Examples of sterling silver symbols include 925 or .925, .999 and .813. Other examples of symbols on sterling silver include a lion, a crown, initials or the word "sterling."
When numbers are engraved into sterling silver, they denote the purity of the metal. The purest form of silver is 99.9 percent, and the accompanying marker is 99.9. The 925 or .925 mark, indicating 92.5 percent purity, is one of the most common markings. The .813 marker for 81.3 percent purity is also very common.
The word "sterling" alone also denotes a pure form of the metal. If other words accompany it, though, the purity is likely not as high.
Sterling silver often features other symbols, which are called hallmarks. For example, a lion denotes that a piece is British sterling. In fact, the lion stamp has changed through the years, so it can indicate the age of a piece. Another common symbol that denotes the age of a piece is the head of the reigning monarch of the time.
British cities often used their own symbols as hallmarks. For example, an anchor designates the silver came from Birmingham, while a crown stands for Sheffield.
Silversmiths also use hallmarks to designate their handiwork. Previously, they used animal symbols to suggest the family name. Today, it's more common for a silversmith to use initials or the family name itself.