Drain cherries and pineapple, reserving juices. Set fruit aside. Add enough water to combined juices to make 3-1/4 cups; pour into a saucepan. Add sugar; bring to a boil. Remove from the heat; stir in gelatin until dissolved. Add cherries, pineapple and ginger ale. Chill until partially set. Stir in coconut and nuts if desired. Pour into an oiled 3-qt. mold or 13-in. x 9-in. pan. Chill until firm, about 3 hours.