In order to improve the luminance of red emission of the (Y,Gd)BO3:Eu3+ phosphors were coated with SiO2 nano particles. It was revealed that the surface coating of phosphors with SiO2 leads to an increase in luminance intensity. This seems to be due to the increase of the excitation light which is transmitted into the phosphor, i.e., an effective vacuum ultraviolet absorption of the phosphor via SiO2 nano particles. The experimental results suggest that the surface coating of phosphors with SiO2 nano particles is a way to improve the luminance.