What is sterling silver?
Sterling silver is an alloy of 92.5% pure silver and 7.5% copper. The added copper makes the silver strong. Pure silver is very soft. It is too soft to use in jewellery, so instead sterling silver is used. Sterling silver is also called first grade silver and silver 925. Sterling silver jewellery is hallmarked with a “925” stamp.
With sterling silver being first grade silver, there is also second and third grade silver. Second grade silver is hallmarked with an “835” stamp, meaning it is an alloy of 83,5% pure silver and 16,5% copper. This is also used in jewellery, but gives a dark silver colour. Third grade silver is hallmarked with an “800” stamp, meaning it is an alloy of 80% pure silver and 20% copper. This silver alloy is mostly only used in utensils.
Pure silver has a millesimal fineness of 999, meaning it contains 99.9% silver. It is also called fine silver or silver 999. The 0.01% other materials in silver 999 are naturally occurring tiny amounts of impurities. Fine silver is used to make bullion bars (ingots) and coins for trading and investment in silver.
It might be a bit confusing, because jewellery made out of sterling silver does belong in the category of fine jewellery together with jewellery made out of gold, platinum and other precious metals.