To sterilize jars, submerge clean jars in boiling water for 10 minutes. Jars should remain in hot water until they are ready to be filled. (For more information about sterilizing jars, see Preserving 101.)
5 pounds ripe peaches, chopped
4 cups sugar
1/4 cup fresh lemon juice
Bring a large pot of water to a boil. Fill a large bowl with ice water. Cut an X in bottom of peaches with a paring knife. Add peaches a few at a time to the boiling water and blanch 30 – 45 seconds (depending on ripeness), then remove and transfer peaches immediately to the ice water to stop the cooking. When cool, lift out and peel. The skin should peel back easily from the X.
In a large pot, bring peaches, sugar, and lemon juice to a simmer and then transfer to a bowl. Cover with plastic wrap, and refrigerate overnight.
The following day, bring fruit mixture to a simmer in a large saucepan, skimming foam from surface as necessary. Continue to cook for 15 minutes, stirring occasionally.
To seal and process, fill hot, sterilized jars with hot preserves, leaving 1/4-inch space from rim of jar. Using a clean, damp cloth, wipe rims of jars and cover tightly with sterilized lids and screw bands.
Transfer jars to the rack of a large canning pot filled slightly more than halfway with boiling water, being sure to keep jars upright at all times. Add enough hot water to cover jars by 2 inches. (Jars should be spaced 1 inch apart, and should not touch sides of pot.) Cover pot and bring to a boil. Process jars in gently boiling water for 15 minutes. Remove jars from canner using jar tongs and transfer to a wire rack, and let cool for 24 hours.
Once jars have cooled, test the seal. Press on each lid. If lid pops back, it is not sealed; refrigerate immediately, and use within 1 month. Sealed jars can be stored in a cool, dark place for up to 1 year.