Identifying Antique Brooch: Maker's Mark & Stone Identification

Question
Hi there is a brooch advertised on ebay with looks like goldtone rope style setting with a amber stone and darker down one side with marking c757 on back is this the makers marking on metal also what would stone be thanks rhonda

Answer
The c757 sounds like some sort of a model code...
although I don't know... determining exactly what the stone is is really impossible unless it is examined by a gemologist...
and most likely better first-hand... I would really not trust what they say on eBay... they may not know either... and there are literally dozens of amber colored stones.
regards Rolfe