How The First Non-Natural Diamond Was Grown In A GE Lab

Since ancient times, people have tried to make their own diamonds. In upstate New York in 1954, it finally happened.

The following is an excerpt from Genuine Fakes: How Phony Things Teach Us About Real Stuff by Lydia Pyne.

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Genuine Fakes: How Phony Things Teach Us About Real Stuff


The first non-natural diamonds were made in General Electric’s laboratories in December 1954.

Ever since Lavoisier and Tennent’s experiments, scientists and engineers had known that they needed to subject carbon to enormous amounts of heat and pressure in order to transform it into a diamond, but just how to pull this off required no small amount of trial and error. As demonstrated in the experiments of Hannay, Moissan and even Parsons, creating immense amounts of pressure is difficult, if not downright dangerous. But, their early experimental designs weren’t necessarily flawed—they just needed different technologies and manufacturing to be able to create those pressures in the lab. The answer came from the American Nobel-winning physicist Percy Bridgman, who worked with the development of a vertical hydraulic piston that pressed into a cylinder, which created 4,200 atmospheres of pressure through a complex anvil system. For years, Bridgman’s laboratory at Harvard had holes in the walls where the canister—affectionately known as ‘The Bomb’—blew out and embedded materials in the walls. Bridgman, it was reported, superstitiously never had the holes repaired.

By the 1940s, the General Electric Research Laboratory in Schenectady, New York, had become the centre of synthetic diamond research, bringing together researchers from chemistry, physics and industrial engineering. (Schenectady had a long tradition of supporting speculative research projects even if they weren’t directly related to the production of electrical equipment.) The team was made up of Francis Bund, Herbert Strong, Howard Tracy Hall (generally H. Tracy Hall or Tracy Hall in popular literature), Robert Wentorf and James Cheney, and was managed by Anthony Nerad. The project was code-named “Project Superpressure” and everyone was sworn to secrecy. Drawing on Bridgman’s work, Superpressure used several different apparatuses in its experiments. For years, the team devoted extraordinary time, effort and resources to making synthetic diamonds—and, more importantly, to learning how to manufacture them in a way that was replicable. As the years went by, the management at General Electric began to worry that manufacturing diamonds would turn out to be gimmicky at best and a total monetary sinkhole at worst. By December 1954, the team needed concrete, tangible results—diamonds—to justify its work.

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On the evening of 8 December 1954, Herbert Strong began Experiment 151, setting the pressure cone apparatus at an estimated 50,000 atmospheres, cranking the temperature up to 1250°C (2282°F), and depositing a carbon and iron mixture with two small natural diamonds to seed diamond crystal growth. It was not unlike the methods used by Hannay decades earlier, only Strong was clearly using seed crystals. (Research in the Soviet Union used seed diamonds as part of the effort to grow diamonds, as near as General Electric could tell.) Most of Strong’s earlier experiment runs had been short, a couple hours at most. But this time he decided to let Experiment 151 mimic nature—which took millions of years to produce diamonds—and, at least, to extend the time of the experiment and let it run overnight.

On the morning of 9 December, the two seed crystals tumbled out freely, unchanged in the crucible. A blob of the iron-carbon mixture had melted into one end of the tube and Strong sent the blob to the metallurgy division to be polished. A bit miffed, metallurgy sent back a message on 15 December, informing Strong that they were unable to polish his sample because it was destroying the polishing wheel. Whatever was in the blob was strong and hard—hard enough to gouge metallurgy’s equipment—and only a diamond could be that tough. Strong recounts, “The entire group gathered around to inspect the hard point. Initially there was a moment of stunned silence. Could it possibly be diamond? Finally, Hall spoke the verdict: ‘It must be diamond!’” Subsequent X-ray analysis confirmed that the diamonds in question were, in fact, laboratory made.

“Instantly, my hands began to tremble. My heart beat wildly. My knees weakened and no longer gave support. Indescribable emotion overcame me and I had to find a place to sit down!”

