RESUMO
From the center to the rim of natural diamond there are differences in nitrogen and C-H bond contents, suggesting that diamond was formed under varying substance conditions. Both the nitrogen and C-H bond contents tend to decrease from the center to the rim as a whole, indicaing that nitrogen and hydrogen are expended little by little during the formation of diamond. But in the middle area of the sample both the nitrogen and C-H bond contents have a tendency to increase. This implies that nitrogen and hydrogen are added into the environment of diamond formation, meanwhile nitrogen is added earlier. So the procedure of diamond formation may be divided into three stages, namely nucleation and growth in the early stage, growth in the middle stage and in the late stage. In the early and late stages nitrogen and hydrogen are consumed in the environment of diamond formation. In the middle stage nitrogen and hydrogen must be replenished for the growth of diamond, and nitrogen should be replenished earlier than hydrogen. Hydrogen is useful to the nucleation and growth of diamond. During the formation of diamond the compounds of nitrogen and hydrogen do not exist. So we must avoid the formation of compounds of nitrogen and hydrogen for the nucleation and growth of diamond if we plan to introduce hydrogen to the synthesis of diamond at high temperature and high pressure (HPHT). Implanted hydrogen in graphite for the HPHT synthesis of diamond is a good choice.