I still think these are part of a three piece garniture with the tall centrepiece missing - as is so often the case. These are cold enamel decorated on stained milk glass, and have nothing to do with uranium. I have never heard of the concept that two vases should be mirrored to make a set - it is just as likely to have sets which symbolically represent e.g. faith, hope and love, or innocence, truth and constance, or (wait for it) king, queen and knave. Each decorator used his or her own mark on the bottom for the factory administration.