Technological progress in the production of lab-grown diamonds keeps improving, while technological progress in production of natural diamonds does not. Javid Lakha provides an overview of both the history of lab-grown diamonds and the implications for everything from jewelry to industrial cutting equipment in “Lab-Grown Diamonds” (Works in Progress, Issue 16, August 30, 2024). Here, I’ll just let Lakha tell the origin story of lab-grown diamonds.
In 1950, the General Electric Research Laboratory in Schenectady, New York, assembled a consortium of chemists, physicists, and engineers to form Project Superpressure, an effort to synthesize diamonds in the lab. … To support its research, General Electric commissioned a hydraulic press that cost $125,000, stood two storeys high, and was capable of pressing 1,000 tons. Four years of intense experimentation followed, during which Project Superpressure exhausted all of its original research budget and two additional funding allocations. On the third occasion that the project manager asked for more money, General Electric’s research managers, having seen no tangible results and skeptical of future success, almost unanimously voted to discontinue their support. Guy Suits, General Electric’s director of research, overruled them and approved the funds. …
On 16 December 1954 chemist and Project Superpressure team member Howard Tracy Hall placed two diamond seed crystals into a graphite tube with iron sulfide, capped with tantalum disks. The tube’s graphite would act both as a carbon source and, when electric current was applied to the tantalum disks, a resistance heater. He then placed this cylindrical device into a pressure chamber of his own design. Hall’s pressure chamber, now known as a belt press, consisted of two opposing tapered anvils that compressed the reaction cell from above and below, with the sides supported by prestressed steel bands.
Hall describes how when he envisioned this device, his colleagues ‘felt negatively about it’. His proposal to build a prototype, which would have cost General Electric less than $1,000, was rejected and he was refused time in the machine shop to build it. ‘I fretted about this for a time’, he wrote, ‘and then decided on a sub-rosa solution. Friends in the machine shop agreed to build the Belt, unofficially, on slack time. This took several months. Ordinarily, it would have taken only a week.’
A practicing Mormon, whose church and large family left him little time to socialize with his colleagues, Hall attributed the refusal to build his design and other slights to religious prejudice. When his prototype belt apparatus proved capable of attaining high pressures and high temperatures, Hall requested that its critical components be reconstructed in carboloy (cobalt-cemented tungsten carbide). Once again, his request was refused and it was not until his former supervisor intervened that he obtained permission to buy the carbide components.
To further compound Hall’s sense of injustice, demand for Project Superpressure’s thousand-ton press was so high that Hall’s improved pressure chamber was ‘relegated’ (in his words) to an ‘ancient’ press, dating from the turn of the twentieth century, that was only capable of pressing 400 tons and still ran on water pressure. Hall would later describe how this press ‘leaked so badly that rubber footwear, mop, and bucket were standard accessory equipment’.
Using this antique press, Hall managed to compress his pressure chamber to ten gigapascals (about 100,000 times the pressure of the atmosphere) and to heat the reaction chamber to 1,600°C. The experiment ran for 38 minutes. Hall had created diamonds:
I broke open a sample cell after removing it from the Belt. It cleaved near a tantalum disk used to bring in current for resistance heating. My hands began to tremble; my heart beat rapidly; my knees weakened and no longer gave support. My eyes had caught the flashing light from dozens of tiny triangular faces of octahedral crystals that were stuck to the tantalum and I knew that diamonds had finally been made by man.
General Electric reproduced Hall’s results 20 times over the next two weeks and on 15 February 1955 announced to the rest of the world that it had created the first diamonds in the lab. In its press release, it implied that the diamonds had been created in their new thousand-ton press. Hall’s reward was a modest salary increase – from $10,000 to $11,000 per year – and a ten-dollar savings bond. He resigned from General Electric to become a full professor at Brigham Young University. …
Hall, meanwhile, was forbidden from disclosing details about the belt press he invented, or using it to pursue further research into high-pressure chemistry, because of a secrecy order imposed by the United States Department of Commerce. During the Second World War, the supply of diamonds had been a source of anxiety for both the Allied and Axis powers. The United States, which did not have a domestic supply of diamonds, was dependent on the De Beers cartel for the diamonds necessary for its industrial production, and the business model of De Beers was to drive up prices by artificially restricting the world’s supply.
