Silver is a chemical element, numbered 47 on the Periodic Table, and is one of the classical precious metals, along with gold and platinum. It has been used for millennia in creating fine jewelry, art, and as currency. In nature, it is usually alloyed with ores of copper, copper-nickel, or lead, and it is then separated out and purified. Most fine silver is at least 99.9% pure, and extremely high-grade metal is upwards of 99.999% pure. Sterling silver, on the other hand, has other metals added, usually around 7.5% copper.
While true fine silver is a beautiful metal, and makes an ideal material for jewelry and fine art, it is far too soft to be of much use for functional items. However, because of its value and prestige, many people wish to make functional items out of it, especially things like flatware or serving platters. Sterling silver takes the beauty and best qualities of fine silver, but adds the durability of a stronger metal. The majority of sterling uses copper as the alloy metal, as it is readily available, strong, and doesn’t change the color very much.
Pure silver is an almost perfect metal from an aesthetic perspective. Because it is almost entirely non-reactive, it doesn’t tarnish or corrode over time, even in the worst of environments. This makes it ideal for jewelry and fine art purposes, since they will retain their shine. Sulfur does tend to create tarnish, and so most polishes are specifically formulated to remove silver sulfide. For the most part, however, the pure metal is free from dangers of tarnishing.
As it becomes less pure, however, the problem of tarnishing becomes greater. So sterling silver, while more durable, is also more prone to discoloration over time. Sodium chloride, common table salt, reacts with copper-silver sterling, for example, which can often be seen in sterling salt shakers, which over time will corrode. Other, non-copper, metals may be used to create sterling silver that is less reactive and less prone to tarnishing or corrosion, but so far no perfect match has been found.
In recent years, however, a number of companies have begun experimenting widely with different metals, each with their own beneficial properties. Some of the more promising metals used in sterling include zinc, platinum, and germanium. Some other additives, notably boron and silicon, have also been added to certain formulations of sterling silver to try to prevent corrosion. Argentium sterling is probably the most famous of the newer varieties, using a mix of germanium and copper in addition to the 92.5% silver. This alloy is known for being extremely resistant to tarnishing, and the lack of the coloration known as firescale.
Sterling silver products are generally branded with what is called a hallmark. This hallmark gives an indication of the purity, as well as what other metals may be used in it. It may also note when and where the sterling was produced, and who the silversmith that made it was.