Black Onyx Cameo Set - FAB

by Jeffery Masters
(Albemarle NC USA)

my mother passed 3 yrs ago and i got a cameo set of ear rings and necklace black seting with white female on all 3. On the outside of setting looks like brown stones all around it and on back it reads 925 FAB.

what do I have and what does FAB mean? is it antique or modern and what is all the materials used.