when did they start using 925 on silver
Silver hallmarks In the early United States, no national assaying system was adopted, although the city of Baltimore did maintain its own assay office between 1814 and 1830.[citation needed] Prior to the general adoption of sterling silver as the standard of purity in 1868, silver was generally obtained from the melting of coins. Since these could vary considerably in purity, from around .750 millesimal fineness to around .900, silver known as "coin silver" varies in purity. Silver at that time was sometimes marked "COIN" or "PURE COIN", but can also be without a standard mark altogether. After the adoption of the sterling standard, pieces were marked with "STERLING", the number "925" or the notation "925/1000".[citation needed]
Group 11 element Group 11, by modern IUPAC numbering,[1] is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold. Group 11 is also known as the coinage metals, due to their former usage. They were most likely the first three elements discovered.[2] Copper, silver, and gold all occur naturally in elemental form.