(New poster here) Are there any elements to look for when checking the authenticity of the errors in the subject? I worry about clipped planchet coins which seem easy to, well, clip. I also get nervous about highly off center pieces since there is less of a design to examine. What should I look for to check if the coin is authentic?
There is good information on the authenticity of clipped planchets here: http://error-ref.com/_Curved_clips_.html.
All of the above suggests are good, but if you're ever still suspicious of a coin's authenticity, just post a few pics here and we'll give you our opinion... I know of at least two error-coin experts on these forums, so their opinions are the ones you'd really be interested in hearing.