About sterling silver
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.
Fine silver, for example 99.9% pure silver, is generally too soft for producing functional objects; therefore, the silver is usually alloyed with copper to give it strength while preserving the ductility and appearance of the precious metal. Other metals can replace the copper, usually with the intention of improving various properties of the basic sterling alloy such as reducing casting porosity and increasing resistance to tarnish. These replacement metals include germanium, zinc and platinum, as well as a variety of other additives, including silicon and boron. Alloys such as argentium silver have appeared in recent decades.
Many sterling silver rings are manually tarnished, or darkened, to bring out the detail in the design. Also known as contrasting, this is usually done by applying Liver of Sulfur. Please note that some contrasted rings might change the color of your skin at first, due to the contact of skin with the darkening compound.