How Diamonds are Made

The surprising discovery that diamonds are composed only of pure carbon – just like charcoal, or graphite – was not made until the nineteenth century. Immediately, scientists and enthusiasts started trying to solve the problem of how to turn carbon into a man-made diamond.

The difficulty was to build machines capable of generating heat and pressure equivalent to the immense forces of the geological processes that produce natural diamonds in the earth’s crust.  The difference between charcoal or graphite and diamond is that the carbon atoms in diamond have been forced into a dense, regular lattice of tiny interconnected cubes. That requires heat sufficient to melt rock and the kind of pressure that raises mountain ranges. The result is compressed carbon of tremendous hardness, brilliance and transparency – the qualities which, along with rarity and marketing, make diamonds valuable as gemstones.

The first man-made diamonds emerged from America and Sweden in the early 1950’s. General Electric were the first to announce diamond synthesis using a high-pressure, high-temperature ‘anvil’. (The term HPHT is still used today to describe many synthetic diamonds made using this technique.) The stones produced in the 1950’s were small and imperfect – not suitable for gemstone use. But in the 1970’s, General Electric again made diamond headlines by producing the first synthetic gem-quality diamond. Since then, diamonds of up to 25 carats (5g) have been produced for research purposes, but generally diamonds are only synthesized to around a carat. The high-pressure, high-temperature press has to be kept stable for a week to produce gems of this size, which is expensive.

CVD (Chemical Vapor Deposition) is currently the only other commercial method of synthesizing gemstone-quality diamonds. This technique involves energizing carbon vapor so that it will deposit carbon atoms onto a substrate at relatively low temperatures and pressures. This allows the formation of thin diamond ‘sheet’ on a variety of surfaces, which is extremely useful in many technological applications. It can also be used to create pieces of diamond large enough to be cut into gems.

Created diamonds are one of the most fascinating inventions of the decade. Learn more at My Lab Created Diamond, including a history of synthetic diamonds, and more about other created stones and diamond simulants.

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