Decorate cookies. Using spatula, ice cookies smooth with white icing.
Prepare four decorating bags separately with deep turquoise, turquoise, medium green and mint green icing. Cut small tip in each bag.
Starting with deep turquoise, pipe line down center of cookie. Repeat with turquoise, piping line on each side of deep turquoise line. Continue with medium green and mint green icing. Using spatula, swipe colors, alternating going from top to bottom and bottom to top. For best results, clean off spatula after each swipe.