1. In a medium saucepan, combine the raspberries with the water and cook over moderately high heat, crushing the berries with a potato masher or a fork, until very juicy, 5 to 6 minutes. Pour the hot berries into a fine stainless-steel sieve set over a medium bowl and let drain.
2. Gently stir the berry mixture, scraping it up from the bottom of the sieve with a spatula; don't press on the solids or the gelatin will be cloudy. You should have 2 cups of juice. Stir in the sugar until dissolved and let cool.
3. Transfer 1/4 cup of the raspberry juice to a small bowl. Sprinkle the gelatin over the juice and let stand until the gelatin is evenly moistened.
4. In a small skillet, warm the gelatin mixture over moderate heat just until the gelatin melts. Stir the mixture into the remaining raspberry juice in the medium bowl and pour it into 6 wineglasses. Refrigerate until barely set, about 1 hour. Gently stir in the fruit and refrigerate until firm, about 1 hour longer. Garnish with whipped cream.