How to Spot Fake Gold — The Complete Guide

Gold bullion counterfeiting is a multi-billion-pound criminal industry. As gold prices have risen over the past two decades, the financial incentive to produce convincing fakes has grown proportionally. Modern counterfeiters use industrial-grade equipment and materials that can fool even experienced dealers.

The most dangerous fakes use tungsten cores plated with genuine gold. Because tungsten’s density (19.25 g/cm³) is nearly identical to gold’s (19.30 g/cm³), these fakes pass the most commonly used tests: weight checks, water displacement, and even X-ray fluorescence surface analysis.

Whether you’re buying from a dealer, at a coin show, or through a peer-to-peer marketplace, knowing how to verify authenticity protects your investment and gives you confidence in every transaction.

Start every authentication by examining the coin carefully under good lighting. Look for sharp, well-defined details in the design — the Queen’s hair strands on a Britannia, the eagle feathers on an American Gold Eagle, or the edge lettering on a Krugerrand. Genuine coins are struck with enormous pressure using hardened steel dies, producing crisp, consistent detail.

Check the colour under natural light. Pure 24-carat gold (used in Maple Leafs, Philharmonics, and Kangaroos) has a distinctive warm yellow. Alloyed 22-carat gold (Krugerrands, Sovereigns, Eagles) has a slightly redder tone due to copper content. A coin that looks too pale, too orange, or has an uneven colour may be suspect.

Examine the edge. Many coins have reeded (ridged) edges or specific lettering. Count the reeds if possible — they should be uniform and evenly spaced. Poorly made counterfeits often show irregular edges, seam lines, or slightly rounded reeds.

Every gold coin has precisely specified mass, diameter, and thickness values published by the issuing mint. A genuine 1 oz Krugerrand weighs exactly 33.93 grams, measures 32.77 mm in diameter, and is 2.84 mm thick. Deviations beyond manufacturing tolerances of ±0.05 g (weight) and ±0.15 mm (diameter) warrant further investigation.

You need a precision scale with at least 0.01 g resolution, though 0.001 g is preferable. Digital callipers with 0.01 mm resolution handle diameter and thickness. You can also use the free Dimension Camera tool on the EON Bullion website for phone-based measurement against a known reference length.

Weight and dimension testing catches crude counterfeits made from the wrong metal or with incorrect sizing. However, it cannot detect tungsten-core fakes, which are manufactured to exact specifications. This is why dimensional checks should always be combined with conductivity testing.

Gold is diamagnetic — it is very weakly repelled by a magnetic field. A strong neodymium magnet should slide slowly down a tilted gold coin or bar, neither sticking nor falling freely. This sliding effect is caused by eddy currents induced in the gold, which create a gentle braking force.

The magnet slide test can detect ferromagnetic counterfeits (those containing iron, nickel, or steel) because these metals cause the magnet to stick. However, tungsten is non-magnetic, so a tungsten-core fake passes the magnet test just as easily as genuine gold.

While the magnet slide test is simple and inexpensive, it provides limited information. It should be considered a preliminary screening tool rather than a definitive authentication method.

When struck on its edge, a genuine gold coin rings with a clear, sustained tone. The frequency of this ring is determined by the coin’s composition, dimensions, and internal structure. Each coin type has a characteristic frequency that can be measured using a microphone and frequency analysis software.

A 1 oz Gold Maple Leaf rings at approximately 4,891 Hz, while a Vienna Philharmonic rings at approximately 2,115 Hz. A tungsten-core fake will produce a noticeably different sound because tungsten’s speed of sound (5,220 m/s) differs from gold’s (3,240 m/s).

Acoustic testing is non-destructive and can be performed with a smartphone. The EON Ping Tester uses the Web Audio API to capture and analyse the frequency spectrum in real time, comparing against known reference values.

Eddy current testing is the most reliable non-destructive method for authenticating gold bullion. It works by measuring the electrical conductivity of the entire sample volume, not just its surface. Pure gold has a conductivity of 44.0 MS/m, while tungsten is only 17.9 MS/m — a difference of more than 2:1 that is impossible to fake.

EON’s eddy current method uses a neodymium pendulum that swings past the coin. The eddy currents induced in the coin create a braking force that brings the pendulum to rest at a specific angle. This angle is unique to the coin’s conductivity and volume, producing a signature that can be compared against published reference values. The free online simulator and optional Flat-Pack Pendulum Kit both use this principle.

A reading within ±5% of the predicted value confirms authenticity. Tungsten-core fakes consistently fall outside this tolerance because their bulk conductivity differs dramatically from genuine gold. No amount of surface plating can mask the conductivity of the core material.

No single test should be relied upon in isolation. The most robust authentication combines multiple independent methods, each catching a different category of counterfeit. The EON multi-factor protocol uses four tests: dimensional verification, weight check, acoustic ping, and eddy current analysis.

Each test that passes increases confidence in authenticity. The EON Multi-Factor Authentication Score aggregates results from all completed tests into a single 0–100 confidence rating, giving buyers and sellers a clear, quantified measure of authentication certainty.

For peer-to-peer trading, where buyer and seller may be in different countries, this multi-factor approach provides the trust infrastructure that makes transactions possible. Authentication is not just about detecting fakes — it’s about building a marketplace where every participant can trade with confidence.