Mother of pearl was used in snuff boxes in three main ways. Neither use is necessarily more valuable than another. The most common use of mother of pearl was to be set under gold cage work.
Several goldsmiths, especially in France, would use mother of pearl as an inlay. The snuff box shown below has mother of pearl inserts for the faces of the people.
The rarest and most intriguing use of mother of pearl is as a carved insert. The snuff box below is solely made out of mother of pearl. The artist actually carved a scene into the insert.
We consider mother of pearl snuff boxes to be a specialty of ours. If you have a box you need help with, then just ask. We would be happy to help.