This article reports the effect of Ag+ ion-exchange on the precipitation of PbS quantum dots (QDs) in silicate glasses. The glasses were subjected to ion-exchange in AgNO3 salt melts at 260 degrees C for 60 s. Ag nanoparticles (NPs) and PbS QDs precipitated after heat treatment at temperatures of 440 degrees C 460 degrees C for 10 h. Photoluminescence wavelength lambda PL of PbS QDs was longer (similar to 1525 = lambda PL = 1580 nm) in Ag+ ion-exchanged regions than in Ag+-free regions (similar to 1030 = lambda PL = 1200 nm). Average diameter D of PbS QDs estimated by calculation and TEM images was larger in Ag+ ion-exchanged regions (similar to 5.2 <= D <= similar to 5.5 nm) than in Ag+-free regions (similar to 2.4 <= D <= similar to 3.3 nm). Ag NPs that formed during heat treatment provided the sites for heterogeneous nucleation of PbS QDs and promoted the precipitation of PbS QDs in glasses.