Peach Jam

I tried making peach jam for the first time this year and it turned out so good! I used the recipe that comes in the SureJell package...

4 c. finely chopped peaches (I diced mine, then used a potato masher for less chunks.)
2 Tbl. lemon juice
5 1/2 c. sugar
1/2 tsp. butter

Measure sugar into a bowl and set aside. Measure peaches and put into a sauce pan with lemon juice. Stir 1 box pectin into fruit. Add 1/2 tsp. butter to reduce foaming. Bring mixture to a full rolling boil, stirring constantly. Stir in sugar quickly. Return to a full rolling boil and boil exactly 1 minute, stirring constantly. Remove from heat and skim off any foam. Ladle quickly into prepared jars, filling to within 1/8 inch of tops. Wipe jar rims and threads. I process mine in a steamer for 10 minutes (time starting after there's a steady stream of steam). Let stand at room temperature for 24 hours. Store unopened in a cool, dry, dark place up to 1 year. Refrigerate opened jars up to 3 weeks.