Bring a large pot of water to a boil and carefully submerge peaches for 30 to 60 seconds, then transfer them to an ice bath using a slotted spoon. Once cooled, slip the skins off with your fingers or a paring knife, slice the peaches in half, remove the pit, and roughly chop the flesh into bite-sized pieces.

Place chopped peaches into a large stainless steel pot and add the fresh lemon juice, stirring well to distribute the juice evenly throughout the fruit.

If using powdered pectin, whisk it together with the 1/4 cup of water in a small bowl until no lumps remain. Pour this mixture into the pot with the peaches and lemon juice, stirring constantly for about one minute until everything is well combined.

Add all 3 cups of sugar to the pot and stir constantly over medium heat until every grain dissolves, about 2 minutes. Once sugar is completely dissolved, increase heat to medium-high and bring the mixture to a rolling boil.

Let the mixture boil hard for 15 to 20 minutes, stirring occasionally to prevent scorching. Watch for 220°F on a candy thermometer, or use the wrinkle test: place a small spoonful of hot mixture on a chilled plate, let cool for 30 seconds, then push with your finger. If it wrinkles and doesn't flow back together, you've reached setting point.

Remove the pot from heat and let sit for one minute, then use a slotted spoon to skim off any white or pink foam that has accumulated on the surface. Do a final wrinkle test to confirm the preserve has set to your liking.

While preserves are cooking, run mason jars and lids through the hottest cycle of your dishwasher or hand-wash them in very hot soapy water and rinse well.

Using a ladle and jar funnel, carefully pour the hot preserves into hot jars, leaving about 1/4 inch of headspace at the top. Wipe the rims clean with a damp cloth, place the hot lids on top, and screw on the metal rings finger-tight. Let jars cool at room temperature for at least 12 hours.