Modernist silver mark crown J

[Lucille]

I've got this really interesting pendant but I've been entirely unable to find out where it's from or who made it despite having pretty clear markings. I'm far from a professional photographer, so the pics are the best I could do. The first mark is a crown with either a J or an F in it with 3 dots below. Next to that is a square with a warped angular hourglass shape or a fat necktie. Don't know what to call it. Under theses is "sterling". Any help would be wonderfully appreciated.