Modern Mid century design art Pendant. Who made?

I bought this a few weeks ago and hve been searching for the artisan who made this piece. it is sterling silver with a 7 mm by 6 mm amber cab. with 3 vertical gold filled rods that run on top of the sterling circle with the amber cab on top of that. On the back is marked sterling and GF. There is a loop on the back also where the chain runs through but can not be removed. I believe it was made this way because of the size of the loop for the clasp. Now, what I need to know is information on who would have made such a piece and precisely when. Well, within a couple years. It to be a studio piece. But what do I know?.