A French 20th Century Louis XIII style frame, these mottled finishes are often called 'Impressionist' which may not be the best or most accurate description but it has become part of framing style vocabulary. Lovely thin mitre splines though!
In a similar way to how any black and gold frames, especially those used on antique prints, are simply called 'Hogarth frames'. They have little in common with real Hogarth frames which are really quite lovely polished fruit wood mouldings, often with a gilded sanded panel and carved edge.
