Group of (school?) girls (with teachers?) probably before 1900 possibly in St. Petersburg (Russia) or in Pomerania

This picture was in my (german -> Pomerania) grandmother's box containing old family photos. This one I have never been able to identify. The "x" seems to indicate a girl of which I suppose it could be a family member. The low-quality cardboard/paper on which it is printed and its proportions are completely different from anything else in this collection. In view of this and in view of some dressing-details on the picture, I assume that it might not have been taken in Germany. Since the brother of my grandmother's grandfather emigrated to St. Petersburg (Russia) about 1850, I wonder if this image might be from there. I would estimate the picture's date about 1900 or rather before that. Maybe someone @ AncientFaces recognizes the probable origin of the picture looking at the many details in the girl's dressing, hats, bijouterie?