Testing silver with a Sigma Metalytics verifier.

How it works

The verifier's sensor creates a small electromagnetic field and measures how the metal affects it, which gives the metal's electrical resistivity. Silver conducts electricity better than any other metal, so it has the lowest resistivity:

The PRO and Investor models can also read through the whole thickness of a coin or bar, which catches plated pieces and many inserts that a surface test would miss.

What it needs

The piece must fully cover the sensor. Sigma's manual gives minimum sizes for silver, such as 24 mm across and 0.9 mm thick for the built-in sensor, or 8 mm across for the small wand. High-relief designs can give false readings, and the coin and the device should be at about the same temperature.

Its limits, in the maker's words

• Not for jewelry: "None of our devices are designed for testing jewelry of any kind."
• Copper reads close to silver: in Sigma's 2026 reference guide, the passing ranges for .999 silver and for copper overlap. Weight and dimensions have to be checked too.
• Not the only test: Sigma says the verifier "should not be the sole means for identification of counterfeit coins and bars."

Sources

• Sigma Metalytics, Precious Metal Verifier manuals and 2026 resistivity reference guide.
• NIST, Electrical resistivity of copper, gold, palladium and silver (Matula, 1979).
• U.S. Geological Survey, Silver statistics and information.

Silver tests: How to test silver · Specific gravity · XRF · Sigma verifier · Magnet · Acid · Ice · Ping · Is my silver real? · Silver stamps

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