From Smoke To Diamonds: Transforming CO2 to Precious Gems

A revolutionary environmentally-conscious process has allowed for the production of synthetic diamonds using carbon dioxide from the air.

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By Iris Lin

Diamonds are the hardest naturally occurring substance on Earth. Considering their timeless beauty and elegance, as well as the intensive mining labor required to obtain them, it’s no wonder that they have a hefty price tag. A recent discovery, however, could allow for diamonds to be created out of thin air—literally.

Diamonds are the only precious gem composed almost entirely of one element: carbon. Their chemical constituents are 99.95 percent carbons, with the remaining 0.05 percent composed of trace minerals. Diamonds are naturally formed in the Earth’s mantle about 100 miles below the surface, where carbon is exposed to extreme temperatures—ranging from 900 to 1,300 degrees Celsius—and intense pressure—ranging from 45 to 60 kilobars (compared to the significantly lower sea-level atmospheric pressure of approximately one bar). As a result of the intense conditions that must be met, it takes millions of years for diamonds to form naturally.

Since humans have not yet developed the technology required to mine deep enough below the Earth’s surface, most of the world’s diamonds are extracted from the remains of volcanic activities. During a volcanic eruption, diamonds are only brought to the surface if they are transported extremely quickly from below. If it takes more than a matter of hours for the diamonds to surface, they become graphite due to too much heat exposure. Before they surface, their carbon atoms mainly resemble the structure of a traditional lattice but still shift and vibrate slightly. After the diamonds surface, their molecules freeze into their permanent crystal lattice structure, where they remain in their rigid diamond state. These diamonds are found in Kimberlite pipes, which are vertical and horizontal streaks of igneous rock formed from the volcanic eruption’s magma and run along the surface, often in craters or valleys. 

Mining diamonds comes at a cost, contributing to countless humanitarian and environmental issues. Oftentimes, miners are given inadequate wages and work in inhumane conditions, leading to increased risks of cancer, hearing loss, lung collapse, and other health complications. Environmentally, diamond mining can also cause soil pollution, groundwater contamination, and air pollution.

Synthetic diamonds, which may provide a potential solution to many of these ethical and environmental concerns, are becoming increasingly popular. They look identical to real diamonds in shape, size, color, hardiness, and clarity grades, and they also have the same chemical properties. They are created in a process that mimics the intense heat and pressure conditions natural diamond formation requires but form in a matter of weeks rather than millions of years. Most synthetic diamonds are produced in a press (a machine that applies an extreme amount of pressure to an object by squishing it almost infinitely from both sides) containing a small cut of diamond, a metal catalyst (often nickel), and a block of pure carbon. The press subjects these materials to 1,600 degrees Celsius and intense pressure. The high pressure and temperature break apart the block of pure carbon and activate the catalyst. Then, the carbon—with catalytic assistance—is free to start building up in a crystalline structure, ultimately producing the full synthetic diamond.

Synthetic diamonds can also be created through the general process of chemical vapor deposition (CVD). In CVD, a thin layer is cut from any pre-existing material and then exposed to a superheated plasma composed of vapor. Chemical reactions make the vapor transform into a solid, and those resulting solid pieces build upon the pre-existing piece. CVD is a multipurpose process used for generating new material or coating existing material, and it is also used for synthetic diamond manufacturing.

The European synthetic diamond manufacturing company SkyDiamonds produces synthetic diamonds with little more than rainwater and air. SkyDiamonds utilizes CVD, tailoring it specifically to diamond creation to produce carbon dioxide-minimizing precious gems. First, the water molecules in the rainwater are split into hydrogen and oxygen atoms through electrolysis. Electrolysis is the process by which an electric current initiates an oxidation-reduction reaction, rendering a chemical change to a substance—in this case, generating hydrogen from pure water. The hydrogen molecules are then exposed to gaseous carbon dioxide (CO2). The carbon atoms detach from the carbon dioxide, form covalent bonds with the hydrogen molecules, and produce copious amounts of methane (CH4). This methane is then superheated using microwave energy generated from solar panels and wind turbines. This creates an extremely heated, electrically charged plasma into which the “starter diamond”—the original thin cut of diamond, akin to the “small, pre-existing material” in CVD—is placed. Carbon atoms from the methane are attracted to the carbon atoms on the diamond, causing the carbon atoms to break their bonds with the hydrogens and deposit onto the starter diamond. This slowly builds a crystalline network atom by atom, eventually forming a full-size diamond. 

CVD is an extremely meticulous process; if not done precisely and accurately—for instance, if the plasma is overheated or the starter diamond is not cut exactly right—it can lead to extremely expensive lead in lieu of a diamond, ultimately wasting time, money, and energy. However, all the carbon atoms in these diamonds had formerly been contributing to global warming. The CVD, therefore, not only prevents greenhouse gas creation but also tangibly removes carbon dioxide from the atmosphere, positively impacting people, the environment, and our planet as a whole. As of right now, millions of dollars and thousands of workers are poured into the diamond mining business, but growing synthetic diamonds costs 50-70 percent less and requires significantly less manpower and equipment. Synthetic diamonds are faster to produce, and the materials needed to make them are much more readily available. With further research and experimentation, this method has the potential to make Earth a healthier planet while still producing the precious gems we cherish.