X-ray irradiation was applied to control the size of metal colloids in a silicate glass to make a high precise photosensitive glass containing K2O, Na2O, ZnO BaO, 0.01-0.05wt.% Au metal as sensitizer, <1.2wt.% Sb2O3 and SnO2 as thermal reducer. Colorimetry showed that X-ray irradiation effectively works to make the color of red system. Transmission electron microscopy revealed that the metal colloids were oxided and had uniform and spherical shape of 10-20 nm. Au colloid made various colors like pink after heating at 400°C, red at 500°C and dark-red at 600°C. Ag colloid made them like yellow-green at 400°C, yellow at 500°C and dark-brown, respectively.