How to Identify Varieties and Errors of Coins Quick Answer To identify a coin variety or error, examine the coin under 5x–10x magnification and compare it to a standard example of the same date and mint mark. Varieties are differences caused by changes to the die itself, such as a repunched mint mark or a doubled die. Errors are mistakes made during the minting process, such as an off-center strike or a wrong planchet. Weigh the coin, check for true doubling versus common "machine doubling," rule out damage that happened after the coin left the mint, and compare any suspected find to a...