What is CVD diamond?
CVD laboratory cultivation growth diamond is a man-made diamond. To create a diamond growth environment, using chemical vapor deposition (CVD) method, through adsorption and thermal separation of atoms and molecules in gaseous substances. Let carbon ions adhere to grow, forming diamond crystals. So, what is the difference between CVD diamond and natural diamond? Now, let’s have a detailed understanding.
CVD diamond is a polycrystalline diamond synthesized by diamond crystal with a diameter of 10 to 30 nm. In short, it is a kind of diamond cultivated in a laboratory.
The difference between CVD diamond and natural diamond
CVD diamond can be understood as a diamond with the same composition as natural diamond produced by artificial stimulation of diamond growth environment, that is, laboratory diamond, which can be identified and distinguished by authoritative appraisal institute. The production model is the difference between CVD diamond and natural diamond. Of course, natural diamonds are valuable gemstones made from diamonds. Natural diamonds grow under a range of temperatures and pressures. The temperature of CVD is higher than that of CVD. At high temperature, diamonds grow into octahedral crystals. But at low laboratory temperature, they grow into crystals containing both octahedral and cubic faces.
The difference between CVD diamond and natural diamond is that one is formed. Naturally, the other is processed artificially, but the ingredients are the same, they are all pure carbon structure, and the hardness is also the same. It is said that other artificial diamonds are harder than natural diamonds. The Mohs hardness of a natural diamond is 10, which is a complex substance in nature.
The price difference between a natural diamond and CVD cultivated diamond. Price is the embodiment of value, and the value of a natural diamond is needless to say. People who don’t know about CVD diamonds may think it’s very cheap. In fact, it’s not. The production conditions of CVD diamonds are harsh, so the cost of producing CVD diamonds is also high. Even if the conditions are relatively mature, a carat of CVD diamonds will cost thousands of RMB, while a carat of natural diamonds can cost as little as 20000 or 30000, and as much as 70000 Diamond quality.
CVD diamonds are processed artificially, so they are better in clarity and color than ordinary diamonds. It is also the difference between CVD diamonds and pure natural diamonds. Color and clarity have a great influence on the price of diamonds. The quality of natural diamonds can not be generalized. There are good ones and secondary ones. CVD diamonds’ quality is often better, and the fire color produced by CVD diamond cutting is even better.
CVD cultivated diamonds can produce more large grains, while natural diamonds are rare and expensive.
CVD diamond processing methods are mainly two: high temperature and high pressure (HPHT diamond) and chemical vapor deposition (CVD diamond). The CVD method is suitable for the production of large carat diamonds (mainly 1 carat). Chemical vapor deposition (CVD) uses microwave heating, discharge and other methods to activate carbon-based gases. Such as methane, to dissociate carbon atoms and hydrogen atoms, and then combine the free carbon atoms to form diamonds. Generally, CVD diamond synthesis is carried out under low pressure and high temperature. The pressure is usually less than one atmosphere, and the temperature is about 1000 ℃.
7. The growth environment of the difference between CVD diamonds and natural diamonds
Natural diamonds were formed in the deep crust under extremely high temperature and pressure as early as 3 billion years ago from the growth environment. The volcanic activity takes them to the surface. It hides them in a kind of volcanic rock called kimberlite pipe, waiting to be mined. Only about 5% of the kimberlite pipes contain enough diamonds to ensure that their mining is economically feasible, a precious resource that cannot be regenerated.
CVD diamond is cultivated in the laboratory through some unique methods. It is a kind of artificial diamond, which is formed quickly, but it has all the characteristics of a diamond, such as hardness, fire color, refractive index and so on.
8. The difference between CVD diamond and natural diamond clarity
CVD diamond has high clarity, fewer inclusions in it. Moreover, CVD synthetic diamond does not have metal inclusion, so it is not magnetic. There are many kinds of defective inclusions in natural diamonds. But even so, CVD diamond and natural diamond can not be distinguished through this aspect.
Some insiders think that CVD diamond and natural diamond have some color differences. The color of CVD synthetic diamonds in the early stage is mostly dark brown or light brown, while the color of CVD synthetic diamonds discovered recently is colorless or nearly colorless because it has been proved that CVD synthetic diamonds have undergone high-temperature heat treatment in the later stage. So in terms of color, CVD diamond and natural diamond have many similar places, and there is not much difference.
Can CVD diamond be seen?
First of all, it must be made clear that the chemical composition of CVD diamonds is carbon, which is the same as natural diamonds, except that CVD diamonds are synthesized by technical means rather than formed naturally in the process of geological changes. CVD diamond is as like two peas in natural chemistry, chemical composition, crystal structure, optical properties and physical properties. Like natural diamond and CVD diamond are more like human and human cloning. CVD diamond is a real diamond. Therefore, there is no obvious problem. However, the growth rate of CVD diamond is much higher than that of natural diamond. The fluorescence spectrum will be slightly different under high-tech equipment irradiation. However, this kind of equipment is not the top diamond appraisal organization. People usually don’t have this kind of equipment.