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Hallmarks are printed numbers on silver that are used to verify whether silver is genuine. Both pure silver and sterling silver are forms of genuine silver; however, pure silver is a higher grade than sterling silver, therefore featuring a different hallmark. There are standard hallmarks used in the United States, although a variety of hallmarks can be found throughout the world.

Millesimal Fineness System

The millesimal fineness system determines parts per thousand of an alloy, therefore determining how pure an alloy is. Alloys are two metals that are mixed together to form a specific strength. Common metals in jewelry alloys include silver, gold and platinum. The percentage of silver in an alloy determines how pure it is. For example, if an alloy contains only 30 percent silver, it is not a high enough percentage to be considered either sterling or pure silver.

Pure Silver

According to the millesimal fineness system, an alloy must consist of 99.9 percent silver to be considered pure or fine silver. Items that are pure silver are marked with the hallmark of ".999" or "999." This hallmark can often be found on the inside or underside of an item. Pure silver is soft and breakable; therefore, it is not used often in jewelry.

Sterling Silver

Sterling silver is a commonly used in jewelry for its strength. Sterling silver is a combination of silver and copper. According to the millesimal fineness system, sterling silver is 92.5 percent silver and 7.5 percent copper. Therefore, the hallmark found on sterling silver items is either ".925" or "925." Sterling silver is also known as standard silver. On necklaces, this hallmark is often found on the clasps. On rings, the hallmark is often found on the inside of the ring.

Silver Hallmarks Around the World

While "925" and "999" are the American standards for sterling and pure silver hallmarks, there are additional hallmarks used around the world to mark the authenticity of silver. If you have a piece of antique jewelry that is older than 150 years or you own jewelry purchased from another country, it may contain one of the following numbers, all of which indicate the silver is either sterling or pure: 1000, 999, 980, 970, 959, 958, 950, 948, 940, 935, 934, 930, 925, 916, 915, 900, 875, 844, 840, 835, 833, 830, 826, 813, 800, 750, 700, 687, 625 or 600.