Making real diamonds from Scratch

Hey! Recently I released a video about carbon, one of the strangest chemical elements because of its unusual properties. Sometimes carbon is also quite expensive, as nowadays a carat of well-cut diamond consisting of pure carbon can cost $15,000. I wonder how much a homemade diamond would cost, and how it could be synthesized. That's what we're going to figure out today, together. I think you already know that the diamond is the hardest natural material currently known on Earth, which makes it pretty expensive. Even a synthetic diamond of high quality can cost $2,000 a carat. The bigger the diamond, the higher the price. Actually, the price for these precious stones can grow exponentially, depending on the size. In fact, natural diamonds would cost the same or even cheaper if it weren't for the monopoly of the American company De Beers, which controlled the precious stone mining market for almost the entire 20th century. And it's worth noting that in 2011 it was practically bought out by the British company Anglo American, which also mines most of the platinum group metals, coal, and other metals. As a result, the price of natural diamonds has only continued to rise. This is why scientists have already produced many other hard materials substituting expensive diamonds. Let's take a closer look at some of them and compare their properties with brilliant diamonds. One of the hardest currently known materials is silicon carbide, which is only three times softer than diamond, but almost a million times cheaper. It scratches ordinary window glass just as easily as diamond, but due to its low price, it's also used as a cheap abrasive in the discs for the angle grinders. Another interesting property of silicon carbide is that it absorbs microwave radiation very well, which means that the crucible covered with this substance heats up in the microwave within minutes and can be used for simple experiments on melting glass or even some metals. The production of silicon carbide is a fairly simple process. All you need to do is heat very pure quartz sand with carbon at a temperature of about 3600 degrees Fahrenheit, after which the resulting silicon carbide powder can be sintered into plates. By the way, they are used in many modern composite body armor vests due to their lightness and effectiveness in stopping incoming bullets. Even though silicon carbide ceramics are easily shattered when hit by a bullet, the latter loses almost all of its energy and gets retained by the other layers of the vest. Using a different method of silicon carbide production, such as vapor deposition, it is possible to obtain the rare minimal moissanite, which is extremely close to diamond in terms of refractive index, thermal conductivity, and hardness. For this reason, this gem is often used as a diamond imitation. After all, even a common tester can't distinguish a diamond from a moissanite fake, which costs hundreds of times less. Besides silicon carbide, we should mention another material with a hardness comparable to that of a diamond. It's boron nitride, the so-called hexagonal modification of which looks like an ordinary white powder. It's obtained in special furnaces where boron oxide and ammonia react with each other at a temperature of 1,650 degrees Fahrenheit, with a nitrogen gas blowing through a quartz tube to create a protective, oxygen-free environment. By pressing the obtained powder, it's possible to make crucibles, which are particularly suitable for working at high temperatures, especially taking into account that molten metal does not stick to them. This white modification of boron nitride is quite soft, though if you gently compress and heat it, you can get a cubic form of boron nitride, which is one of the hardest known materials. Cubic boron nitride is only a little softer than diamond, but it's not that brittle and more chemically resistant. Moreover, it's much cheaper than even artificial diamonds. Nowadays, this material is used to make quite expensive metal lathe tools. For example, this one costs $20, even though the only thing made of boron in it is this small tip. The rest is hard steel. Such lathe tools are commonly used for processing hard steel and cast iron, but if you want to get, for example, an aluminum piece with a mirror surface, you'd better use diamond-tipped lathe bits with polycrystalline diamonds. But still, how can we produce any kind of diamond? For this purpose, it's necessary to take some cheaper form of carbon, for example, graphite, which can be found even in natural form. In nature, diamonds are formed when graphite sinks deep underground along with the descending lithospheric plate. The required pressure and temperature of about 1,800 degrees Fahrenheit are reached at a depth of 100 miles, where the graphite begins to form new bonds and turn into diamonds. This process is not fast and can take thousands of years until the volcano finally erupts, forming so-called kimberlite pipes and delivering the formed diamonds to the surface along with lava flows. These days, it's possible to get diamonds much faster, so you don't have to wait thousands of years. Just like in nature, it