Reference and comparison values for conductivity and density

On this page we provide you with reference and comparative conductivity values for the GoldScreenSensor, the GoldScreenPen and the DensityScreenScale. This allows you to quickly and easily check whether a certain metal shows the expected electrical conductivity in MS/m (megasiemens per meter) or the correct density in g/cm³ (gramm per cubic centimeters). Please note: The electrical conductivity depends heavily on the temperature. All values given are based on room temperature (20 ° C).

The following is an overview of the most important alloys that are used for precious metal coins and bars. Plus an extensive selection of examples for each of the alloy and metal types.

Target values for investment precious metal alloys

Target values for smaller objects on the GoldScreenSensor

Target values for other metals

Here you can find an additional overview for the conductivity values of the most frequently used counterfeit materials for gold, silver, platinum and palladium.

Important information on older coins and precious metals (defined here as before 1945)

Older coins / bars (defined here as coins / precious metals before World War II) and especially pieces from the 19th century may vary in their composition. This means that the gold content may be correct, but the rest of the composition is different for some coins. For example, 900 gold coins should actually consist of 900 parts gold and 100 parts copper - but due to the manufacturing and analysis conditions that were sometimes not optimal at the time, it can of course happen that such coins were contaminated with other metals and thus change the conductance for the coin. Furthermore, the gold used was often not always 100% pure and when it has been melted, impurities got into the final alloy. For example, during these times (around 1800 and later), gold was still won on various raids or other expeditions. Please note: We can only specify the nominal values for the correctly manufactured coins (i.e. mostly the precious metal-copper alloy, sometimes nickel). The range of possible contamination and its effects are impossible to understand in their entirety. In our tests, however, we uncovered that, for example, Vrenelis 20 CHF sometimes had 10 to 20 times the iron content of their cleanly produced "colleagues" from the same vintages. The gold content of all coins was exactly as it should be (90% gold content), however, in addition to copper and silver, some of the coins also had a significantly higher iron content using X-ray fluorescence analysis.

This means that with the Vreneli from 1922 one can safely say that some coins were minted uncleanly or that additives to the gold were not just pure copper. Since the GoldScreenSensor is a very precise eddy current measuring device, such impurities are of course also recognized and then lead to lower conductance values (iron lowers the conductance value in such alloys relatively strongly) in the conductivity information. In summary, such cases are therefore not counterfeits, but only improperly crafted “variants” of the real coins, often with ferromagnetic contamination (iron or nickel). It is therefore essential to use other test methods for such coins (e.g. density test or superficial test with acids or XRF) in order to distinguish whether it is actually an alloy (which of course also often occurs) or "only" one of the cases described above. A 900 gold coin remains of course 900 gold, even if instead of the remaining 100 parts copper 98 parts copper + 2 parts iron are present. The gold content is therefore not reduced by such an impurity. The conductance can however change, making it more difficult to interpret the results.