The goal is not home certification. The goal is to catch obvious failures quickly, then know when the remaining uncertainty requires an expert.
The four tools
- 0.01 g digital scale: calibrate it, tare holders, weigh twice.
- Digital calipers: zero every session and measure diameter in millimeters at two rotations.
- Small neodymium magnet: a coin that sticks fails; a pass proves nothing.
- 10× triplet loupe: use low, raking light to inspect fields, devices, rim, and both sides.
The order matters
- Check the deal: price, seller, return rights.
- Run weight, dimensions, and magnet.
- Read the surfaces under a loupe.
- Escalate key dates, gold, and serious money to recognized experts or established grading services.
Screening, not certification: a non-magnetic coin with the right weight can still be counterfeit, altered, or cleaned.