An atypical interlaboratory assay: looking for an updated hallmark (-jewelry) method

A comparison between a laser-induced breakdown spectrometry-partial least squares (LIBS-PLS) method and methods based on some well-known techniques, such as induced-coupled plasma-atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (FAAS), and atomic scanning microscopy (ASM) is presented in order to both validate the content of gold and silver in alloys to be used as solid standards and develop an alternative to the established methods for the hallmark of gold and silver in jewelry pieces. 17 alloys with gold concentrations ranging from 100 to 50% and 8 alloys with silver concentrations between 100 and 80% and variable concentrations of other metals usually present in jewels were used as solid standards in LIBS in order to develop a method as general as possible. The results obtained in the analysis of some alloys (9 for gold and 7 for silver) show that the proposed method is comparable with the official one.