
I can't enlarge your pics, I'm afraid, so I can't see if there are marks on the bottom., but there is something that looks like a date (200something-faint at about 12 o'clock on the middle pic, and some scratches which may or may not read someting , or be remains of a label or glue, at about quarter past.

Would you try rubbing some talc or cinnamon or cocoa powder over the marks and see if they photograph any better?