About “traditional” sterling silver
Sterling silver, or .925 sterling silver, is an alloy of 92.5 percent silver mixed with another metal (usually copper). Adding another metal to the pure, or “fine”, silver makes it harder and better able to stand up to wear; however, it also makes it tarnish easily.
How is Argentium silver different?
Argentium silver is a relatively new alloy of silver, that actualy has a higher content of pure silver (Argentium comes in .935 and .960 grades), but it replaces part of the copper in the alloy mix with germanium. For reasons having to do with the way germanium reacts with oxygen, Argentium silver is far more tarnish-resistant than regular sterling silver. The exact formulation of Argentium silver is patented by, and the name itself is trademarked by, the Argentium Silver Company.
On top of this fantastic superiour purity and tarnish-resistance, Argentium Silver is certified as being made from 100% recycled silver, so it’s much more environmentally friendly. I just love this stuff! Many of my designs (in particular, the hand stamped designs) are made using Argentium silver.
If you would like to know more about Argentium silver, Wikipedia has a good reference article.