Abstract: Diamond is one of the hardest minerals on earth, and its formation environment is quite demanding. The mineralogical features, inclusion characteristics and carbon stable isotope composition of diamond record the information of temperature, pressure and material composition in the geological process of diamond growth, erosion and transportation. Therefore, the characteristics of mineralogy, inclusion and carbon stable isotope are the important research objects for exploring the diamond material source, formation processes and physicochemical environment in deep earth. The authors summarized the research findings about the characteristics of diamond mineralogy, inclusion and carbon stable isotope at home and abroad. The results show that the diamond source can be roughly distinguished by the diamond crystal types and combination as well as diamond colors. The diamond surface feature is an important distinguishable characteristic between primary diamond and placer diamond. The research on diamond inclusion types and combination, inclusion chronology and carbon stable isotope can be used to analyze the diamond material source and physicochemical environment in deep earth, and determine the diamond formation period. This research can provide important information for the study of diamond genesis, deep process of lithospheric mantle and crust-mantle interaction.