There are two main methods to produce synthetic diamond. The original method is High Pressure High Temperature (HPHT) and is still the most widely used method because of its relative low cost. It uses large presses that can weigh a couple of hundred tons to produce a pressure of 5 GPa at 1,500 degrees Celsius to reproduce the conditions that created natural diamond inside the Earth billions of years ago. The second method, using chemical vapor deposition or CVD, was invented in the 1980s, and is basically a method creating a carbon plasma on top of a substrate onto which the carbon atoms deposit to form diamond. http://en.wikipedia.org/wiki/Synthetic_diamond#Manufacturing_technologies Synthetic Diamond is diamond produced through chemical or physical processes in a factory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Due to its extreme physical properties, synthetic diamond is used in many industrial applications, and has the potential to become a serious disruptive technology in many new application areas such as electronics and medicine. Synthetic diamond is also called industrial diamond, manufactured diamond, artificial diamond or cultured diamond. Synthetic diamond is not the same as Diamond-like Carbon, DLC, which is amorphous hard carbon, or diamond imitation, which can be made of other materials such as cubic zirconia or silicon carbide. http://en.wikipedia.org/wiki/Synthetic_diamond