Beautiful pie, you'll love it!! If blackberries are not available, use 3 cups each of raspberries and blueberries. When pureeing the berries, be sure to process them for a full minute; otherwise, the yield on the puree may be too small. Apple jelly can be substituted if red currant jelly is unavailable. If you have a salad spinner, line the basket with paper towels, add the berries, and spin until dry.