"but I think could detect most signs of repairs"

Sorry to say this but I doubt your microscope would detect even a small proportion of alterations.

In most cases, we are talking about chips where a cancellation hole through the inlay has been filled and the inlays replaced with those from another chip, or with newly made ones.

We know that an xray will detect this type of repair if the material used to fill the hole is of a different density than the rest of the chip.

If the hole has been filled with clay, regardless of whether it was through the inlay or in the mold, we dont even know yet if the xray will work.

How would you detect a fake brass core with either method?

I will post some pics shortly.