Fine Antique French 16k Gold Frame Brooch and c.1750s Portrait Miniature Jewelry

It seems to me this would be 18k gold, and I can’t quite interpret that French punch on the c-clamp pin back, but it seems like it would be the tiny gold mark and French gold from that period is an 18k standard. That said, it did not test with my 18k acid, but did at 16k. My best guess is it’s just a tiny bit less than .750 (18k). Original slightly convex cover glass, highly polished and without damage. Th portrait miniature is magnificent! A smiling French Nobleman in powder blue suit and ruffled cravat, the rolled powdered wig popular in his day, c.1750-70s, and you can see the outline of the stylish extra large bow in back, holding his ponytail at nape of neck. I do not have an ID for him, and I see no signature. Full measurements are noted on the photos.

Very good to excellent condition throughout. Slight shrinkage of the wafer upon which the portrait is painted, perhaps, as I can see edge around it. Fine gold mount is thick, and the slightly convex polished cover glass is without any damage or losses. Extra long pin, as seen, and a c-clamp. Wear or display,