Population trapping in the ground state spin sublevels of Cr3+ in ruby at liquid helium temperature is considered. It is proposed to excite the R-1-transition by a bichromatic laser beam with an optical frequency difference matching the ground state spin sublevels splitting. If the excitation is strong enough to decouple Cr3+ from its environment, responsible for dephasing, an appreciable amount of the population is trapped in a particular superposition of the spin sublevels. This superposition state does not interact with the laser beam because of the destructive interference of the quantum paths constituting the transition. Population trapping can be detected by the reduced luminescence from the excited state and by the magnetization ringing originating from the ground state spin coherence.