Abalone often has imperfections or holes. I'm not exactly sure what causes them but my assumption has always been that they are caused by parasites that bore into the shell. Usually the maker/builder will select out these imperfections, however, my father has a late sixties knock-off, or copy, of a gibson hummingbird with
abalone inlays in the fretboard that have holes. It's only in about two or three of the pieces and has no efect on playability. It's a natural occurance
.
