Coin Pinger
Acoustic bullion authentication — free, private, on-device
Gold coin guides
Gold coin ping testing
Gold rings lower and shorter than silver of the same size — it is denser and slightly less stiff, and √(stiffness ÷ density) sets the pitch. That contrast is exactly what makes the ping test powerful for gold: tungsten, the only affordable metal with gold's density, is far stiffer and rings dramatically higher, so a wrong-metal core can't hide from the ring even when it fools a scale. 22k alloy coins (Krugerrand, Eagle, Sovereign) ring a touch higher than .9999 fine coins of the same size.
31 full-size gold coins — official specs & expected fundamental
| Coin | Weight | Diameter | Fineness | c0d2 ring | |
|---|---|---|---|---|---|
| Austrian 1 Ducat | 3.49 g | 19.75 mm | .986 gold | 2.76–3.32 kHz | |
| Austrian 100 Corona | 33.875 g | 37 mm | .900 gold | 2.52–3.17 kHz | |
| Austrian 8 Florins / 20 Francs | 6.4516 g | 21 mm | .900 gold | 4.62–5.82 kHz | |
| British Half Sovereign | 3.994 g | 19.3 mm | .9167 gold | 4.01–5.05 kHz | |
| French 20 Francs | 6.45161 g | 21 mm | .900 gold | 4.62–5.82 kHz | |
| German 20 Mark | 7.965 g | 22.5 mm | .900 gold | 4.33–5.45 kHz | |
| Gold American Eagle 1 oz | 33.931 g | 32.7 mm | .9167 gold | 4.34–5.00 kHz | |
| Gold Azadi | 8.13 g | 22 mm | .900 gold | 5.07–5.85 kHz | |
| Gold Britannia 1 oz | 31.104 g | 32.69 mm | .9999 | 3.28–3.94 kHz | |
| Gold Britannia 1 oz (1987–2012) | 34.05 g | 32.69 mm | .9167 gold | 4.36–5.02 kHz | |
| Gold Britannia 1 oz (2013–2025) | 31.104 g | 32.69 mm | .9999 | 3.28–3.94 kHz | |
| Gold Buffalo 1 oz | 31.108 g | 32.7 mm | .9999 | 3.28–3.93 kHz | |
| Gold Double Eagle $20 | 33.436 g | 34 mm | .900 gold | 3.48–4.39 kHz | |
| Gold Kangaroo 1 oz | 31.103 g | 32.6 mm | .9999 | 3.26–4.04 kHz | |
| Gold Krugerrand 1 oz | 33.93 g | 32.77 mm | .9167 gold | 4.30–4.96 kHz | |
| Gold Libertad 1 oz | 31.1 g | 34.5 mm | .999 | 2.65–3.17 kHz | |
| Gold Lunar Series III 1 oz | 31.107 g | 32.6 mm | .9999 | 3.26–4.04 kHz | |
| Gold Maple Leaf 1 oz | 31.103 g | 30 mm | .9999 | 4.62–5.55 kHz | |
| Gold Panda 1 oz (pre-2016) | 31.103 g | 32.05 mm | .999 | 3.55–4.26 kHz | |
| Gold Panda 15 g | 15 g | 27 mm | .999 | 3.40–4.08 kHz | |
| Gold Panda 3 g | 3 g | 18 mm | .999 | 3.44–4.13 kHz | |
| Gold Panda 30 g | 30 g | 32 mm | .9999 | 3.45–4.13 kHz | |
| Gold Panda 8 g | 8 g | 22 mm | .999 | 4.11–4.94 kHz | |
| Gold Philharmonic 1 oz | 31.103 g | 37 mm | .9999 | 2.00–2.40 kHz | |
| Gold Sovereign | 7.988 g | 22.05 mm | .9167 gold | 4.93–5.70 kHz | |
| Mexican 10 Pesos | 8.3333 g | 22.5 mm | .900 gold | 4.53–5.70 kHz | |
| Mexican 2.5 Pesos | 2.0833 g | 15.5 mm | .900 gold | 5.03–6.33 kHz | |
