Coin Authenticity Check: Interactive Calculator | Verify Your Bullion Coin
Equipment Recommendations
30–80 EUR · min. 0.01 g resolution, better 0.001 g
15–40 EUR · accuracy ±0.02 mm, for diameter and thickness
5–10 EUR · for the magnet test (diamagnetic testing)
Note: The authenticity check is based on physical measurements and does not replace professional analysis (XRF, ultrasound). For high-value coins, we additionally recommend verification by a precious metals dealer.
Detailed weight check with traffic light system and tolerances.
Check diameter and thickness in isolation.
Melt value for alloys, bars and jewelry.
"Is my coin authentic?" — The Ultimate Guide
With gold prices at record levels, the risk of counterfeit bullion coins has never been higher. The good news: Physics cannot be faked. When weight, diameter and thickness all match simultaneously, a counterfeit is physically almost impossible.
The 5 verification steps in the right order
Check strike quality, details, reeding and color tone.
Precision scale (0.01 g): compare with target weight.
Measure diameter & thickness with caliper.
Place N52 magnet on tilted coin.
Tap: genuine rings long and clear.
Complete set for under 100 EUR
With these three tools you cover the most important physical tests and detect over 95% of all counterfeits.
Metal Densities — Why Physics Exposes Counterfeiters
Every material has a unique density. If a counterfeiter wants to achieve the correct weight but with a different material, the dimensions must change.
Calculation Example: Copper Counterfeit
A 1 oz gold coin (31.103 g) at gold density has a volume of ~1.61 cm³. Copper (8.96 g/cm³) would require ~3.47 cm³ — 2.15× as much. The coin would be ~4.3 mm thick instead of 2.8 mm. Any caliper would detect this.
Tungsten — the greatest threat
Tungsten at 19.25 g/cm³ has nearly identical density to gold (difference only 0.36%). Weight and dimensions can be almost perfect.
Specifications and Tolerances of the Most Important Bullion Coins
The following table shows the official specifications of the ten most-traded 1 oz bullion coins. Weight, diameter and thickness are the three measurements you can check with the calculator above. The weight tolerance indicates the range permitted by the mint — if your coin falls within this range, it is considered flawless.
| Coin | Fineness | Weight | Tolerance | Diameter | Thickness |
|---|---|---|---|---|---|
|
🇨🇦
Maple Leaf
|
999.9‰ | 31.103 g | ±0.030 g | 30.00 mm | 2.87 mm |
|
🇦🇹
Vienna Philharmonic
|
999.9‰ | 31.103 g | ±0.030 g | 37.00 mm | 2.00 mm |
|
🇿🇦
Krugerrand
|
916.7‰ | 33.930 g | ±0.070 g | 32.77 mm | 2.84 mm |
|
🇺🇸
American Eagle
|
916.7‰ | 33.931 g | ±0.060 g | 32.70 mm | 2.87 mm |
|
🇺🇸
American Buffalo
|
999.9‰ | 31.108 g | ±0.030 g | 32.70 mm | 2.95 mm |
|
🇬🇧
Britannia
|
999.9‰ | 31.103 g | ±0.030 g | 32.69 mm | 2.55 mm |
|
🇦🇺
Kangaroo (Nugget)
|
999.9‰ | 31.103 g | ±0.030 g | 32.10 mm | 2.65 mm |
|
🇨🇳
China Panda
|
999.0‰ | 30.000 g | ±0.030 g | 32.00 mm | 2.60 mm |
|
🇬🇧
Sovereign
|
916.7‰ | 7.988 g | ±0.016 g | 22.05 mm | 1.52 mm |
|
🇲🇽
Libertad
|
999.0‰ | 31.103 g | ±0.030 g | 34.50 mm | 2.69 mm |
All data for 1 oz variants (Sovereign: 7.988 g). Weight tolerances according to official mint specifications. You can find the weight check with tolerance traffic light in the Weight Checker.
The Caliper — Measuring Correctly in 3 Steps
A digital caliper (15–40 EUR) is the most important tool after the scale. With ±0.02 mm accuracy you can detect any relevant dimensional deviation.
