If you like, garnish the jellies with a dollop of sweetened whipped cream and a few pureed raspberries.
Prepare 8 Champagne flutes with fruit. Arrange raspberries, strawberries and blackberries in each flute.
Bring water and sugar up to a simmer. Once sugar has dissolved, add sliced peach and lemon zest and simmer for 3 minutes. Remove peach, peeling off skin if it comes off easily and place a slice in each flute.
Pour ½ cup of champagne over gelatin to soften for a minute. Stir softened gelatin into warm sugar syrup and return to heat to dissolve. Allow to cool to room temperature. Stir in remaining Champagne. While still bubbly, ladle Champagne mixture slowly over fruits, stopping at top of fruits. Chill flutes until jelly is almost set, then top with remaining Champagne mixture. Chill for at least 3 hours before serving.
Garnish each flute with a slice of peach and a sprig of mint.