The Gold Britannia is one of the most popular bullion coins, which is why fakes turn up too. Below are the genuine coin's official specifications, the mint's security features and the tests you can do at home.
Genuine coin specifications
| Total weight | not published by the mint |
|---|---|
| Fine metal content | 1 oz t |
| Fineness | 999.9 |
| Alloy | pure gold, no alloy |
| Diameter | 32.69 mm |
| Thickness | not published by the mint |
| Face value | £100 |
| Mint | The Royal Mint |
Security features of the genuine coin
- Latent image: as you tilt the coin, Britannia's trident changes into a padlock. since 2021
- Surface animation: laser micro-detail creates a moving wave effect in the background as the coin is rotated. since 2021
- Laser-made micro-text "DECUS ET TUTAMEN" around the design. since 2021
- Heraldic tincture lines on the Union flag on the shield, which are hard to copy. since 2021
How to check the coin at home
- Measure the diameter (32.69 mm) with calipers. A copper, brass or lead fake with the right weight has the wrong dimensions, because those metals have a different density. Tungsten is almost as dense as gold, so a well-made fake with a tungsten core can pass this test.
- Hold a strong neodymium magnet to it. Gold is not magnetic. Note: this test will not catch fakes made of tungsten or copper.
- Ping test (works best for silver): gently tap the coin against another coin. Genuine silver rings clearly for a second or two; a fake with a base-metal core sounds short and dull. It works best side by side with a coin you know is genuine.
- Look at the coin under a loupe and compare it with a genuine one: sharpness of the design, lettering, edge and the security features listed above.
- The most reliable non-destructive test is an electromagnetic or ultrasonic verifier (e.g. Sigma Metalytics). Many dealers have one, so ask them to test the coin when you sell.
No home test is 100% certain. The simplest protection is buying from a known dealer and, if in doubt, having the coin verified by a specialist.