Found this in the first mint set I opened. I first thought it was just a scratch. Did a quick scan because I was too lazy to image just one coin. First time I have ever found a crack as large as this in a mint set. Just found it interesting. I'll get a real image sometime soon. I'll bet there are many of these out there.
A different site tells me this is a strike thru. Not sure I understand. The metal is raised along what I'm calling a crack.