Sterling Silver is an alloy of silver which contains 92.5 % mass of silver and 7.5% by mass of copper. The Standard of Sterling Silver has a minimum millesimal fineness of 925.
What is Sterling Silver 925?
99,9 % Pure Silver is called Fine Silver which is too soft to produce functional objects. For instance, Pure silver cannot be used in making jewelry as it is extremely malleable and it can suffer damage easily. So the Silver is mixed with another alloy usually Copper to have a strength. It also tends to get very soft, even in conditions of normal temperature. That is why 925 silver is used and not the pure form of the precious metal. So the Silver is mixed with another alloy usually Copper to have a strength. By this way, Silver preserves its ductility and the beauty of the precious metal.
By adding copper to silver, craftsmen have managed to obtain a highly reliable alloy that is successfully used in the jewelry industry. The combination is very popular as the silver craftsmen can make earrings, rigs, bracelets and other pieces of silver jewelry, knowing that their work will be resistant and durable.
In many countries the hallmark 925 represents the quality of Silver, it means the jewelry you buy is with highest silver quality.