Error Coin Questions?
Do you have a coin that looks like it might be an error and you don't know how it could have happened? For a robust discussion of your error coins and to learn more, I recommend posting well-focused pictures of your error coins on the following online forum dedicated exclusively to discussing mint errors:
Be sure to post specific questions and state what you think the error is. Please do NOT send such questions to email@example.com. That email is for buy/sell business for the store, and not general error questions.
Here is a link to an awesome resource that explains and gives examples of just about every type of mint error there is and also explains some types of damage that may cause a coin to look as if it was a mint error: http://www.error-ref.com/
Here is a link that explains the difference between valuable die errors such as doubled dies, and other forms of doubling that are more common and not valuable such as "machine doubling" or "strike doubling":
Strike Doubling Flyer.pdf
I also recommend buying the book "Strike It Rich With Pocket Change" by Ken Potter. That is a great reference to use how to find valuable error and variety coins and distinguish them from more common errors and damage. World's Greatest Mint Errors by Mike Byers and 100 Greatest Errors are also interesting books about errors and the minting process.
I also recommend joining CONECA, the national error coin club: http://www.conecaonline.org/ (be sure to mention Jim Essence recommended you).
Here is a great free online magazine dedicated to mint errors: http://www.minterrornews.com
From these groups you will learn a lot and meet other error enthusiasts.
Best wishes and have fun!