coin in cello from a mint set and noticed this assuming a scratch. and a big one. keep it in the cello or remove for a much better look
It's a common place for a die crack on Washington quarters. Browse thru Heritage archives and I bet you'll find a bunch of them.
Die Break or crack, leave it in the cello, especially if it is a complete set. An error coin in a set would be worth more. Thanks for sharing, good luck.