How to Test Gold & Silver Bullion Coins using CoinVerify

A simple step-by-step guide to using your CoinVerify testing tool to check a coin's diameter, thickness, weight and magnetic response.

1. Place your coin into the matching diameter recess.

2. Hold the integrated magnet (or the magnetic keyring) close to the coin - A deep filled counterfeit will be attracted to the integrated strong magnet.

3. Insert the coin into the thickness slot to check its width - A genuine coin should pass all the way through to the other side.

4. Weigh the coin using accurate digital jewellery or mini scales (not included) and compare the weight with the values shown on the tester.

5. If the diameter, thickness, and weight all match the specifications outlined on the tester tool, the coin is likely to be genuine.

6. If the coin fails any part of the test, further advanced testing may be necessary.

The Science Behind the Test:

Precious metals have characteristic densities, creating a direct relationship between a coin’s metal composition, physical dimensions and weight.

Why check more than one characteristic?
Diameter, thickness and weight work together. A counterfeit may match the diameter of a genuine coin, but if it is made from a lower-density material, maintaining that diameter and thickness will generally result in the wrong weight. Matching the weight instead requires additional volume, which can reveal itself through incorrect dimensions.

A genuine bullion coin is manufactured to carefully controlled specifications for diameter, thickness, weight and metal composition. If a counterfeiter substitutes the correct precious-metal alloy with a material of a different density, matching the coin’s appearance alone is not enough. To achieve the correct weight, its volume — and therefore one or more of its physical dimensions — must change.

CoinVerify takes advantage of this fundamental relationship by checking diameter, thickness and weight together. A counterfeit made from an incorrect material may be able to replicate one or even two of these characteristics, but reproducing all of them becomes considerably more difficult when the substitute material has a different density.

The additional magnet test provides another useful screening layer by helping identify strongly magnetic metals that would be inconsistent with many gold and silver bullion coins.

It’s simple physics: the metal, volume and mass are intrinsically linked.

Understanding the Different Types of Fake Sovereigns - A Case Study:

Not all counterfeit sovereigns are the same. Some are relatively easy to identify, while others can be convincing enough to deceive experienced collectors.

Jeweller’s copies are commonly encountered older reproductions, often made from real gold but sometimes at a different purity from genuine Royal Mint sovereigns. Although they may look authentic, differences in metal composition can result in variations in weight, diameter or thickness — and our testers have identified examples of these coins on numerous occasions.

Contemporary counterfeits were produced during the same period as genuine sovereigns with the intention of passing them as genuine currency. They may contain lower-purity gold, base metals or alternative alloys and can often be identified through differences in their physical specifications or design.

Modern counterfeits can be highly convincing, using modern manufacturing techniques and, in some cases, gold-plated base metals. While appearance alone may not reveal the deception, incorrect materials often result in discrepancies in diameter, thickness, weight or magnetic response.

This is why checking several physical characteristics together is so valuable. A coin that falls outside its expected specifications should be treated with caution and referred for further professional examination where necessary.

A Real-World Example: The Sovereign That Started CoinVerify

Some counterfeit sovereigns are remarkably convincing. We experienced this first-hand with a 1925 Great Britain Sovereign that appeared genuine enough for us to send it to a specialist for submission to NGC grading.

It wasn't until the coin was examined during the grading process that it was identified as not genuine. Subsequent XRF analysis indicated that the coin was a 21-carat gold jeweller's copy rather than a genuine 22-carat Sovereign.

What made the experience particularly interesting was just how convincing the coin appeared. Visually, there was very little to raise suspicion. However, when checked using our physical Sovereign tester, its dimensions were fractions of a millimetre outside the expected specifications.

Had we performed these simple dimensional checks beforehand, we could have identified the discrepancy before sending the coin away — saving both time and money. This was the inspiration behind the development of our first testing tool, The Gold Sovereign Tester.

Why We Believe Physical Screening Matters

This wasn't an isolated experience. A number of CoinVerify customers have subsequently contacted us after discovering unsuspected counterfeit or incorrect-specification coins in their own collections using our testers.

It demonstrates an important principle behind CoinVerify: a convincing appearance doesn't necessarily mean the physical specifications are correct.

Checking diameter, thickness, weight and magnetic response takes only moments and can provide an invaluable first line of screening before buying, selling, grading or investing further money in a coin.

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