Step 1: Prepare your water bath canner by filling it with water and bringing it to a simmer. Wash and sterilize 6 half-pint jars and keep them warm in the water.
Step 2: Blanch the peaches in boiling water for 45 seconds, then shock in ice water to easily remove the skins. Pit and finely chop the fruit.
Step 3: In a large 6-8 quart saucepan, combine the chopped peaches, lemon juice, and pectin. Stir well until the pectin is dissolved.
Step 4: Bring the peach mixture to a full rolling boil over high heat, stirring constantly so it does not burn on the bottom.
Step 5: Stir in the sugar all at once. Return the mixture to a full rolling boil and boil hard for exactly 1 minute, stirring constantly.
Step 6: Remove the pot from the heat. Skim off any foam with a metal spoon. Ladle the hot jam into the prepared jars, leaving 1/4 inch of headspace.
Step 7: Wipe the jar rims with a clean, damp cloth. Apply lids and bands. Process in the boiling water bath canner for 10 minutes. Remove and let cool for 24 hours without moving.