The Argentium Revolution

Read about the science behind Argentium’s superior tarnish resistance properties, and learn about Argentium International’s standardization protocol.

Last edited: 10/30/2019

Argentium® Silver has undergone many changes since the advantages of adding germanium to a basic sterling silver alloy were first discovered by Peter Johns at Middlesex University, more than 20 years ago.

Left: Torch annealing silver Right: Firestain on traditional sterling silver.

Peter was astonished at how the addition of germanium prevented firestain. The additional benefit of superior tarnish resistance became apparent when samples of different development alloys (stored in the same safe as traditional sterling silver) remained bright and shiny, whereas the traditional sterling discolored. When Peter told us of how he noticed the improved tarnish resistance, we immediately thought of the way in which Harry Brearley discovered stainless steels—as part of his investigation into new gun-barrel materials he observed that some experimental steel compositions had exceptional resistance to corrosion.

Since Brearley's discovery stainless steels have been studied intensively over the years to better understand and optimize their properties. With the same aims, Argentium International has also implemented a continuous research and development program to better understand the properties of Argentium® silver alloys and to learn how to optimize these properties for different applications. These investigations have included some advanced work using electron microscopy techniques that look closely at the formation of the protective germanium oxide layer on the surface that gives Argentium silver alloys their unique properties.

Argentium grain enlarged
Argentium grain enlarged
This photograph shows the grain structure revealed when tunneling down through the surface of Argentium® silver using an electron microscopy technique known as "focused ion beam" (FIB).

This is the same section enlarged. A platinum layer was applied to the surface before tunneling to protect the surface features. This section clearly shows the protective germanium oxide layer present at the surface, which covers both the copper-germanium rich and the silver rich phases that are present in Argentium® silver alloys.

Those of you who have used Argentium® silver for many years may remember some of its earlier names such as "College Silver" or "Bright Sterling Silver." The name "Argentium" was later chosen to describe these highly tarnish resistant silver alloys. Testing criteria has been put in place to ensure the silver alloys qualify as Argentium (more on this Argentium qualification standard in another post).

In the past, some of you may have used different alloy grades of Argentium® silver such as 925, 930, 970, or even 945. As a result of recent research to best optimize the properties of the alloys together with a testing program working with our major partners (including Rio Grande), we have ensured that the improvements made maintain and surpass the properties and abilities that you have come to expect from Argentium silver. We have now rationalized our alloy naming and designations so that it is the same worldwide—the Argentium alloys currently available are:

Argentium Table

The Argentium® 935 grades exceed the requirements of sterling silver hallmarking standards and the Argentium 960 grades meet the requirements of the historic Britannia silver standard that is recognized by the United Kingdom Assay Offices (these alloys must have a minimum pure silver content of 95.84%).

One other important aspect of Argentium® silver production to note is all of Rio Grande's silver is sourced from recycled material, and we have traceability of that silver back to the refinery. We know that sustainability and ethical manufacturing are becoming increasingly important to our customers and we hope that the measures that we have put in place reflect these concerns.