Erkki Vesanto did not work for Iittala. (His main work is from Riihimäen Lasi, which this is not from)
I went through the book about his work published for the exhibition in 2012 at the Finnish Glass Museum and could not find anything quite similar, and not even one picture of an engraved object designed my him. But the text says: "Siiroinen collaborated for approximately ten years with Studiolasi. In addition to design work he participated in displays of products in department stores and signed Studiolasi products.... Siiroinen was also a skilled engraver and would occasionally decorate his glasses himself"
I can also find that Studiolasi products were numbered in that way (later figure tells the height). Studiolasi Oy was founded in 1977.
Just to be sure, one couldn't...: as they mention: "In addition to working for Studiolasi, Siiroinen is known to have designed at least for the Napapiirin Taidelasi company i n1985. There is no information, however, on the designed objects. Siiroinen also collaborated with Jaakko Liikanen's JL-lasi company in the mid-1990s." So in theory it could be either of these too.
I am just suggesting, sorry, I want to add I have never seen even a picture of a similar vase so I cannot confirm anything.