What types of counterfeits are there?
1. “Highway Gold”: These are counterfeits that are sold as real gold but are actually made of a different material and are merely gold-plated. For counterfeits of this type made with tungsten, conductivity measurement using the GoldScreenSensor/GoldScreenPen is highly effective for identifying the counterfeit. If the object is made of a different material (e.g., brass), then its weight, dimensions, and density will also differ from the original.
2. Under- or Over-Alloying: This type of counterfeit occurs primarily in jewellery. In this case, a gold content different from what is actually present is stamped on the object. For example, a gold necklace might bear a 750 hallmark, even though it is actually made only of 333 gold. This type of counterfeit is best identified using the CaratScreenPen.
3. Cores Made of Foreign Metal: These objects often consist of a relatively thick layer of gold but have a core made of a different metal (usually tungsten). Their dimensions, weight, and density are very well imitated, which is why these counterfeits are very difficult to identify. For thicker bars, the BarScreenSensor is suitable; for smaller ones, the GoldScreenSensor or the GoldScreenPen can also be used.
4. Counterfeit hallmarks and stamps: This type of counterfeit is most common in the jewelry and coin sectors, but has also appeared in gold bars in recent years. Older coins with high collector’s value are imitated, and attempts are made to sell these specifically. These counterfeits can be detected by carefully examining the minting or by testing the physical properties using various devices and methods. In the case of gold bars—usually weighing 1 kg—illegally mined gold is often stamped with the mark of renowned mints, such as Argor-Heraeus, and sold as genuine. With this type of bar, one should pay particular attention to the security features that have since been incorporated, similar to those found on banknotes. Otherwise, the fineness differs only minimally from the 999.99 of the originals, as these counterfeits have not been manufactured to the same high standard.