| Mexican 20 Pesos | 16.6666 g | 27.5 mm | .900 gold | 4.06–5.11 kHz | |
| Mexican 5 Pesos | 4.1666 g | 19 mm | .900 gold | 4.45–5.61 kHz | |
| Mexican 50 Pesos Centenario | 41.6666 g | 37 mm | .900 gold | 3.09–3.90 kHz | |
| Swiss 20 Francs Vreneli | 6.4516 g | 21 mm | .900 gold | 4.62–5.82 kHz |
22 fractional sizes (1/2 · 1/4 · 1/10 oz)
| Coin | Weight | Diameter | Fineness | c0d2 ring | |
|---|---|---|---|---|---|
| Gold American Eagle 1/10 oz | 3.393 g | 16.5 mm | .9167 gold | 6.68–7.72 kHz | |
| Gold American Eagle 1/2 oz | 16.966 g | 27 mm | .9167 gold | 4.66–5.38 kHz | |
| Gold American Eagle 1/4 oz | 8.483 g | 22 mm | .9167 gold | 5.28–6.11 kHz | |
| Gold APMEX Round 1/4 oz | 7.776 g | 21.7 mm | .9999 | 4.22–5.07 kHz | |
| Gold Britannia 1/10 oz | 3.13 g | 16.5 mm | .9999 | 5.09–6.10 kHz | |
| Gold Britannia 1/2 oz | 15.6 g | 27 mm | .9999 | 3.54–4.24 kHz | |
| Gold Britannia 1/4 oz | 7.78 g | 22 mm | .9999 | 4.00–4.80 kHz | |
| Gold Kangaroo 1/10 oz | 3.111 g | 16.6 mm | .9999 | 4.85–6.00 kHz | |
| Gold Kangaroo 1/2 oz | 15.552 g | 25.6 mm | .9999 | 4.29–5.30 kHz | |
| Gold Kangaroo 1/4 oz | 7.777 g | 20.6 mm | .9999 | 5.11–6.33 kHz | |
| Gold Krugerrand 1/10 oz | 3.393 g | 16.55 mm | .9167 gold | 6.60–7.63 kHz | |
| Gold Krugerrand 1/2 oz | 16.965 g | 27.07 mm | .9167 gold | 4.62–5.32 kHz | |
| Gold Krugerrand 1/4 oz | 8.482 g | 22.06 mm | .9167 gold | 5.23–6.04 kHz | |
| Gold Libertad 1/10 oz | 3.11 g | 16 mm | .999 | 5.71–6.86 kHz | |
| Gold Libertad 1/2 oz | 15.552 g | 29 mm | .999 | 2.65–3.18 kHz | |
| Gold Libertad 1/4 oz | 7.78 g | 23 mm | .999 | 3.35–4.02 kHz | |
| Gold Maple Leaf 1/10 oz | 3.11 g | 16 mm | .9999 | 5.71–6.86 kHz | |
| Gold Maple Leaf 1/2 oz | 15.552 g | 25 mm | .9999 | 4.79–5.76 kHz | |
| Gold Maple Leaf 1/4 oz | 7.776 g | 20 mm | .9999 | 5.85–7.03 kHz | |
| Gold Philharmonic 1/10 oz | 3.121 g | 16 mm | .9999 | 5.74–6.88 kHz | |
| Gold Philharmonic 1/2 oz | 15.552 g | 28 mm | .9999 | 3.05–3.65 kHz | |
| Gold Philharmonic 1/4 oz | 7.78 g | 22 mm | .9999 | 4.00–4.80 kHz |
Fractional coins are smaller, so they ring higher and carry fewer readable modes — coins under 25 mm sit at the edge of reliable phone-mic testing; lean harder on the weight and diameter checks. See the fractional-size index.
Every frequency is computed from first-principles free-plate physics using the mint's published mass and diameter — see the methodology. Each coin's page lists all vibration modes, tolerances, and a physics explainer.
Coin not listed?
Compute the expected ring for any coin from its mass, diameter, and metal with the resonance calculator — or calibrate your own genuine coin directly in the app.