I think a number of pipe makers were using that same "marbleized" imitation ivory in the 1970s and 80s. I can remember one of my students purchasing a brand new set of Kintails around 1976-77 that had the same imitation ivory. I also had for many years a long Naill ABW chanter that dated from about 1979 that had a sole and ferrule of the same material. It was, to my mind at least, a very attractive ivory substitute.