Diamond and synthesis process thereof

The synthetic process comprises the following steps: S1, selecting a single crystal diamond with a flat surface as a seed crystal, and polishing the growth surface of the single crystal diamond with the growth surface being a (100) surface; s2, cleaning the seed crystal, and then putting the seed crystal into a cavity of microwave plasma chemical vapor deposition equipment; s3, H2 is introduced into the cavity, the flow rate of H2 is 100-1000 standard ml/min, and the seed crystal is etched; and S4, after etching is completed, a carbon source is introduced into the cavity, the volume ratio of the carbon source to H2 is 1%-12%, stable growth is carried out, the concentration of the carbon source is reduced by 0.1%-0.5% every 50-199 hours of stable growth, and other process parameters are kept unchanged until the target thickness is reached. According to the method, long-time stable operation of equipment is maintained through a method of periodically controlling the concentration of the carbon source, the diamo