On 16 December 1954, Hall performed a similar experiment by himself, using an older bit of technology, a high-pressure press called a belt. He added two diamond seed crystals to iron sulphide and placed everything in a cylindrical graphite heater. Carefully following the belt protocol he had designed after months of working with the apparatus, he placed thin disks of tantalum metal between the sample and the belt anvils to facilitate current to heat the sample. Everything was cooked at 1600°C (2912°F) under 100,000 atmospheres of pressure. The entire experiment took 38 minutes.

“I broke open a sample cell after removing it from the Belt. It cleaved near that tantalum disk,” Hall said of his discovery, after seeing flashes of light from octahedral crystals that were stuck to the disk. “Instantly, my hands began to tremble. My heart beat wildly. My knees weakened and no longer gave support. Indescribable emotion overcame me and I had to find a place to sit down!” In Hall’s mind, there was no doubt about the results. “I knew that diamonds had finally been made by man.”

Suddenly, after years of research and in the space of a mere week, General Electric had two possible ways to manufacture diamonds. In the weeks that followed the question wasn’t so much whether researchers could make diamonds. The question was whether they could make them again according to either Strong’s or Hall’s experiment designs. Which method was better?

Researchers spent weeks trying to duplicate Strong’s results and never could. (Strong contended that the heat had fluctuated significantly during the night of Experiment 151 and that fluctuation played a role in the run’s success—serendipity as its finest.) Hall, working with Robert Wentorf, verified his original results rather decisively. Over the next two weeks the two of them successfully made diamonds 20 times, using Hall’s 400-ton press and belt system. On 31 December 1953, General Electric had physicist Hugh Woodbury independently confirm Hall’s diamond-making methodology.

Like many discoveries in the history of science, pinpointing exactly who ought to be credited with a discovery—and who history has credited—is a bit tricky, and the story of who manufactured the first synthetic diamond and when is no exception. In a series of publications, Strong has highlighted the work that the group did, pointing to the complicated nature of the problem and emphasizing that the work was beyond what one man could claim to do.

Hall, on the other hand, felt ostracized from the team. (As a practicing member of The Church of Jesus Christ of Latter-day Saints, he claimed to have been on the receiving end of religious prejudice during his tenure at General Electric.) He also felt underappreciated by the company: General Electric increased his salary from $10,000 to a mere $11,000 between 1953 to 1954, and paid him a $10 savings bond, despite making millions from his work. (This was somewhat typical for a Cold War research laboratory. Corporate scientists signed over the rights of their intellectual property to their parent companies and often received small bonuses like this one in connection with any patents that resulted from their work.) Hall left General Electric in mid-1955 to take a faculty research position at Brigham Young University, and authored several patents related to the manufacture of synthetic, laboratory-grown diamonds. He also started the company MegaDiamond, which eventually became General Electric’s biggest domestic competitor in the diamond-making business. Both Hall and Strong have claims to be “the first” to create diamonds, although most tellings of the story credit Hall because of the replicability of his experiments.

General Electric published the results of its laboratory- grown (or “man-made” or synthetic in the parlance of the mid-twentieth century) diamonds on 15 February 1955. Reporters were invited to check the laboratory-made diamond dust under a microscope, and the research team was under strict instructions to keep mum about details of its work. Between February and March 1955, newspapers across the country blurbed General Electric’s success, but were short on technical details for their readers. Most of those quoted in articles were jewelry experts, who dismissed these diamonds as any sort of financial challenge to the diamond market at that point. In the following months, General Electric held several more press events (one, for example, in May 1955, was at the Sheraton Hotel in Rochester, New York), which talked up not only the engineering prowess of its synthesized diamonds, but also how the project would be a “boon to US industry.”

Reprinted with permission by: Bloomsbury Sigma, Bloomsbury Publishing Plc, Bedford Square, London UK. First published in the United Kingdom in 2019. Copyright © Lydia Pyne, 2019

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About Lydia Pyne

Lydia Pyne is a writer and science historian and a visiting researcher in the Institute for Historical Studies at the University of Texas at Austin in Austin, Texas.

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