requires very high pressure and temperature, which can be found in the epicenter of a powerful explosion. Yeah, that's right. If you take a cheaper and more ordered form of carbon, for example, graphite powder, and cover it with explosives, the explosion of which generates a pressure of tens of gigapascals and a temperature of more than 3,600 degrees Fahrenheit, carbon atoms will form new bonds, and the graphite will turn into a diamond. The only pity is that the chemical explosion process lasts for a very short time, so you're only going to get the finest powder of nanodiamonds, which can be sintered to obtain polycrystalline diamonds, for example, the one used in this diamond-tipped glass cutter. The advantage of polycrystalline diamonds is that they're cheaper and less brittle than the usual monocrystalline diamonds commonly found in jewelry. Besides explosion, diamonds can be obtained in another unusual way that also involves high pressure and temperature, and lasers. I can hardly show it in my condition, so I went to the Moscow Scientific and Technological Center of the RAS, where scientists are engaged in experiments to create the hardest materials, which might even surpass diamonds in some of their properties. For their experiments, scientists use a special high-pressure cell in which any substance can be compressed with a force more than 200,000 atmospheres. This cell contains two very high-quality artificial diamonds cut with the highest precision in a special way, forming the so-called diamond anvil. These diamonds are embedded extremely evenly and precisely opposite to each other, so that it would be possible to make a tiny chamber for creating ultra-high pressure between such diamond anvils. Before creating high pressure in the cell, it's necessary to make the body of the tiny chamber in which the compressible substance will be placed. It can be made of different metals, for example copper or tantalum, but this time we decided to use ordinary iron, as it's cheap and it's easy to make a hole in it with a diameter of only half a millimeter. It's burned with a powerful pulsed laser in just a few seconds, after which this small piece of foil should be fixed in the cell on one of the diamonds. The operation is quite fiddly and constantly requires the use of a microscope, but researcher Camille copes with it perfectly. By the way, thank him for his help with this experiment. After a piece of iron is placed on one of the diamonds, it's pressed with another diamond to form the compression chamber. This can be done by lightly pressing the upper part of the cell, as all the pressure is transferred to the After which, the iron plate gets the indentation for the chamber in the shape of a cut diamond. This is a 250 micron diamond imprint. It's interesting, by the way, that in such a chamber between diamonds, you can compress even ordinary water at a pressure of 200,000 atmospheres. It just freezes, even at room temperature. The physical properties of some substances can be quite unusual. Unfortunately, our high pressure chamber was constantly displaced, and even experienced laboratory workers failed to compress water between the diamonds, after which we decided to proceed to the synthesis of the diamond. To do this, we took another piece of iron foil with a hole in it and compressed it between the diamonds one more time to create a high pressure chamber. After that, we decided to fill it with the initial substance for diamond production, namely graphite, but before it needs to be lightly salted. Yes, that was not a joke. In order to evenly distribute the pressure in the chamber, you have to add ordinary table salt. It becomes softer at high pressure and fills the voids between the graphite particles. Because of its tiny size, the chamber should be filled very carefully. Any inaccuracy or displacement can ruin the whole entire experiment. It takes some time to put a sodium chloride crystal into a tiny hole in the chamber, after which the cell is again slightly compressed to make the salt spread evenly between the I can see that. The salt is spreading. We did it. After that, Camille began to add pure graphite to the chamber, which would eventually turn into a diamond. This must be done with surgical precision, so that the graphite particles fall precisely between the compressed salt. Now the graphite needs to be salted a little more to better compress it from all sides. Camille then tightens the screws of the cell, increasing the internal pressure between the to 200,000 atmospheres, as well as all the pressure of the screws is applied to the tiny culets, between which the above-mentioned salted graphite is compressed. After reaching the required pressure, you can clearly see under the microscope that the graphite particles are concentrated in the center of the chamber, while the salt has reached a kind of semi-liquid state due to the high compression and spread around the edges of the chamber. But still, the graphite hasn't turned into a diamond at ordinary room temperature. For its transition to another allotropic form, it must be heated, like with the help of a powerful laser. I guess you've already realized that in order to synthesize