Single crystals of gallium-gadolinium garnet (GGG) irradiated by fluences of fast neutrons (0 to 3.8 x 10(24) m-2) are investigated by X-ray and magnetic methods. It is found that irradiation with high fluences leads to complete amorphization of the samples. Besides, the samples recover their single crystalline structure under subsequent thermal annealing (excluding the surface layer). It is shown that on amorphization the absolute value of the paramagnetic Curie temperature increases by a factor almost-equal-to 2.