Thanks David, you are absolutely right; it just felt a little odd knowing that Gunnel Nyman died already in 1948 (at the age of only 39 years).
The Serpentiini / Streamer GN 18 vase was designed in 1947, and has been presented in Nuutajärvi catalogues in 1949-1958. Should have checked my "Gunnel Nyman - Beauty Captured in Glass" book first!