1In a saucepan, combine blackberry juice and lemon juice.
2Sprinkle gelatin over the juice.
3Bring to a slow boil, stirring constantly.
4Once slow boil is maintained, add sugar.
5Cook and stir about one minute to dissolve sugar thoroughly.
6Pour into a bowl and refrigerate until it becomes thicker (syrupy, but not set). Whip cream and vanilla to soft peak stage.
7Gently pour cream into blackberry gelatin mixture.
8Fold/stir gently until an even color is achieved.
9Pour into graham cracker crust