The physicochemical analyzes of silver lunula from the early medieval treasury conducted by NCBJ allowed to establish the techniques of soldering necklaces ornaments. Due to the good condition of the monuments, it was possible to examine their surface for soldering residues, which are often removed by a poorly carried out conservation process. The research shows that the main components of the solders were copper compounds, with the addition of resin glue and lead oxide – a component of the solder mixture described in the historical goldsmithing guide – in the 10th Papyrus of Leiden. Lead may come from Upper Silesian deposits, which, according to the available data, were not exploited until the 11th century. The dating of the use of these deposits using isotope analyzes of silver from the treasures is still continued by researchers.