Coin Pinger
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Gold coin guide
Gold Double Eagle $20 — ping test & specs
The Saint-Gaudens $20 Double Eagle (1907–1933) is a classic 90% gold US coin holding just under one ounce of gold. Its copper alloy and larger 34 mm size shape its ring.
Opens the free tester with this coin preselected — audio never leaves your device.
Official specifications
| Weight | 33.436 g |
| Diameter | 34 mm |
| Thickness | 2.41 mm |
| Composition | .900 gold (90%) |
Source: United States Mint. Coin Pinger checks measured weight and diameter against these values.
Expected resonance range
Good confidence*| Mode | Expected ring | Recommended variance |
|---|---|---|
| c0d2 | 3.48–4.39 kHz | ±11.5% |
| c0d3 | 8.06–10.08 kHz | ±11.1% |
| c0d4 | 14.04–17.54 kHz | ±11.1% |
A genuine Gold Double Eagle $20 rings within these ranges at its c0d2/c0d3/c0d4 vibration modes, fixed by its size and metal. The recommended variance is how far a genuine specimen's ring can sit from each center — built up in quadrature from real manufacturing tolerance and temperature (under 1%), phone-mic capture reproducibility (≈4%), an extra allowance on the fundamental for minting-asymmetry splitting, and a per-metal model-uncertainty term (largest for .9999 gold, whose modulus is least certain). This coin's band is widened further because circulated 90%-silver classics lose mass and edge crispness with wear, spreading their ring. The higher modes also carry a small thick-plate centre correction, since a real coin is not infinitely thin. The good-confidence tag reflects how well-established this metal's constants are: Computed from 22k-gold alloy constants, which are slightly less certain than silver; the band is set accordingly. These are guidance bands, not exact values — see the methodology for the exact formula, or calibrate your own coin in the app for a specimen-exact reference and tighten each peak per coin.
* These are computed guidance ranges. Certain your Gold Double Eagle $20 is genuine but it won't match? Send us its ring — we'll dig in and improve the reference.
🎙 Submit sample pingsHow to ping test a Gold Double Eagle $20
- Hold — grip the coin by its center (a nodal point) in a coin ping-test holder so the rim rings freely; a fingertip at the center is a last resort.
- Tap — strike the edge with a striker near the microphone.
- Read the verdict — MATCH or NO MATCH against the peaks above, plus weight and size checks.
Gold Double Eagle $20 — frequently asked
How much does a Gold Double Eagle $20 weigh?
The official specification is 33.436 g in .900 gold (90%) (source: United States Mint). Coin Pinger's weight check allows ±0.3 g by default. Circulated specimens lose a little mass to wear, so weigh toward the low side of that window.
What size is a Gold Double Eagle $20?
34 mm in diameter and 2.41 mm thick at the rim, per United States Mint. Note the average disc thickness is less than the rim caliper reading — the raised rim and relief concentrate metal at the edge.
What frequency does a genuine Gold Double Eagle $20 ring at?
Its fundamental (c0d2) vibration mode is computed to ring in the 3.48–4.39 kHz range, with higher modes near 8.06–10.08 kHz and 14.04–17.54 kHz. These are first-principles physics computations from the coin's published mass, diameter, and metal — not measurements of sample coins.
Why does my genuine Gold Double Eagle $20 ring slightly off the listed frequencies?
Wear is the biggest factor for the Gold Double Eagle $20: circulated 90%-silver classics lose mass and edge crispness, which spreads the ring across specimens. On top of that, phone-mic capture moves a genuine peak a few percent tap-to-tap (strike point, how you hold it, the mic itself). That's why this reference band is wider than a modern bullion coin's.
Does ping testing damage a Gold Double Eagle $20?
No — the test needs only a light tap on the edge with a non-marring striker (a wooden pencil or plastic stylus works well), far gentler than normal handling. Hold the coin at its center so the rim can ring freely.