To identify the signs that distinguish natural diamonds from artificial diamonds, a comparative analysis of the luminescence spectra with regards to the Q factor, center of gravity, bandwidth parameter, and energy losses in the diamond crystal lattice under conditions of ohmic and dielectric relaxation of luminescence is performed. The phenomenon of resonant luminescence in the femtosecond time range is detected in diamond. It is established that natural and artificial diamonds noticeably differ in the relaxation frequency and in the energy of resonant radiation.

It is experimentally established that the luminescence spectrum of diamond at room temperature contains one or two peaks in the form of Gauss curves. This result is related to the exciton-phonon interaction in diamond, which, along with the zero-phonon line, contains first and second order phonon repetitions. This phenomenon is typical only for natural diamonds and is absent in synthetic samples. Therefore, it can be used to identify cut diamonds (diamonds).