Prepare your jars, lids, and rings by washing with warm, soapy water. Place the lids in a small saucepot to simmer. Fill a water bath canner half full of water and bring to a boil.
Wash cherries and remove stems. Pit the cherries by pressing the flat edge of a knife in the center (or you can use a cherry pitter. I highly recommend using a sheet pan to catch the juice, as this job gets pretty messy!
Finely chop or grind cherries (a food processor works best). Put four cups of the prepared mixture into a saucepan. Add lemon juice and pectin. Bring to a full rolling boil, stirring constantly. Stir in sugar and almond extract, and return to boil for exactly one minutes, stirring constantly. Skim foam if necessary.
Ladle into clean jars, leaving ¼” headspace. Wipe rims with a clean, wet cloth and place warm lids on top. Tighten rings. Submerge the jars into the water bath canner. There must be 1”-2” of water over the tops of the jars. If there is less, add more boiling water.
Bring the water to a boil. Once it reaches the boiling point, process the jars for 10 minutes.
Remove from water and place on a towel to cool. After they have cooled, check to make sure the jars have sealed by pressing gently in the center of each lid. There should be no spring to the lid. If there is, reprocess immediately or refrigerate.