CVD diamond is a chemical vapor deposition method in the laboratory, using a mother stone (diamond crystal with a diameter of 10 to 30 nanometers) as a substrate, and using the principle of microwave heating to continuously deposit carbon atoms in methane on the diamond substrate. Layer by layer, the diamond will quickly "grow up" on the basis of the substrate. That is to say, a CVD diamond is a kind of laboratory-grown diamond, that is, a man-made diamond. Natural diamonds are formed naturally under extremely high temperatures and pressure inside the earth after a long history. Synthesis is made by polymerizing carbon into crystals through different methods in a short period of time in an artificial environment.