since the French were noted for their Opaline, then might this be in that direction. Is the base just flat, or is there a pontil (snapped or ground), and is there much of a wear ring on the underside of the base. Of course it might just be a recent piece of 'touristy' type of glass. What is the height - it is difficult to assess from the picture. Mind you none of this gives us the maker unfortunately
