Make the pomegranate gelatin: Place a 5-cup mold in the refrigerator to chill. In a saucepan, sprinkle gelatin over 1/2 cup pomegranate juice, and let soften 5 minutes. Cook over medium-low heat, stirring, just until gelatin is dissolved; do not let boil. Remove from heat and let cool completely. Stir in remaining 1 cup pomegranate juice, then pour into chilled mold. Skim off foam from surface, and refrigerate until partially set, 1 to 1 1/2 hours.
Meanwhile, make the cranberry gelatin: In a saucepan, simmer cranberries, sugar, and 1 2/3 cups water until berries have burst and mixture has thickened slightly, about 15 minutes. Strain through a fine sieve into a bowl, pressing on solids to extract as much liquid as possible, and scraping pulp from bottom of sieve into liquid. Discard solids. You should have about 1 3/4 cups liquid.
In a small saucepan, sprinkle gelatin over remaining 1/4 cup cold water, and let soften 5 minutes. Add about 1/2 cup of strained cranberry liquid to softened gelatin, and cook over medium heat, stirring, until gelatin is dissolved; do not let boil. Let cool completely, then stir gelatin mixture into remaining cranberry liquid in a bowl.
To assemble: Cut peel and pith from clementines, then cut segments free from membranes. Gently blot segments dry with paper towels. Press half of clementine segments into pomegranate layer, and gently pour cranberry gelatin on top. Refrigerate until cranberry gelatin is almost set, about 1 hour.
Make the cranberry sauce: In a small bowl, sprinkle gelatin over 3 tablespoons orange juice, and set aside to soften.
Bring remaining orange juice, the cinnamon stick, sugar, and lemon peel to a simmer in a large saucepan. Cook, stirring, until sugar dissolves, about 3 minutes. Add cranberries and cook, stirring occasionally, until berries have burst and mixture has thickened slightly, about 12 minutes. Remove from heat, and add gelatin mixture, stirring to dissolve. Transfer cranberry sauce to a bowl to cool.
Press remaining clementine segments into cranberry gelatin and gently top with cranberry sauce, spreading evenly in mold. Cover mold and refrigerate 1 day, or up to 3 days.
To serve, dip bottom of mold in a bowl of hot water 10 to 20 seconds, then invert onto a cake stand or serving plate, and carefully remove mold.