Yttrium aluminum garnet (YAG) crystals grown by Czochralski (CZ) and temperature gradient technique (TGT) methods, were irradiated by gamma-rays and excimer laser. Same results were obtained after different irradiations. Absorption peak at 255 nm disappeared and a new broad peak at 370 nm appeared in CZ grown YAG crystals after irradiation. Weak luminescence centering at 404 nm was found after excitation at 370 nm. All results indicated that F-type color centers were formed and Fe3+ ions changed to Fe2+ ions in the CZ grown YAG crystals. Absorption spectrum of TGT grown YAG crystals did not change and no luminescence of color center was found after both irradiations. (C) 2003 Elsevier B.V. All rights reserved.