Usually when unnoticed (undetected) during an inspection or when viewing an image online, sometimes can greatly affect the value of the pieces when compared with an example which is in its original state of preservation.

Here, we see one lower corner that was cleaned up after it was damaged and compared with the sharp, square and diagonal corners... and
though the case with any chip when there is nothing to compare it with, condition does not matter too much.

In shorf; one corner did not become worn while all others did not...

A straight edge taken to the bottom of the plaque will,show you how much shell was taken down in order to remove the damage... and this is one reason why any MOP plaque edge should be placed on a flat surface during inspection (just so you know).