In fact, diamonds are some of the hardest rocks on Earth. At normal atmospheric pressure , diamonds will not evaporate at all. If diamonds are too tough to evaporate , how do they turn to vapor? They oxidize. Oxidation describes a chemical reaction in which oxygen interacts with other substances. Oxygen is a major part of our atmosphere , and substances oxidize all around us, all the time. Rust , for instance, is an example of the oxidation of iron.
Rust is also known as iron oxide. Diamonds are a form of pure carbon. As carbon oxidizes, the chemical reaction forms the everyday gas es carbon dioxide and carbon monoxide. These are the vapors that a diamond becomes at such high temperatures. In the absence of oxygen, diamonds can be heated to much higher temperatures. Above the temperatures listed below, diamond crystals transform into graphite. Howe, L. Jones, and A. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
Media If a media asset is downloadable, a download button appears in the corner of the media viewer. There's a lot of pressure, the weight of the overlying rock bearing down, so that combination of high temperature and high pressure is what's necessary to grow diamond crystals in the Earth. As far as we know, all diamonds that formed in the Earth formed under those kinds of conditions and, of course, that's a part of the Earth we can't directly sample.
We don't have any way of drilling to that depth or any other way of traveling down to the upper mantle of the Earth. The diamonds that we see at the surface are ones then that are brought to the surface by a very deep-seated volcanic eruption.
It's a very special kind of eruption, thought to be quite violent, that occurred a long time ago in the Earth's history. We haven't seen such eruptions in recent times. They were probably at a time when the earth was hotter, and that's probably why those eruptions were more deeply rooted. These eruptions then carried the already-formed diamonds from the upper mantle to the surface of the Earth.
When the eruption reached the surface it built up a mound of volcanic material that eventually cooled, and the diamonds are contained within that.
These are the so-called Kimberlites that are typically the sources of many of the world's mined diamonds. One of the things we know, therefore, about any diamonds that were brought to the surface is that the process of the Kimberlite eruption bringing the diamonds from the upper mantle to the surface of the Earth had to happen very quickly, because if they were traveling too long and too slowly they would have literally turned into graphite along the way.
And so by moving quickly they essentially got locked into place into the diamond structure. Once the diamonds have been brought from high temperature to low temperature very quickly—and by quickly, we mean in a matter of hours—these eruptions, these Kimberlite pipes moving to the surface, may have been traveling at rates of 20 to 30 miles per hour. Once the diamonds are brought to the surface and cooled relatively quickly, those carbon atoms are locked into place and there's just not enough energy to now start rearranging them into graphite.
Diamonds are made of carbon so they form as carbon atoms under a high temperature and pressure; they bond together to start growing crystals. Because of the temperature and pressure, under these conditions, carbon atoms will bond to each other in this very strong type of bonding where each carbon atom is bonded to four other carbon atoms. That's why a diamond is such a hard material because you have each carbon atom participating in four of these very strong covalent bonds that form between carbon atoms.
So as a result you get this hard material. Again where the carbon is coming from, how quickly they're growing, those are all still open questions, but obviously the conditions are such that you've got some group of carbon atoms that are in close enough proximity that they start to bond.
As other carbon atoms move into the vicinity they will attach on. That's the way any crystal grows. The first definitively man-made diamond was created in the General Electric laboratory in This first artificial diamond was created through the process of High Pressure High Temperature HPHT , which tries to replicate nature by superheating and applying force to diamond seeds.
Synthetic diamonds are more commonly made using Chemical Vapor Deposition CVD , which can take 28 days starting with diamond seeds that are superheated in plasma and resulting in a cube-shaped diamond. We often take for granted how the products we use every day are made and most of these products will become obsolete in mere months.
The crown jewel in your engagement ring, necklace, or earrings has probably been taken for granted up to this point, but these indestructible stones will never become obsolete. When purchasing a diamond, whether made by mother nature or man, be sure to consult your Diamond Pro for unbiased reviews of the top diamond retailers globally. Before you buy a diamond, get personal buying advice from industry veterans. We'll help you get the best diamond for the money.
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