Silver and sterling silver alloys

Sterling Silver

Sterling silver most commonly refers to silver that is 92.5% pure silver with 7.5% alloy. The most common alloy used to create sterling silver is copper.

Silver is alloyed for the same reason as gold and platinum. As a pure metal, silver is generally too soft to be used in applications where daily wear with damage the metal. Primarily this affects jewelry, silver ware, and other household items.

Argentium Sterling Silver

One of the new alloys being used to create sterling silver is argentium.

Technical Specs:

Argentium sterling silver was developed by Peter Johns and patented, (Patent Nos. US 6,168,071, GB 2255348, GB 2283934 and European Patent No. 0729398.), in 2001. Argentium contains, approximately, 92.5% silver, 6.3% copper, 1.2% germanium, and trace amounts of boron. Argentium sterling silver is also slightly lighter than copper alloyed sterling. Pure silver has a specific gravity of 10.49, copper based sterling silver has a specific gravity 10.36 and argentium sterling silver has a specific gravity of 10.30.

Benefits:

The primary purpose of the germanium in the alloy is that it greatly reduces the effects of tarnishing over time. Most silver products will develop an oxidation layer on them as time passes. This is usually easily wiped off or removed with a chemical. Argentium sterling helps counteract the effects of oxidation keeping jewelry and silver pieces looking bright and clean longer.

A secondary benefit to argentium sterling silver is that it reduces fire scale. During the manufacturing process the metals are heating to their melting point for casting. This high heat produces a surface condition known as fire scale. This is a reddish color or stain that appears on silver/copper alloys when heating in the presence of oxygen. It is caused by oxygen combining with copper during the casting process.

By using less copper, and reducing the melting point slightly, the effects of fire scale are greatly reduced. This, in turn, reduces the amount of clean up needed after the piece is cast to return it to a bright white color.