X-RAY FLUORESCENCE STUDY OF ALLOYS CONTAINING GOLD AND SILVER

Abstract

This paper presents the results of a comprehensive study of the chemical composition of alloys containing gold and silver, as well as other metals, using the modern non-destructive X-ray fluorescence (XRF) analysis method. The relevance of the research is determined by the need for quality control of precious metals in the jewellery market, where deviations from declared standards are often encountered. The aim of the work was to identify and analyze the actual composition of jewellery, medals, and coins from various historical periods and origins. For the study, an ElvaX spectrometer was used to perform quantitative and qualitative analysis of the alloys. During the analysis of gold jewellery, it was found that the fineness of most of the analyzed samples did not correspond to the hallmark. Specifically, in modern 585-fineness items, the gold content ranged from 58.14–58.55 %, which for some items is below the minimum permissible standard. It was discovered that to cheapen the alloys, silver in the ligature is often replaced with zinc, which is significantly cheaper. Additionally, an undesirable impurity of nickel, a potential allergen, was found in one of the samples. The analysis of silver items also showed significant deviations: the silver content in some samples was lower than the declared 925 fineness, while in others it significantly exceeded it. The study of gold and silver medals and coins confirmed the historical features of their production. For example, a gold coin from the time of Nicholas II (sample 12) almost perfectly matches the declared 900 fineness, while silver «poltinniks» (samples 14, 15) have an inflated silver content. The analysis of modern coins from the European Union, Ukraine, and Poland confirmed the use of specialized alloys such as Neusilber and Nordic Gold, which is consistent with known minting technologies. The results confirm that the XRF method is a reliable tool for quick and effective control of the composition of metal products, allowing for the detection of inconsistencies and falsifications, which is particularly important for both expert institutions and consumers. Overall, the conducted analysis demonstrates the high effectiveness of XRF for expert examination.