The jetons from Monte Carlo for its chemical composition differ somewhat from color tone (chemical changes with time). Moreover also the comparison of scans of jetons leads to differences caused by different scanners. Only the simultaneous comparison with jetons in hand allows you to see the differences.
Regarding diameters there are differences caused by chemical changes with time. The jetons and plaques (especially plaques) "shrink" with time. Some more than others.
We must understand that there are jetons and plaques of Monte Carlo with nearly a century.