Hello. I have this interesting piece and I can't identify this maker. Unfortunately, this is the best stamp that I have found. To me, it looks like FF, EE, FE, EF. In the middle, it could be a face or a sun, because over it looks like sun rays. Thank you in advance.
I would suggest to clean a bit the lozenge mark, in order to :
- have a better view of the "different" between the two letters (the symbol may be a plain sun with its ray, indeed)
- to ensure that the second letter (that may well be an "F") is not followed by small "RE" or "RES", thus being a common abbrevation for "frère" or "frères" (= "brothers")