At least 1 day before serving, arrange red and green cherries in clusters in a ring mold that fits into your punch bowl. Add water to just cover cherries. Freeze for about 2 hours or until firm. Add more water to fill ring. Freeze. (If you don't have a punch bowl, freeze cherries in ice cube trays to float in a pitcher or individual glasses or cups.)
In a large heat proof pitcher or bowl, dissolve gelatin in boiling water. Add the lemonade concentrate, stirring to melt. Add the cranberry juice and the 3 cups water. Cover and chill.
Remove ice ring from mold by running warm water over it. Place in punch bowl, cherry side up. Pour punch mixture over ice. Slowly pour in ginger ale. Makes about 13 cups (20 to 24 servings).