In a saucepan over medium heat, combine the pomegranate juice and sugar. Stir continuously until the sugar fully dissolves and the mixture is warm but not boiling.

Sprinkle the gelatin evenly over the cold water in a small bowl and let it bloom for about 5 minutes. Then gently heat the gelatin mixture, stirring until it dissolves completely without boiling.

Stir the dissolved gelatin into the warm pomegranate juice mixture until fully incorporated. Add the vanilla extract and mix well, then remove from heat and let it cool slightly.

In a separate bowl, whip the heavy cream until soft peaks form. Set aside carefully to maintain the airiness.

In another clean bowl, beat the egg whites until stiff peaks form, ensuring they are firm and glossy for the perfect mousse texture.

Gently fold the cooled pomegranate mixture into the whipped cream, incorporating without deflating the cream. Then carefully fold in the beaten egg whites until smooth and homogenous.

Pour the combined mousse mixture into a dome-shaped mold. Refrigerate for at least 4 hours, or until fully set and firm to the touch.

Once set, carefully unmold the mousse by loosening the edges and inverting onto a serving plate. Serve chilled as a gorgeous, refreshing dessert.