Never say never of course but I have yet to come across an Argy-Rousseau which was not pāte de verre. The signature does not convince me either. Cold enamel decoration which rubs off easily is not likely to have been used by Daum, B&S or Meisenthal. The decoration seems to have been done in post production. And another thought - if you have gold available, why use it only on the underside and not on the decoration?
Did we say welcome to the Glass Message Board by the way? If not, welcome to the board!