How to Make It
Stir together orange-flavored gelatin, 1 envelope unflavored gelatin, and 1 1/2 cups boiling water until gelatin dissolves. Pour into an 8-inch square pan. Repeat with lime- and strawberry-flavored gelatins, placing each mixture in its own pan. Chill pans until firm.
Run a small knife around outer edge of each pan. Cut chilled gelatin into 1/2-inch squares. Dip bottom of pans in warm water for 10 seconds. Unmold gelatin squares onto a jelly-roll pan. Chill until ready to use (up to 24 hours).
Preheat oven to 350°. Stir together graham cracker crumbs, butter, and 1/4 cup sugar. Press into bottom of a 10-inch springform pan, and bake 10 minutes. Cool completely (about 20 minutes).
Meanwhile, sprinkle remaining 1 envelope unflavored gelatin over 1/4 cup cold water. Microwave pineapple juice in a microwave-safe bowl at HIGH 1 minute or until hot. Add hot pineapple juice to gelatin mixture, and stir until gelatin dissolves. Chill until consistency of unbeaten egg whites (20 to 30 minutes).
Beat cream, vanilla, and remaining 1/2 cup sugar until stiff peaks form. Fold in pineapple mixture until blended.
Gently fold three-fourths of gelatin squares into pineapple mixture; pour over crust in pan. Tap pan sharply on counter to remove air bubbles. Top with remaining gelatin. Tap on counter again. Cover and chill 12 hours.
Run a small knife around edge of pan, before unlocking sides, to break seal. Remove sides of pan before serving.