For this manicure, you'll need a white, black, and matte top-coat nail polish, plus a mini sponge (just cut one up if you don't have any small ones on hand). Start by painting on a rough circle using a small paint brush, then dab on white polish and go in with the black shade to create this full-moon effect. To finish, paint over the entire design (once it's completely dry) with a matte top coat.