I acquired a set of 4 identical tumblers with thin white stripes. They are heavy pieces and are 4 inches (10 cm) tall. I'm wondering if they are Murano, and if so, one of the better makers (Barovier or Venini?). The quality of these glasses is in my opinion of that level, but I've found nothing quite like them on the net or in my reference books. Any help would be appreciated.