Since the gold price has risen sharply in recent years, counterfeits of gold bars or manipulated gold bars are increasingly appearing on the market. These are either gilded bars with a core of tungsten or other base metals, or real gold bars, which have been hollowed out and filled with base metals / metal alloys. In order to be able to recognize such counterfeits when purchasing gold bars, some technical tools are required:
Scales / Hydrostatic Scales
Sliding / measuring tools
X-ray fluorescence devices RFA
Check the bars and check for plausibility
First, the bar to be checked should be subjected to visual inspection.
Is the preform and the surface identical to the known ingots of the upmarket manufacturer?
In bars with serial number, counterfeits e.g.
However, there are also bogged bars on the market, which are certificated with certificates and which are different for each counterfeit on the bar as well as on the certificate of approved serial numbers. For these, e.g. 1g-Argor-Heraeus-Barren counterfeits are professionally mass-produced fraud bars. Optically very well-made counterfeit Kinebar gold bars are now also on the market.
Each ingot should be weighed individually to determine whether the single-pointed weight matches the actual ingot weight.
In many counterfeits or pattern bars made for shop window decorating purposes, the actual weight to the punctured weight varies. If the weight deviates from the permissible tolerances, the bar is incorrect or manipulated.
If the weight is correct, it must be checked whether the dimensions of the ingot are correspondingly plausible in relation to the specific weight of the respective precious metal. For this purpose, the ingot can either be measured and a desired weight for the ingot can be calculated by means of the calculated volume multiplied by the specific weight of the respective noble metal or the specific weight of the billet is determined with a hydrostatic balance and the dimensions are counter-checked.
RFA surface measurement / determination of fine content
By means of RFA X-ray fluorescence analysis, the noble metal fine content of the ingot surface can be determined without destruction.
The device emits X-rays to the material to be examined, which are reflected by each element in a different wavelength. A sensor receives these back-echo echoes and forwards them to a computer for evaluation, where the material composition is calculated. So you can see in seconds whether it is pure gold, silver, platinum or palladium. However, since the measurement only provides information about the bar surface, further investigations are necessary to determine the homogeneity of the total material.
Measurement of electrical conductivity
The homogeneity and fineness determination of small noble metal bars can be carried out with a conductivity measuring device up to approx. 50 g. For this purpose, a probe is placed on the bar to be examined, which checks the electrical conductivity of the material to be examined. Bars, which are welded in thin films, can be examined through the film. It is then possible to check in tables whether the measured values correspond to the set point values of the bar refinements.
Ultrasonic measurement of ingot homogeneity
In the case of precious metal bars of 100 g or more, the homogeneity of a billet is measured by ultrasonic measurement. In this case, it can be determined whether the system to be investigated consists of fine gold, fine silver, fine platinum or fine palladium, or whether it has been manipulated. With the help of ultrasonic measuring instruments and the knowledge of the sound velocity typical for the particular precious metal, fake or only surface-coated tungsten bars can be exposed as well as formerly genuine armatures filled with foreign materials.