Charles' post mentioned some things to look for and I can easilly think of some others depending on the manufacture; such as perhaps seeing if an inlay was placed back in its recess free of any residual remaining that might cause an uneveness noticed like a grain of sand under a postage stamp (or more convex vs. concave; again, depending on manufacture) while a straigt edge is held over the inlay... or look for a break in any litho process that might become evident (under light) in a peeling-back process... or feel for any voids (air pockets) between the inlay and slug by perhaps tapping several areas of the inlay surface (or applying pressure with the finger while feeling for sponginess) with the fingernal or a metal instument and even listening for a hollowness which might alert (a signal) that the inlay wasn't applied under pressure as it would have been while in its original state (pre-alteration)... and I'm also quite sure there are other methods of alteration detection known within our community/membership.

My coffee buzzer is calling me...