This collie is Crystal Opal Satin – clear glass with a satin finish and transluscent white “opal” on the ear tips, nose, feet and tail.
In addition to the popular clear glass version, Mosser Glass produced Crystal collies in carnival, satin and opal, as well as various combinations of them, like this one. Crystal and crystal carnival are not too difficult to find, the other variations don’t show up for sale very often.