How to Detect Fake Coin Forgeries

Author: Connor Campbell - Bullion & Economics Editor

Published: 12 Oct 2022

Last Updated: 31 Jan 2023


We have been in business for over 58 years, so we have plenty of expertise when it comes to identifying suspect coins of any kind. Numerous counterfeits exist; most are obvious and easy to spot, but there are some which are high quality, and more difficult to spot.

What Is a Fake Coin?

A fake coin also known as counterfeit or suspects are coins that are designed for general circulation at face value, for thousands of years for criminal gain. One of the most well-known counterfeiters is Frank Bourassa who counterfeited over $250 million American $20 bills!

For a comprehensive list of fake sovereigns, please see our Fakes, Forgeries and Counterfeits – Sovereigns Article.

2021 Proof Sovereign Measured With Vernier Gauge

2021 Proof Sovereign Measured With Vernier Gauge

This is a 2021 gold sovereign, a proof which as we all know are minted to the highest standards. We calibrated or zeroed the calipers before use. As you can see, the reading was 21.93mm, a discrepancy of .12mm, or 0.544%. As the area is proportional to diameter squared, this would increase the error, to 1.085%. Add in, or rather multiply by any error in the thickness measurement, and any results are likely to be suspect at least.

2021 Proof Sovereign Measured With Leveridge Gauge

In case anybody thinks using a £10 vernier gauge does not lend itself to precision, we did the same thing with a Leveridge gauge, a specialised type of micrometer: with similar results. Leveridge Gauges are mainly used by jewellers, diamond merchants, and gemmologists.

Now for the thickness or height measurements:

2021 Proof Sovereign Measured With Leveridge Gauge
Exploring The Height and Rim Using a Leveridge Gauge

Measuring The Height and Rim Using a Leveridge Gauge

There is a third height measurement, namely the highest parts of the design on both sides. The height on each side is known as the relief.

Expert Coin Dealers

All the coins we buy and sell are authenticated as genuine. We have over 58 years’ experience dealing with all kinds of gold bullion coins, so we feel we are well-placed to refer to ourselves as expert numismatists.  

We are not afraid to call out such malpractice undertaken by direct competitors, because such actions are incredibly unfair and serve to undermine trust in our industry. We would expect such unscrupulous behaviour from some backstreet pawn shop brokers and the numerous fraudsters on eBay, but from a supposedly legititmate dealer, this episode is all the more disappointing.

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