Editor’s Note
This article explores the technological evolution and market impact of lab-grown diamonds, from early HPHT methods to today’s CVD processes, challenging traditional perceptions of value and luxury in the gemstone industry.
For a chemist, diamonds are a three-dimensional cubic lattice of carbon atoms. For most of us, they are the ultimate status symbol. But for how long will they remain so?
In the 1950s, the American giant General Electric was the first to discover the recipe for ‘baking’ a diamond. The “High Pressure High Temperature” (HPHT) method it developed—which recreates the conditions under which natural diamonds form deep within the Earth—is still used today.
A giant steel anvil crushes a fist-sized cylinder of graphite with a force equivalent to the weight of the Eiffel Tower turned upside down. At the same time, the cylinder is baked at temperatures up to 2,000°C. That is enough to make the layers of carbon atoms in the graphite rearrange into a diamond structure.
Diamond is the hardest material in the world, and HPHT remains the best way to produce the millions of tiny stones known as diamond grit, which costs a few dollars and whose abrasive power makes them ideal for tools like files and oil drill bits.
Back then, the world’s largest diamond company, South Africa’s De Beers, quickly realized that this new technology was both a threat and an opportunity and entered the business.
says Steven Coe, head of research at De Beers’ synthetic diamond subsidiary Element 6—named after carbon’s place on the periodic table.
But this technology has a drawback. Tiny amounts of nitrogen from the air infiltrate the diamonds and turn their color to an unattractive murky green. This explains the enthusiasm for a new diamond-making technique: Chemical Vapor Deposition (CVD). Instead of pressurizing graphite, it produces a sheet of diamond using a carbon-containing gas like methane. Although it takes longer—weeks instead of minutes—the crystals are purer and clearer and can be made to the required size and dimensions.
CVD opened the doors to a new world of applications, driving rapid growth in the industry.
At Element 6’s huge new research center on the outskirts of Oxford, England, Steven Coe opens his briefcase to show a surprisingly wide range of objects, many of which don’t even look like diamonds. There’s something that looks and feels like a disc of acrylic or plexiglass. It is a circular window, 12cm in diameter, for high-power lasers.
explains Coe. And because diamond is the best thermal conductor of all known solids at room temperature, the window doesn’t overheat. But an object of this size currently costs $100,000.
This thermal property also enables another unexpected application in the field of electronics. As circuit boards shrink ever smaller, the problem of overheating has arisen. Element 6 is selling large quantities of diamond heat sinks: the circuit system passes over a piece of diamond that absorbs the heat. Gold coated with this diamond sheet provides an electrical contact that does not deteriorate, present in many modern devices.
Another striking object is a scalpel blade, so sharp that Coe warns that blood will start to flow before you feel it has touched you. He then pulls a small dome-shaped object from his briefcase.
he says, explaining, “Diamond is the stiffest material and therefore offers the best possible reproduction of high-frequency sound.”
But there is one product that Element 6 absolutely does not make: gemstones. Cynics might think it’s because its parent company De Beers forbids it, as its mines still supply about a third of the world’s demand for natural diamonds.
Indeed, according to diamond advisor and journalist Chaim Even Zohar in Tel Aviv, one of the main centers of the diamond trade, Element 6 owns patents for technologies that could be used to produce coveted blue and green-tinted gemstones, but does not produce them.
says the expert, who believes the company is only postponing the inevitable.