Pure silver is bright white in color and is the most reflective of the precious metals. Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925. As it is relatively soft and scratches easily, it is standard practice to alloy pure silver with harder metals to improve its strength. Sterling silver is the world’s most popular silver alloy. To be classed as sterling silver, the alloy must contain at least 92.5% pure silver. The remaining 7.5% can be made up of other metals, most commonly copper.
Sterling silver is highly regarded for jewelry use as it preserves the color, luster and mass of pure silver and also significantly improves the metal’s durability, making it more resistant to wear and tear. When 92.5% of pure silver is mixed with 7.5% of other metals (often copper, nickel or zinc) the resulting alloy is called sterling silver. To identify it as such, the number 925 is stamped upon the silver, often in a hidden part of the jewelry. This number is known as the hallmark and denotes the percentage of silver purity in the alloy. In other words, 925 is the same as sterling silver, meaning that if there is any other stamp on the metal, it is not sterling silver.