Rinse berries. Pick out any under ripe or soft berries.
Combine berries and juice or water in a large pot. Bring to a boil and cook over medium heat for about 5-10 minutes, until most of the berries are popped and the sauce starts to feel mushy. Don't cook for more than 10 minutes or you will start to break down the natural pectin in the berries.
Remove from heat and let cool slightly. Working in batches, liquefy sauce in a blender or push through a food mill. Return to pan.
Stir in the pectin until no lumps remain and bring to a boil. Add sugar. Bring it back to a full rolling boil and boil for 1 minute, then remove from heat. If serving immediately, simply pour into a mold or serving container, and refrigerate for at least 2 hours until set.
You can also can this sauce for later use, follow standard instructions for processing and boil in a water bath for 15 minutes for pint jars.