Goldanalytix GoldScreenSensor Mode D'emploi page 27

 Scratches
 Blisters & capsules / other packaging
 Temperature effects (different temperatures of device and test object)
 Embossing on coins or bars
 Bends / deformations
 Uncommon coins or impurities with ferromagnetic material
IMPORTANT: A correct conductivity value alone is of course no guarantee that your object is not
a fake. After all, an alloy that has, for example the same electrical conductivity as gold, can
definitely be produced (e.g. copper alloys). However, in such a case the dimensions or weight of
the coins o bars is usually not correct. After all, it is relatively easy to imitate one physical
property (conductivity, density, sound, etc.) of a precious metal. To imitate two or more physical
properties at the same time, however, is more difficult or almost impossible. Therefore, for the
same conductivity, another physical property such as the density does not match. We therefore
strongly recommend the use of several testing methods in order to exclude counterfeits with
certainty. This is because no single non-destructive method for testing precious metals can on
its own detect any kind of counterfeit.
For coins, the following procedure is recommended:
Step 1: Determine the weight with the help of a precision balance – does the determined weight
correspond to the target weight? In many cases, fakes can already be detected in this step.
Step 2: Compare the dimensions (thickness & diameter) with the nominal values of the
respective coins with the help of a digital caliper (can be purchased for a reasonable price in our
online shop or at specialist shops) or stencils.
If 1 and 2 correspond exactly to the nominal values (can be found on the internet, e.g. on the
websites of the manufacturers), it can only be a counterfeit with materials of the same density –
these are for example metals like tungsten or uranium for fine gold or for silver, for example,
lead-tin alloys or molybdenum .
Step 3: Detection of sub-alloys and counterfeits made of e.g. molybdenum, tantalum or
tungsten, tungsten alloys, tungsten carbide, brass, copper, etc. up to a penetration depth of
about 250 µm (for fine silver) over 350 µm (fine gold) up to 650 µm (Gold 916, e.g. Krugerrand)
with the GoldScreenSensor.
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. 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.
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