The early Monte Carlo plaques contained formaldehyde and were chemically unstable. It is very rare to find them in even halfway decent condition. Even many of the common small jetons still sometimes sold on Ebay deteriorate if put in vinyl flips but will fare pretty well in paper envelopes. The ones shown in the Ebay auction you pointed out will have a terrible acrid odor if taken out of the frame, not to mention they will probably crumble if touched. They were undoubted beautiful when originally framed but once encased they just go to heck.