Diamond crystals with graphite inclusions synthesized during the experimental modeling of natural diamond formation in chloride and carbonate systems under mantle PT-conditions were studied to elucidate the specifics of the protogenetic graphite inclusions. It has been established that the inclusions of graphite, both primary ones and those resulted from sodium oxalate decomposition, form compact clusters of grains and plates of different shapes in diamond. Diamonds rich in graphite inclusions are black and opaque. Their distinctive feature is significant low-frequency shift (to 1328 cm–1) and broadening (to 6.5 cm–1) of the Raman line, testifying to high residual deformation. Based on the data of previous experiments and the results obtained in this study, we consider peculiarities of protogenetic, syngenetic, and epigenetic graphite inclusions in diamond and their possible use as typomorphic features for the investigation of natural diamonds and reconstruction of their genesis.