In the words of Franklin D. Roosevelt: look to Norway. This model is called “Bluebell”, and together with its sister model “Cornflower” it constituted the “Mountainblue” series designed by Willy Johansson (1921-1993) of Hadeland in Norway. It came on the market in 1970 in several sizes, yours being a middle size. It was not rated as art glass, and so not signed. But it’s a nice piece anyway.