my Daddy had a ring that looked a lot like that one, at least from the side-view profile of it (any stamps in his had worn away years ago). it's an emerald cut (fake) ruby in a sort of faked bezel setting (reaaally wide prongs). he got it as a gift from a girlfriend when he was in high school in probably... 1961 or 1962.
not to say that's what you've got or how old it is! i have my Daddy's ring, and i wear it every now and then.
which, i realize, doesn't have much to do with your question. sorry!
that B&F stamp is possibly for Baden & Foss? or at least that's what popped into my head. i seem to recall that they did a lot of synthetic / simulated gemstones in yellow gold. off the top of my head i don't know how old, or new, their stuff is. but that's at least a starting point, maybe?