Edge chips, delaminating, and other record anomalies.  Wyatt Markus

I do not have any defectrive records to take pics of, for examples, but can describe to you the following Diamond Disc conditions:

Edge chips:   Edge chips can certainly be worked around, as long as they do not interfere with the actual recording surface itself.  
Simply, lower the stylus near the recording, and AVOID lowering the stylus onto or into the path of a chip.  The roughness of an edge chip
will immediately shear off the finely shaped diamond stylus tip!  A sheared diamond will actually machine the surface of your records like
a lathe.  

Delaminating and warping:  The condensite laminate on the earlier records (1913-1915-ish) tends to peel away easily, and can expose sharp edges in the
recording surface that can harm the delicate diamond stylus tip.   This can include splits, pitting, and deep grooves.  This condition often occurs
after te record has absorbed some moisture, and the inner core swells and warps from the moisture imbalance.  These records, frankly, can only be
thrown out, and not saved.  It isn't worth wasting a $95 stylus on.