a diamond at high pressure with the help of a laser, you need to use two more diamonds. Sounds strange, I know, but such a high-pressure cell simply doesn't work any other way, because other solid materials, for example the already mentioned boron nitride, is not transparent and hardly can be cut as finely as artificial diamonds. After all the preparations are done, we bring the cell to another lab. There's a special laser unit capable of heating the graphite inside the high-pressure chamber to several thousand degrees Fahrenheit. The laser source used here is a powerful infrared laser diode that can easily ignite an ordinary wooden block. Let's add more power. That's fine. Is that enough? Burn it! And as if that wasn't enough, the well-focused beam easily burns through even a metal coin. We heated it up pretty well. Before synthesizing a diamond, the high-pressure cell must first be centered so that the laser hits the compressed graphite particles, not the salt layer. In order to make this process easier, we use a special camera with a modified spectral range, which allows us to see the contents of this cell very clearly, just like through a microscope. By the way, this camera is more expensive than any of the most sophisticated professional cameras. After all the preparations are made, you just need to turn on the laser and heat the graphite section to a temperature of 5,500 degrees Fahrenheit. This makes the entire contents of the chamber shine like a light bulb, and the image on the camera becomes overexposed because of that powerful glow. In that instant, the carbon atoms of graphite form new bonds and turn into a diamond. And basically, that's it. A small diamond has been formed on this heated area. It's even a slightly different color from the surrounding graphite, which you can clearly see under a microscope. The white is salt. See the cloudiness around the graphite? That is a diamond. To prove to you that this is a real diamond, we also conducted a Raman spectroscopy of the recently obtained section. Do you see the graph of the spectrum? This peak proves we've actually obtained a diamond among the graphite. Besides this usual diamond, such cells can be used to produce super-hard boron compounds, as well as some other crystals whose hardness can be comparable to that of a diamond, or even exceed it. For example, minerals like stishovite or fullerite, which according to some data even surpass diamond in hardness. Okay, now you know how to produce microscopic diamonds using an explosion or a laser. But how can we produce really big artificial diamonds, like the ones we saw in that high-pressure cell? Or the ones that are used sometimes in jewelry? Nowadays, the industry mainly uses two methods to synthesize large diamonds. The first method is similar to the natural process, which involves high pressure and high temperature. The diamonds are grown in special presses, like this one. Looks pretty impressive, right? A capsule containing a high concentration of graphite in a metal shell is placed in this machine, weighing more than 5 tons. The capsule also contains a seed of the future diamond, a tiny and very pure diamond, which will accumulate new carbon atoms and become bigger and bigger over time. After that, the press creates a pressure of 60,000 atmospheres and heats up to 2700 degrees Fahrenheit for several days or even weeks, creating conditions similar to those found at a depth of 100 miles inside the planet. Under these conditions, the graphite begins to melt, and atom by atom, the diamond seed gets covered with new layers of carbon, thus increasing in size over time. This way, a diamond can be grown to any size. Everything depends only on the patience and requirements of the customer. These days, a press like this costs half a million dollars each. Some grown pure diamonds are even more expensive, so unfortunately, I couldn't find out all the details of growing really big diamonds, as for most companies, it's considered a trade secret. The produced diamonds often contain nitrogen impurities, making them slightly yellowish. The standard shape for these diamonds is an octahedron. In order to grow a transparent diamond of any other shape without any shades, it's necessary to use the method of chemical vapor deposition, which is quite similar to the method used for coating kitchen utensils or drill bits with titanium nitride. The only difference is that, instead of titanium and nitrogen, the chamber is filled with carbon vapor, which, under high pressure and temperature, begins to deposit on the surface of the seed, atom by atom, forming a diamond of absolutely any shape and perfect clarity. These diamonds are used in very rare scientific experiments, as well as for creating pieces of jewelry when the customer demands the highest purity and transparency of a precious stone with a price four times less than that of a natural gem. Well, I think after watching this video, you've learned more about the production of diamonds and why even artificial gems are fairly expensive. And if you've enjoyed this video, as always, don't forget to give it a like and subscribe to the channel to see many more new and interesting things.