I have a Tudor Ceramic and occasionally see small marks from the spring bars after changing straps. As others have noted, they are typically steel bits from the spring bars that can be wiped off the watch without any evidence of a scratch. Pencil eraser should work.
to my understanding, omegas ceramic back cases are full ceramic, and at first i thought it is a chop off issue, so even if ot is chopped, it should be black. right?