A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (lambda = 1064 nm), second (lambda(SHG) = 532) and third (lambda(THG) = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by lambda(irrad) = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs. (C) 2013 Elsevier B.V. All rights reserved.