A few tenths of a gram can separate compositions, but scale drift, dirt, holders, and tolerance can mislead.
The practical lesson
Start with the complete coin and a neutral description. Record weight, diameter, edge, both faces, lighting, and the proposed production mechanism. Then compare damage and ordinary varieties before assigning rarity.
Why collectors get trapped
Error coins are visually exciting, and online marketplaces reward dramatic titles. That combination encourages conclusions before evidence. A better habit is to make the coin pass a series of disproof tests.
What to save
- Original photographs
- Scale and caliper readings
- Seller description
- Certification lookup
- Sources checked
- Exact sold comparables
Uncertainty is not failure. “Unresolved” is a better collection label than a confident but physically impossible error name.