Inspect four pint-sized jars for cracks and rings for rust, discarding any defective ones. Immerse in simmering water for at least 5 minutes or until jam is ready. Wash new, unused lids and rings in warm soapy water.

At the same time, bring peaches, ginger, and pectin to a boil in a large saucepan over medium heat. Add sugar and butter; cook and stir until sugar is dissolved. Stir constantly and return to a boil, about 1 minute. Remove from the heat and skim off any foam with a spoon.

Pack peach mixture into hot, sterilized jars, filling to within 1/4 inch of the top. Run a clean knife or thin spatula around the insides of the jars to remove any air bubbles. Wipe the rims with a moist paper towel to remove any residue. Top with lids and screw rings on tightly.

Place a rack into the bottom of a large stockpot and fill halfway with water. Bring to a boil over high heat, then carefully lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring to a rolling boil, cover, and process for 10 minutes.

Remove the jars from the stockpot and let rest on a cloth-covered or wood surface, several inches apart, until cool.

Once cool, press the top of each lid with a finger, ensuring that the seal is tight and the lid does not move up or down at all. Store in a cool, dark area.