Combine prepared fruit with lemon juice in a 6 or 8 quart saucepan. Gradually stir in Fruit Pectin. Add up to 1/2 teaspoon butter or margarine to reduce foaming, if desired. Bring mixture to a full rolling boil that cannot be stirred down, over high heat, stirring constantly.
Add entire meaure of sugar, at once, stirring to dissolve. Return mixture to a full rolling boil. Boil hard 1 minute, stirring constantly. Remove from heat. Skim foam if necessary. Add cinnamon and gently stir.
Ladle hot jam into hot jars, one at a time leaving 1/4 inch headspace. Clean rim and threads of jars using a clean, damp cloth ot remove any residue.
Process in Water Bath for 10 minutes. After processing is complete, turn off heat and remove lid. Let jars stand for 5 minutes.
Remove jars from canner and set upright on a towel to cool, undisturbed, for 12 to 24 hours. Bands should not be retightened as this may interfere with the sealing process. After cooling test seals by pressing the center of each lid. If a lid does not flex up and down, it is sealed! If a lid is not sealed within 24 hours, refrigerate immediately for up to 3 weeks or reprocess for thte full lenght of time using a new lid.