Line 24 muffin tins with cupcake liners. Prepare cupcake batter using cake mix, 1 cup buttermilk, 1/3 cup oil, and 4 eggs. Bake as directed on box. Let cupcakes cool completely. Tint vanilla frosting light pink using icing color. Frost cupcakes with pink icing. Roll edge of each cupcake in crystal sugar.