The 0.91-gram silver coin shown in the image dates back to the era of Sigismund II Augustus (Zygmunt August)—King of Poland and Grand Duke of Lithuania (1544–1572)—most likely to the 1550s or 1560s. Diameter: Between 19.0 mm and 20.0 mm (as it was hand-struck during that period, slight shifts or minor irregularities in shape—such as a slightly elliptical form—may be visible along the edges). Thickness: Approximately 0.5 mm – 0.55 mm (it has a very thin, wafer-like structure). Weight: Ranges from an average of 0.80 grams to 1.25 grams; depending on the year of minting and mint efficiency, it can rarely reach up to 1.54 grams.(5 magnificent, valuable antique coins)