Close caliper, press ZERO button. Measuring surfaces must be clean & dry.
Place coin between outer jaws, exactly across the center. Rotate 3× (60°), take average.
Between depth measuring faces. Always in the center, not at the edge. Measure 3×, take average.
Common Measurement Errors
The Magnet Test — Quick, Cheap, Effective
Gold, silver and platinum are diamagnetic — they are minimally repelled by magnets. Counterfeit materials like iron or nickel are ferromagnetic and are strongly attracted.
How the test works
Hold coin at an angle (~45°), place a strong neodymium magnet (N52) on the top edge. On genuine precious metal, the magnet slides slowly and evenly — much slower than over glass. Eddy currents in the conductive metal brake the magnet.
Interpreting the results
Limitations: Copper and brass are also non-magnetic — a copper counterfeit passes the magnet test. Tungsten is weakly paramagnetic (minimally attracted). The magnet test is an exclusion method, not proof — always combine with weight and dimensions.
The Ping Test / Sound Test
Every material has a characteristic resonance frequency. Genuine precious metal coins sound clear and long (2–5 seconds), counterfeits sound dull and short.
Balance the coin on your fingertip or a pencil — as little contact as possible.
Lightly tap the edge with another coin or a pencil.
Pay attention to duration, clarity and pitch. App measurement recommended.
Typical coin sound frequencies
Apps like "CoinTest" or "Bullion Test" measure the frequency via smartphone microphone and compare with reference values.
Detecting tungsten via sound test
Despite nearly identical density, tungsten has a completely different elasticity (Young's modulus: 411 GPa vs. gold 79 GPa). This leads to measurably higher resonance frequency and a shorter, sharper sound. The ping test is one of the most reliable methods for tungsten detection.
Counterfeit Risk and Features of the Most Important Bullion Coins
Each mint uses unique security features. The following overview shows key features and the most common counterfeit weak points.
- Fine reeding (160 serifs)
- Sharp springbok details
- Micro-text in mountains (from 2017)
- Blurry hoof details
- Wrong color tone (too yellow)
- Incorrect reeding count
- DNA micro-laser engraving (from 2014)
- Radial background lines
- Tightest weight tolerance
- Missing micro maple leaf
- Smooth background
- Wrong weight (31.1 instead of 31.103)
- 239 reed lines on edge
- Edge notch (from Type 2, 2021)
- Hidden security features
- Wrong color tone
- Missing edge notch
- Liberty details too smooth
- Detailed orchestra instruments
- Organ pipe relief
- Distinctive format 37×2 mm
- Blurry string details
- Wrong edge bar
- Wrong dimensions
- Latent image (castle/Britannia)
- Micro-text ring
- Surface Animation Technology
- Missing latent image
- Static wave pattern
- Missing micro-text
- Annually changing design
- 3D fur texture
- Temple of Heaven detail
- Wrong design for mint year
- Flat fur texture
- Blurry temple details
- Micro-engraving (from 2018)
- Changing kangaroo design
- Fine fur details
- Missing micro-feature
- Blurry fur details
- Wrong mint year design
Counterfeit Risk — What do the levels mean?
Very frequently counterfeited. Exercise particular caution when buying from private sellers or from abroad.
Counterfeits regularly in circulation. At least 2–3 tests recommended.
Counterfeits occasionally known. Standard testing is usually sufficient.
Rarely counterfeited. Complex format or low demand from counterfeiters.
When to See a Professional — XRF, Archimedes and Ultrasound
Home tests (weight, dimensions, magnet, sound) detect most counterfeits. For large investments or suspicion, professional methods are recommended.
Determines the exact elemental composition of the surface (~0.01 mm depth). Detects wrong alloys immediately.
Weigh coin, submerge in water, measure displacement → calculate density. Gold: 19.32 g/cm³, Crown Gold: 17.12 g/cm³.
Measures the speed of sound: Gold 3,240 m/s vs. Tungsten 5,220 m/s — over 60% difference.
Recommendation: For investments above 5,000 EUR, an XRF analysis before purchase is worthwhile. Most reputable precious metals dealers offer this service free of charge or for a small fee.