It's not two pieces joined, although I see how it gives the appearance. The bullicante (air bubbles) aren't really as "irregular" in spacing so much as size; they're oblong (not round), sort of like grains of oats. Looking at a Barbini lamp I own, they're really not that different in shape. I'm tending towards Barbini now, although this would be an "attribution" at best until a catalog picture or labeled piece is located. It actually is a high quality piece, which leads me to think it's by a "better" producer. Although I based on further researches and these posts my initial hunch that it's an Archimede Seguso or Barovier is placed in doubt. As mentioned, there was an matching bowl that I declined to buy. The fact that it was produced as part of a set alone makes me highly doubt it's a recent re-interpretation, i.e., 1980s or later. I do think it's circa 1950s, despite a lack of significant base wear.