It's possible.
A while back, I had an old frilly edged uranium plate with extra shaping like this, (I think it eventually went to Pamela's Museum
) and I found out that the extra shaping was done after the frills, by slumping. It was an extra bit of work carried out for each individual piece, to get the big dips and humps. But it was just the one colour of glass.
To find out if there is clear casing over the body, try looking at the very edge of the base, with a light source behind it. (I use the strong lights over the kitchen hob) Wiggle it around a bit to see if you can make anything out on the outside.
With the wiggling, try to find a way of seeing the very surface from the side on - so it appears thicker.