Ivo,
I could not locate the shape in my Steuben book, although because it is clear, if Steuben, it would most likely be a later piece, post 1933 after colors were discontinued and phased out.
IMHO it does not strike me as Steuben, as their claim to fame is the use of 10M, an exceptionally clear glass, and the use of so much frost on the surface does not strike me as their style... They engraved quite a bit, but I could find no images in my book showing that style of frost being used. I can not think of seeing a piece of this style either. The post color era used some Carder era shapes, and also introduced some new shapes. This form is, IMO a little "stiff" in feel for them.
Is there a pontil on the underside?, or flat ground base?
Craig