Guide
Electronic gold testers: what they measure.
A handheld electronic gold tester reads karat from a small spot on the surface, with no acid on the item itself. It's tidier than an acid kit, but it shares the same blind spot: it can't see under plating.
Updated October 28, 2026
How they work
The common type uses a pen-like probe with a tip wetted by a testing solution. Touching the tip to the metal forms a tiny battery-like cell; the tester passes a small current and reads how the metal responds, which differs by karat. Before testing, you calibrate it on known gold and file a small spot on the piece. One popular model reads from 8K to 24K, platinum, or "not gold."
Its limits
- Surface only. It reads the spot it touches. Plating can be a fraction of a micron thick, so the spot has to be filed through it.
- White gold can read slightly lower than its stamp, its maker says.
- Not for coins. Filing damages a coin's value.
How it compares
| Tool | Reads | Best for |
|---|---|---|
| Acid kit | Surface karat range, by which acids dissolve a streak | Jewelry, cheaply |
| Electronic tester | Surface karat, electrochemically | Jewelry, repeatedly |
| Sigma verifier | Resistivity, through the thickness of a coin or bar | Bullion coins and bars |
| XRF analyzer | Exact metals and percentages at the surface | Dealers and assayers |
| Ultrasound | Echoes from inside a bar, which suggest an insert | Large bars |
None of these sees everything, which is why dealers combine them. See what equipment you need.
Sources
- GemOro, AuRACLE PRO quick start guide; U.S. Patent 8,673,126.
- Sigma Metalytics, verifier manual (2026); Evident Scientific, ultrasonic testing of gold bars.
- 16 C.F.R. §23.4 (gold plating thickness).
Equipment: What equipment do you need? · Gold acid test kit · Is my gold real? · All guides
We pay more than pawn shops, jewelers, and mail-in gold kits: in Consumer Reports' tests, jewelers and pawn shops paid 36% to 71% of melt value, and mail-in kits 11% to about 29%. We pay 94% for scrap gold. Who pays the most?
Your gold
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Coins and bullion are verified on arrival, and scrap is paid on the gold recovered after melting. Send photos for a free written estimate.