It is a very pretty pastel blue. The book Colors in Cambridge Glass II by the National Cambridge Collectors, Inc. provides some history on this shade – Willow Blue.
The authors state (pg. 50) that the colour was introduced in the summer of 1928. They also comment that “…..may confuse Willow Blue with Moonlight since both are transparent light blues. For the most part they can be distinguished by the blank as there is no overlapping of colors. Pieces from Decagon, Round, 3400 and other 1920s and early to mid-1930s lines will be in Willow Blue, while Moonlight was used primarily with the Caprice and Gyro lines. The one area of overlap was in the Everglade line where early pieces were in Willow Blue and some later production did utilize Moonlight.”
The authors further state that the name Willow Blue was discontinued in the summer of 1933 and then became known as Eleanor Blue.
I also learned that the blue shade called Moonlight is Moonlight NOT Moonlight Blue.