Nanoscaled Y3Al5O12:Ce (YAG:Ce) particles prepared through a coprecipitation method and heated to elevated temperatures were treated in different weights with tetraethyl orthosilicate at room temperature for surface coating. The IR absorption measurements attested to the presence of silica in YAG:Ce by a broad absorption band at 1000-1400 cm-1, while maintaining a cubic structure and constant lattice parameters as revealed from the X-ray diffraction analysis. Transmission electron micrographs also presented the encapsulation of YAG:Ce nanoparticles in silica as the IR results. The optical properties of photoluminescence (PL) of these silica-coated YAG:Ce were found to depend on the quantity of YAG:Ce nanoparticles in the coating solution with an optimal weight ratio of 0.16 (silica/YAG:Ce). The increased PL intensity of these YAG:Ce after silica coating was proposed to result from the quenching inhibition of surface states in YAG:Ce nanoparticles and the increased light extraction from the silica/YAG:Ce interface.