Who is the Maker of this Modernist 18K Pendant?

by Janet
(Atlanta)

The top of the bail is stamped 750 with a maker's mark that has two triangles on their sides with the top points touching (so that it looks a little like a bow). The left triangle has a "P" mark and the right triangle has an "F" mark. Can you tell me who made it, where and about when? Also, any ideas as to value?