See demonstration video on Youtube

 

Spectryx CoinPen+ is an inductive conductivity measurement tool designed for precious metal coins. It uses Eddy current damping between the coin and a measurement coil to infer the conductivity of the coin. The penetration depth of the field is about 0.2mm, so it can verify conductivity of coins with thin gold coatings. This allows detection of counterfeit coins and bullions (in thin plastic packages) based on conductivity value. The conductivity (sigma) value can be used to complement other measurements such as dimensions, weight and density to verify authenticity of coins.