The paper presents the results of historical analyzes, optical microscopy and XRF spectrometry applied in the field of numismatics, characterizing some Romanian coins from the XIX–XX centuries. The archaeometric characteristics specific to the raw material and to the corrosion products generated during both the use and the demonetization period were established, under the action of natural factors. The study was based on the analysis of 15 Romanian coins representing issues during the reign of Romania under the leadership of King Carol I, 1881–1914, made of a binary or ternary alloy based on silver. At present, these monetary issues are little studied in terms of the nature of the alloy and the raw material used as well as the degradation of silver that occurs between the first and last issue. The major element, Ag, has been used to track changes in alloys over time. An important role in coin authentication is also the knowledge of the manufacturing techniques, the characteristics of the edition and the range of use.