How to test the authenticity of gold and silver
There are currently several methods of testing gold and other precious metals, each of which has its advantages and disadvantages. In general, it is always recommended to combine several methods.
The first and simplest test is usually the magnet test. The test object is positioned at a 45° angle and a magnet is placed on top of it. No precious metal is magnetic, and the magnet must not be retained attached to the sample. Rare metals are diamagnetic, which means that the magnet should slowly slide down the tested metal, but there is no strong magnetic field between them. This method is simple and inexpensive, but only reveals very cheap and low-quality counterfeits.
Acid Test on Stone
The acid test is the most common and the oldest way of testing, which we can see mainly in jewelry and pawn stores. The tested sample is scratched several times on testing stone until the thin line is created. This is followed by the application of nitric acid at various concentrations. If the line does not disappear or change the color after contact with the acid, it is the appropriate metal purity according to the concentration used. The major drawback of this test is that it leaves traces and scratches on the test item. This method can not detected heavy plating or a fake core without serious damage to the tested item.
Electrical properties test
An analysis of electrical conductivity and metal resistance makes it possible to quickly detect changes in material properties below the surface. It can detect a heavy plating or tungsten rods hidden in the core. It is almost impossible to duplicate electrical resistance, weight and metal size. This method offers affordable, fast and non-destructive metal testing with high reliability. PMV verifiers can test the sample even through plastic packages, certification cards, or numismatic cases.
X-ray fluorescence (XRF) and spectrography
Modern XRF devices and spectrometers can determine the exact composition and concentration of individual elements in the tested sample. The advantage of this method is that there is no damage to the material, the test is quick and simple. The analysis is carried out a few micrometres in depth, which can not reveal fake tungsten core or heavy coating. Both methods make it possible to test metal without damage, the disadvantage is the high cost of the equipment.
Industrial ultrasounds allow you to see inside the material. This method is used to detect fake cores and defects under the surface mainly for large bars and bullions. In small objects, the use of ultrasound is problematic. Ultrasonic testing is mainly used by refineries and banks. High cost of ultrasonic devices makes it inaccessible for a common investors.