Prepare the peaches: Wash, peel, and slice the peaches into 1/2-inch thick pieces. Blanching in boiling water for 30 seconds then immediately plunging into ice water helps with peeling.

Combine ingredients: In a large saucepan, combine the peaches, sugar, and lemon juice. Stir well.

Add pectin: Stir in the liquid pectin. Bring the mixture to a rolling boil over high heat, stirring constantly. A rolling boil is a boil that cannot be stirred down.

Boil for 1 minute: Once at a rolling boil, boil hard for exactly 1 minute, stirring constantly.

Remove from heat and skim: Remove from heat and skim off any foam.

Ladle into jars: Ladle the hot jam into sterilized half-pint jars, leaving 1/4-inch headspace. Wipe the rims clean.

Seal jars: Place lids and rings on jars and tighten fingertip tight. For longer shelf life, process in a boiling water bath for 10 minutes (adjust for altitude).

Cool and check seals: Let cool completely. Sealed jars will have a concave lid. Store sealed jars in a cool, dark place. Refrigerate unprocessed jars and use within 2-3 weeks.