I looked at the scan in Greg's post, then checked the Thomas Day "Monte Carlo" booklet. (FYI, your chip is #6c in the booklet.) The "dents" may have to do with the 2 lunettes embedded in the jeton (just a guess). Over time, these lunettes may shrink or become loose, creating the dents you see. It's hard to tell from the scan. Hold it up to the light, or shine a light through it from the back, and see if these dents correspond to the placement of the 2 lunettes.