Gold nanoparticles were precipitated inside gold ion-doped glasses after irradiation by a femtosecond laser, a nanosecond laser or X-ray and successive annealing. Experimental results show that the irradiation resulted in decrease of minimum annealing temperature and critical size for the precipitation of gold nanoparticles. The observed phenomenon has promising applications for the fabrication of multi-colored images inside transparent materials, optical memory and integrated micro-optical switches. (C) 2004 Elsevier B.V. All rights reserved.