Silicon ions were implanted into fused silica substrates at doses of 1×1021, 2×1021, 5×1021, and 1×1022 ions/cm3. The implanted substrates were annealed at 1100°C for one hour in a reducing atmosphere (95% Ar+5% H2). Optical absorption spectra recorded after the annealing treatment showed absorption onsets at 3.86, 3.73, 2.86 and 2.52 eV for substrates implanted with 1×1021, 2×1021, 5×1021, and 1×1022 ions/cm3, respectively. Static photoluminescence (PL) measurements indicated red emission between 1.72 and 1.61 nm with a slightly increasing red shift with ion dose. Time resolved PL at room temperature revealed slow (∼50 μs) and fast (×20 μs) lifetimes which increased with decreasing temperature. TEM studies showed that the particle size increased with increasing ion dose. Typical particle sizes ranged between 2 and 5 nm indicating quantum confinement of the exciton, which can account for the blue shift in the absorption edge with decreasing ion dose. However, the maxima in the PL spectra for all ion doses are relatively independent of the ion dose and are strongly shifted from the absorption spectra. This suggests that radiative recombination occurs from a common luminescent center, possibly a surface or interfacial state in thexs SiOx, layer surrounding the nanocrystal.