Key knowledge about CVD diamonds

CVD diamond is a polycrystalline diamond synthesized from diamond crystals with a diameter of 10 to 30 nanometers.

Simply put, CVD diamonds are synthetic diamonds, which can also be called cultivated diamonds. This kind of diamond has been recognized by more and more people in the past two years and is one of the best substitutes for natural diamonds. For many ordinary consumers, CVD diamonds and natural diamonds are very similar in appearance and cannot be distinguished at all.

In 1954, man-made diamonds were successfully synthesized for the first time. At that time, a group of researchers from the American CVD Diamond Company produced a diamond in a laboratory. They imitated the environment that diamonds formed in nature and applied extreme high temperature and high pressure to carbon.

Also in the 1950s, another method of manufacturing synthetic diamonds was successfully developed. This chemical vapor deposition (CVD) method, at very low pressure and relatively low temperature, mixed carbon from carbon The gas is deposited into a diamond matrix.

The quality and appearance of man-made diamonds is indistinguishable from natural diamonds. At the beginning, due to the lack of sophisticated technology of artificial diamonds, diamond dealers can use a very simple method to confirm whether diamonds are grown in the laboratory. They use strong magnets, because there are metal crystals left in the culture process inside the artificial diamonds, strong magnets. Then the diamond can be sucked up.

Synthesis methodedit

1. UPHT (ultrahigh pressure high temperature) synthesis method: temperature and pressure are also the two key factors for crystal manufacturing. The method is to manufacture diamonds in ceramic containers instead of underground. Water pressure provides high pressure, and electricity generates high temperature. The carbon surrounds a seed crystal with a diameter of 1 mm and is made of natural diamond to form a crystal.
2. Chemical vapor deposition synthesis method PECVD (Plasma Enhanced Chemical Vapor Deposition): After heating natural gas and hydrogen, a carbon plasma is formed in a pressure chamber the size of a dishwasher, and the plasma is continuously deposited on the bottom of the pressure chamber. On the carbon bottom layer, it gradually accumulates and hardens to form diamond flakes, which are then cut into gemstone shapes. A high-quality yellow diamond with a size of 8.2mm. This sample is the largest artificial diamond single crystal in the mainland in terms of weight and size. This achievement marks the leading position in the domestic synthetic diamond (jewel-grade diamond) field.