I am not sure why this recipe asks for demerara or turbinado sugars. I have made this recipe successfully for years with powdered sugar. A previous comment (Juliet) correctly states that the other sugars are slightly tan, so why the designation? Use powdered sugar and you will get the best color contrast which makes these attractive as well as tasty!
Glad I'm not the only 1 puzzled by this recipe - powdered sugar (not demerara or turbinado) is what I've used for years as well - although, I found that if I roll in granulated sugar , THEN roll in powdered sugar, the powdered sugar doesn't 'melt' into the dough so easily for a better 'snowy' effect.
& what's up w/ the 2 different sizes, anyway?