Blancpain

I recently bought a watch on ebay that the seller advertised as a Blancpain watch. What I received was a 14kt gold case, but it was not marked in any way as Blancpain, the dial was not marked, and the crown was obviously not Blancpain. The case is square inside it is marked KO 14k # 300384 . The Blancpain movement is a round seventeen jewel manual wind with no cal.#. The watch appears to be 40's-50's  vintage.  My question is, did Blancpain sell movements to other watch manufacturers for them to produce or, did they ever  produce a watch such as the one I have described? Would a watch such as this be concidered a Blancpain watch since it has a Blancpain movement only. Any help would be appreciated. Sincerely: Ronald

 

but yes, Blancpain delivered movements to other companies, and even produced watches under different names.

Magnus