Antique Filigree Bow Brooch Large Size

Beautiful, very intricate filigree work. This is lightweight….seemingly gilt over brass. There is a mark along the edge of the clasp but I can’t make sense of it. 3” wide 2 &1/2” long Condition is very good for age and material: The back has a couple red spots that could be something like nail polish transfer. Not seen from the front though.