Coin Pinger
Acoustic bullion authentication — free, private, on-device
Authenticity guide
Is my Gold American Eagle 1 oz real?
Four checks — weight, size, magnet, and the ring — catch the overwhelming majority of fakes, because a counterfeit can fake the look but not the physics. Every threshold below is computed from the official spec and our acoustic model.
The 60-second checklist
| Check | Genuine Gold American Eagle 1 oz | Red flag |
|---|---|---|
| ⚖ Weight | 33.931 g ±0.3 g | More than ±0.3 g off |
| 📏 Diameter | 32.7 mm ±0.1 mm | Visibly off, or fails calipers |
| 📏 Thickness | ≈2.87 mm at the rim | Noticeably thick (hiding low density) |
| 🧲 Magnet | No attraction at all | Any pull = steel core |
| 🔔 Ring (c0d2) | 4.34–5.00 kHz | Any peak outside the bands below |
What fakes sound like — computed, metal by metal
A struck disc's ring is fixed by √(stiffness ÷ density). A genuine Gold American Eagle 1 oz rings its fundamental at 4.34–5.00 kHz (higher modes: 10.02–11.42 / 17.38–19.79 kHz). Here is where the same-size coin lands in the metals counterfeiters actually use — computed from published elastic constants, no guesswork:
| Struck in… | Fundamental | Weight at right size | What you'd hear |
|---|---|---|---|
| Genuine gold | 4.34–5.00 kHz | 33.931 g | clear, sustained ring |
| tungsten core | ≈10150 Hz | ≈36.9 g | denser than the 22k alloy — a solid replica runs heavy, so real fakes bury a sized tungsten core; the far-higher ring catches either |
| gilded silver | ≈5900 Hz | ≈20.1 g | rings higher and weighs roughly half of genuine |
| gold-plated copper/brass | ≈7950 Hz | ≈17.2 g | much higher ring and badly underweight |
| gilded lead | ≈2600 Hz | ≈21.7 g | a low dead thud, well underweight |
Plated and base-metal fakes also decay faster — solid precious metal has very low internal damping, so a genuine coin ring lasts; fakes die out. Coin Pinger measures both. Full resonance reference →
Known Gold American Eagle 1 oz fakes — what's actually out there
Two documented tiers: gold-plated brass or copper that fails the scale instantly, and the tungsten-core fake — tungsten matches gold's density within 0.3%, so it passes weight, dimensions, and even surface acid tests (NGC's write-up). The ring is where tungsten loses: far stiffer than gold, it rings dramatically higher — the table above computes exactly where. Counterfeit Gold Eagles inside fake graded slabs are separately documented, so verify certification numbers against the grader's database.
Gold American Eagle 1 oz authenticity — frequently asked
How can I tell if my Gold American Eagle 1 oz is fake?
Run four checks: weight (genuine: 33.931 g ±0.3 g), diameter (32.7 mm ±0.1 mm), the magnet test (genuine gold is not magnetic), and the ring test — a genuine Gold American Eagle 1 oz's fundamental rings at 4.34–5.00 kHz, and every common fake metal rings measurably elsewhere. Passing all four is strong evidence of authenticity; failing any one is a red flag.
Does a fake Gold American Eagle 1 oz stick to a magnet?
Only steel-core fakes do — genuine gold is not magnetic, so any magnetic pull means fake. But most fakes (copper-nickel, plated copper, tungsten) are also non-magnetic, so passing the magnet test proves little on its own. Combine it with weight and the ring.
How much does a fake Gold American Eagle 1 oz weigh?
Depends on the metal: a tungsten-core fake can weigh almost exactly right (33.931 g) because tungsten's density matches gold — that's why tungsten fakes fool scales. Gilded-silver or plated-copper fakes of the right size weigh only 20.1–17.2 g vs the genuine 33.931 g. The ring test catches the tungsten case the scale misses.
Can a counterfeit Gold American Eagle 1 oz pass the ping test?
A wrong-metal fake cannot — the ring is set by √(stiffness ÷ density), and no common fake metal matches gold's. The hardest case is a genuine-alloy counterfeit struck to correct specs; those are rare and expensive to make, and against them the ping test is one strong signal among several — combine it with weight, dimensions, and a trusted seller.