Coin Pinger
Acoustic bullion authentication — free, private, on-device
Gold coin guide
Gold Kangaroo 1/2 oz — ping test & specs
The half-ounce Gold Kangaroo is a .9999 gold Perth Mint coin at 25.6 mm. Its smaller size raises its ring frequencies relative to the 1 oz coin.
Opens the free tester with this coin preselected — audio never leaves your device.
Official specifications
| Weight | 15.552 g |
| Diameter | 25.6 mm |
| Composition | .9999 fine gold |
Source: Perth Mint. Coin Pinger checks measured weight and diameter against these values.
Expected resonance range
Provisional confidence*| Mode | Expected ring | Recommended variance |
|---|---|---|
| c0d2 | 4.29–5.30 kHz | ±10.6% |
| c0d3 | 9.92–12.18 kHz | ±10.2% |
| c0d4 | 17.28–21.20 kHz | ±10.2% |
A genuine Gold Kangaroo 1/2 oz 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 the issue is struck at slightly varying thickness across years. The higher modes also carry a small thick-plate centre correction, since a real coin is not infinitely thin. The provisional-confidence tag reflects how well-established this metal's constants are: Computed from .9999 gold's annealed modulus — the least-certain material input, so the band is widened and this reference is best confirmed by calibrating a coin you know is genuine. 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 Kangaroo 1/2 oz 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 Kangaroo 1/2 oz
- 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.