Filmed and edited by Petros Gioumpasis. Produced by Vanessa Kortekaas and Henry Sanderson.
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We're here at Cardiff Diamond Foundry. We're able to grow gem diamond, and to do so, we actually start with a diamond seed. So here, I have some examples of some diamond seeds that are grown by high pressure. They're yellow because they contain nitrogen, and this is very common in synthesis. In the high pressure synthesis, you grow at very, very high pressures, and in this technique, I'm going to grow at lower pressures.
So first, I'm going to put the seed into the chemical vapour deposition system, which grows the diamond. And now, what I'm doing is I'm pumping down the reactor. That is, I'm sucking all the air out of this chamber in which the diamond's in. So as we're standing now at 1 atmosphere, I'm actually sucking all the air right, down to a billion times lower pressure to remove all air from the system.
So now, we've pumped all of the air out of the chamber, and we have just a vacuum. So there's no gas flying around within this chamber. What I'm going to do now is I'm going to flow in hydrogen gas. So hydrogen is one of the most important things we need for diamond growth in chemical vapour deposition. And what I'm going to do now is I'm going to activate the hydrogen with microwaves.
Now, if you take a solid and you heat it, you get a liquid. If you take a liquid and heat it, you get a gas. If you heat gas a lot, you get a plasma, which is an ionised gas. It's like lightning you see during thunderstorms. Plasmas you also see in fluorescent lighting, and we are using the same technology to create a very strange chemistry under which we can grow diamond.
Now we're adding methane into the chamber. When the methane gas gets into the chamber, it's broken down by the activated hydrogen into the carbon-containing growth species that grow diamonds. The hydrogen is important, because it stops the carbon from growing into non-diamond carbon, into graphite. You can see in this purple cloud now, diamond is being grown as we speak. If we leave the system for long enough, it will grow around a carat of diamond in a week.
So this is the finished product. This diamond has been cut thin for industrial applications, but of course, we can grow them thicker and cut them in the more standard jewellery format. The important thing is these diamonds are actually chemically identical. The key difference though is a synthetic diamond is actually much purer than the natural diamond.