Peel and chop peaches.
Toss chopped peaches in lemon juice to prevent browning.
Place the peaches and lemon juice in a deep, heavy-bottomed saucepan.
Add the pectin (but not the sugar) and bring the mixture to a boil. Cook 2-3 minutes, mashing the peaches for a smoother preserve or leaving them whole for a chunky peach jam.
Add the sugar and stir to incorporate. Return the pot to a boil and cook for 1 minute, stirring to distribute heat.
Turn off the heat and ladle the finished peach jam into jars, leaving ¼ inch headspace. Cap with 2 part lids.
