Identify maker of pearl necklace?

The short pearl neclace has a silver color clasp. Makers mark
on back looks like either an "F" or "J" in script over a triangular
object. These are surrounded by a circle of pearls; beneath this
makers mark is "s" or "5" inside a box.
Pearls are older but I have no idea if antique.
Thanks to any one who may have an idea who the
maker would be


.