Abstract

A new application of laser-induced breakdown spectrometry (LIBS) in the jewellery industry, namely the determination of the layer thickness and composition of gold-plated pieces, is reported. It consists of subjecting the piece to a number of laser shots, monitoring the emission lines of the elements present in the sample layer and calculating the depth profile of the sample as the laser beam passes through it. The method was designed for the determination of the thickness of the gold layer in gold-plated pieces, thus avoiding fraud in this area. In addition, the method provides information about both the composition of the deposited layer, mainly gold concentration, and the composition of the alloy used to fabricate the piece. The latter information is achieved by increasing the shot number to surpass the gold–base alloy interface.