The study of light scattering of aqueous colloids of diamond with particle size 10–400 nm was conducted. Particle concentration in colloids was low, and light scattering could be considered single. Methods of static, dynamic, and electric light scattering were employed. During the static light scattering experiments we took into account particle distribution on size that was determined from electron microscope measurements. It was shown that the experimentally obtained indicatrix of light scattering of polydisperse non-spherical diamond particle solution is in good agreement with the theoretical one for spherical particles. Autocorrelation function of depolarized light scattering intensity coincides with the time dependence of relaxation of scattered light intensity alteration after the electric field which induced particle orientation is switched off. This allows to use dynamic light scattering technique during the study of electro-optical properties of polydisperse colloids of diamond.