The classical methods for the study of water-dispersed diamond systems have been used in this paper. The dispersed phase, which was obtained by the detonation method, has been divided into eight fractions during sedimentation. According to X-ray diffraction data, all fractions contained diamond and graphite. The distribution functions of particles and their aggregates by size in disperse systems containing particles of these fractions have been determined by the methods of dynamic light scattering and electro optics. It has been shown that the main influence on the refractive index is exerted by particles that are much smaller than the wavelength of light, while the particles that are commensurate with it change the turbidity of the studied disperse systems significantly without practically affecting their refractive index. It has been shown that the molecular optical calculation of the increase of the refractive index of the systems that contain particles of these fractions is consistent with the results of its experimental determination if the ratio of the particle sizes to the wavelength of light does not exceed 0.1. This allows the determination of the proportion of diamond and graphite in the dispersed phase of the detonation diamond. The values of the increase of the refractive index of the studied systems that were determined according to the Mie light scattering theory are slightly higher than the experimental ones. It has been shown that the theory of light scattering by spherical particles can be used in the calculation of the light scattering indicatrix by disperse systems of detonation diamond.