it came to the conclusion that, for every polished carat of a mined diamond, 160kg of CO2 was produced, compared to 511kg per carat for lab grown. The Natural Diamond Council also gave examples of places such as Botswana and parts of Northern Canada, where mining company De Beers has worked with the local community, made it more profitable, and improved education and healthcare provisions. Neither argument told the whole story. However, it did start a conversation that acknowledged both sides had ethical grey areas, it wasn’t just “mined = bad, lab-grown = good”; something that led to the creation of labs using green sources of energy, such as the UK-based Skydiamond and US-based, Leonardo DiCaprio-backed Diamond Foundry, and now Ammil in Switzerland.

“Unfortunately, the lab-grown diamond industry has inherited some problematic practices from the traditional diamond industry, which is why we continuously strive to set new benchmarks in transparency and sustainability,” explains Taryn Steinberger, co-founder of Swiss jewellery brand LOEV, who has partnered with Ammil, the first Swiss lab to grow diamonds that uses green power to run its machines. “Our collection uses diamonds grown entirely in the heart of Switzerland, surrounded by our famous mountains, and produced using 100% local, renewable energy.”

What can they be used for?

Environmental concerns aside, the interest in the lab-grown industry has started to move, particularly with regards to watches, away from ethical arguments to something more adventurous. Rather than asking “how can we replicate natural stones?”, brands are now experimenting with the myriad possibilities growing a diamond, rather than cutting and polishing one, offers.

TAG Heuer was the first to explore the answers to this question with its 2022 Carrera Plasma. A love story to carbon in all its forms, it featured diamonds set into the carbon-fibre case in unusual shapes that could only occur outside of nature, and a single diamond grown in the shape of a crown. It has since experimented with colour, including growing pink-diamond crown for a Carrera that has since been immortalised by being worn during Ryan Gosling’s Oscars performance of I’m Just Ken – certainly an upgrade to his pink dial Carrera. Because nothing says “see you on the Malibu beach” more than a man rocking pink diamonds. And this appears to be just the beginning.

“Lab-grown diamonds allow for more creativity in the luxury market at a more reasonable price,” says James Johnson, co-founder of Ammil. “For example, are we currently working on perfectly calibrated diamond bezels with calibrated tapered trapezoid shapes diamonds.” When that sees the light of day Johnson won’t say, but it shows that the watch world is thinking creatively about what lab-grown diamonds can offer beyond a simply adding a little sparkle.