The micro-chemical structure of silver- or gold-plated objects dating back to the Greek, Roman, Barbarian and Dark Age periods has been studied in order to identify the different plating techniques used. Attention has been focused on coins and luxury objects such as jewels, buckles and decorative items. The results indicate that several methods were used in ancient times, some of them very complex and sophisticated. Furthermore, the results obtained from the study of the golden altar of Saint Ambrogio (825 AD) in Milan, considered one of the most important goldsmith’s work ever made, are presented. The altar consists of large panels of gold and gold plate and is set with different gems such as emerald, topaz, amethyst, agate and carnelian. This work of art was gold-plated by coating the silver surface with a gold/mercury paste and then evaporating the mercury by heating to about 300°C.

Authors: Dr. G.M. Ingo, Tilde de Caro, Maurizio Marabelli, Pino Guida, Giuseppe Bultrini