Hi Ardy,
I'm not sure what disqualifies this as a perfume or cologne bottle. IMHO it is exactly that. Size-wise, I have a couple even larger, complete with daubers.
The reinforcing ring around the opening does tend to make you think Seguso right away, but other makers made perfume and cologne bottles with the same feature. I have one with a partial plain paper "made in Italy" label along with a Balboa import label, and even one with a generic Murano label.
Is it the fit of the stopper that you are referring to when you mention execution? From the photo the fluted ball appears to sit right down on the ring(making full contact), versus hovering just above the ring if the grind to the stopper neck were more precise. The stopper(with dauber) on the bottle with the Balboa label fits the same way.
I have noticed that Seguso perfumes from the 50's are alot rougher and less precise when it comes to the grind on the stopper/dauber versus those from the 60's.