Argentium silver (originally patented in 1998) is a brand of modern tarnish-resistant silver alloys, containing either 93.5% or 96% silver. Argentium alloys replace some of the copper (approximately 1% of the copper and other alloys is replaced with germanium) in the traditional sterling silver alloy (92.5% silver + 7.5% copper) with the metalloid germanium. Argentium's patents refer to percentages of zinc and boron present in Argentium silver. Both Argentium alloys exceed the standard required for hallmarking as sterling silver and Argentium silver 960 meets the standard for hallmarking as Britannia silver (95.84% silver).
Argentium silver is the result of research by Peter Johns at the Art and Design Research Institute (ADRI), School of Art & Design, Middlesex University. The project began in 1990 with research on the effects of germanium additions to silver alloys. Germanium was discovered to impart the following properties to sterling silver:
Many of these properties significantly affect the traditional methods of working silver. For instance the absence of firescale eliminates tedious and time-consuming steps required by the silver worker using traditional sterling silver. It also eliminates the need for plating the final product which is often done on manufactured items because of the problems introduced by firescale. Tarnish resistance is of significant importance to both silver workers and the wearer of silver jewellery.
Argentium Silver is patented and trademarked by Argentium Silver Company, UK.
Traditional sterling silver has a solidus melting temperature of 802°C (1475°F) and a liquidus flow point of 899°C (1650°F). Argentium 935 silver has a solidus of 803°C (1477°F) and a liquidus of 903°C (1657°F), while Argentium 960 has a solidus of 905°C (1661°F) and a liquidus of 925°C (1697°F).