Coin Pinger
Acoustic bullion authentication — free, private, on-device
Coin comparison
French 20 Francs vs Swiss 20 Francs Vreneli
Identical ring: how these two gold coins differ on the scale, under the calipers, and — computed from first-principles physics — in the ring.
Official specifications, side by side
| French 20 Francs | Swiss 20 Francs Vreneli | |
|---|---|---|
| Weight | 6.45161 g | 6.4516 g |
| Diameter | 21 mm | 21 mm |
| Composition | .900 gold (90%) | .900 gold (90%) |
| Mint | Monnaie de Paris | Swissmint |
Expected ring, mode by mode
| Mode | French 20 Francs | Swiss 20 Francs Vreneli |
|---|---|---|
| c0d2 | 4.62–5.82 kHz | 4.62–5.82 kHz |
| c0d3 | 10.73–13.40 kHz | 10.73–13.40 kHz |
The French 20 Francs and Swiss 20 Francs Vreneli share the same mass, diameter, and metal, so the physics gives them the same resonance reference — the ping test cannot tell a genuine one from the other, and doesn't need to. It tells either apart from a wrong-metal fake. Frequencies are computed from each coin's published mass, diameter, and metal via free circular-plate physics — see the methodology.
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