Combine the pomegranate juice and raspberries. Cook over medium heat for about 10 minutes, or until berries are soft and beginning to fall apart. Cool for 10 minutes. Meanwhile, line the bottom and sides of an 8-inch-square pan with parchment paper; coat lightly with neutral-flavored baking spray or oil. Pour the packet of pectin into a small bowl, and set aside near the stovetop.
In a blender or food processor fitted with a steel blade, puree the pomegranate-raspberry mixture. Add 1½ cups sugar and citric acid (if using) to the mixture, and puree briefly. Pour the fruit mixture into a heavy 3-quart saucepan. Cook over low heat, and stir until the sugar is dissolved.
Turn the heat up to medium, and place a candy thermometer on the side of the pan. Stir with a heatproof spatula, occasionally at the beginning, then constantly as the mixture begins to thicken. Bring the mixture up to 230°F. When the mixture reaches 230°F, reduce the heat to hold it there for about 2 minutes, stirring constantly. Add the pectin at once, bring back to a boil, and cook for 1 minute, stirring constantly. Pour the mixture immediately into the prepared pan, and tilt to spread evenly.
Let the jellied fruit rest for 3 hours or up to overnight on a cooling rack. Cut into desired shapes with a knife or cookie cutters. To coat with sugar, toss the candies in the remaining ½ cup sugar. Store in an airtight container at a cool room temperature or in the refrigerator if your house tends to be on the warm side.