GOLDANALYTIX GOLDSCREENSENSOR Bedienungsanleitung Seite 66

Alloy impurities:
The range of possible impurities and their consequences are impossible to be comprehended
entirely. However, in our tests we found that Vrenelis 20 CHF, for example, sometimes had 10 to
20 times the iron content of cleanly produced Vrenelis of the same year. The gold content was
correct in all of those coins (90% gold content), but in some coins, XRF-analysis detected a much
higher iron content, in addition to copper. This indicates that some Vreneli coins from 1922 were
minted improperly and do not contain only pure copper in addition to gold. Since the
GoldScreenSensor is a very precise eddy current measuring device, such impurities are detected
and lead to lower conductivity values for the measured coins: iron lowers the conductivity value
in such alloys relatively strong. In conclusion, such coins are not to be considered as counterfeits,
but merely as unclean variations of real coins, which often have a ferromagnetic contamination
(iron or nickel). It is therefore essential to combine more testing methods for such coins (e.g.
density testing or superficial testing with acids or XRF) in order to distinguish whether the coin is
indeed a fake of just one of the cases described above. A .900 gold coin remains a .900 gold coin,
even if instead of the remaining 100 parts of copper there are, for example, 98 parts of copper +
2 parts of iron. The conductivity value can change, however, which makes the interpretation of
the results more difficult.
Penetration depth of the GoldScreenSensor:
Depending on the conductivity of the material, the GoldScreenSensor penetrates the respective
metals or alloys to different depths. With highly conductive materials such as silver [61 MS/m],
the device penetrates less deeply than with alloys from the medium (gold 999 [45 MS/m] or gold
986 [approx. 25.5 MS/m]) and low conductivity range (e. g. Krugerrand [9.7 MS/m]). For silver,
one can expect a penetration depth of about 250 µm (0.25 mm), whereas for the Krugerrand
alloy penetration depths are up to 650 µm (0.65 mm). This is quite a lot, considering that most
gold- or silver-plated layers are only 10 to 60 µm thick. The penetration depth of the
GoldScreenSensor determines the size up to which precious metal objects can be measured. In
principle, you can also measure 1 kg silver ingots with the device - there will be a conductivity
value. However, with such large objects, there is a risk that the forgers apply thicker layers of
precious metal around the fake metal core. In the case of precious metal layers that are thicker
than the respective penetration depths, the GoldScreenSensor no longer provides a valid result.
Therefore, one should always combine several suitable testing methods, especially for objects
over 1 ounce. For bars from approx. 50 g, we recommend the additional use of the ultrasonic
method (Goldanalytix BarScreenSensor). For objects up to 1 ounce, however, the penetration
depth is sufficiently high to detect counterfeits.
General information:
In the measurement mode, the device always displays the measured conductivity value, as well
as the material that it MIGHT be. A 50 Euro cent coin, for instance, has a similar conductivity as
Krugerrand Gold (alloy 916(A)), platinum or palladium. When measuring the 50 cent coin, the
GoldScreenSensor can therefore output Gold 916 as the measurement result, even if it is not the
alloy in question. If one compares dimensions and weight, it quickly becomes clear that this is
not a Krugerrand.
5