It's more likely etched than sandblasted. It would have been easy to mark straight lines around the glass, dip the bowl and stem in wax up to the lines, and etch the wide band. Dealing with details (e.g. curved areas, the raised line at the top of the etched area) would have added labor; the top area was small enough that it was easier to grind it by hand. That's my guess, anyway.
...hmm. I wonder whether the proud thin band was made with resist, and the etched area actually went beyond it. It's very sharply delineated both top and bottom - but not actually smooth. The wax dip would not have to be precise, since the boundary of the etch was smoothed by wheel grinding.
Very nice example of the techniques used together. Great shape.