1. high temperature and high pressure synthesis method: temperature and pressure are still two key factors in making crystals. According to professionals who are engaged in diamond jewelry, the method is to make diamonds in ceramic containers instead of underground. High pressure is provided by water pressure, and high temperature is generated by electricity, so that carbon surrounds the seed crystal with a diameter of 1mm and forms crystals.

2. Chemical vapor deposition synthesis method: after natural gas and nitrogen are heated, carbon plasma is formed in a pressure chamber the size of a dishwasher. Plasma is continuously deposited on the carbon bottom layer at the bottom of the pressure chamber, and gradually accumulates and hardens to form diamond slices, which are then cut into gem shapes.