I know absolutely nothing about marbles. I bought a box from an estate auction that had a few inside the bottom as if they were special and the kids wanted to play with them. I've never saw a marble that was worth much, but just in case I am wondering if any of these look old or valuable before I give them to the kids to likely lose in the span of 5 minutes lol. The blue one actually looks pretty black until the flash hits it from the camera, and the biggest one has several little nicks or damage.
