Wash 9 250 ml jars and lids thoroughly with hot, soapy water. Then, sterilize them according to your preferred method (such as boiling or using a dishwasher's sterilize setting). Set the jars and lids aside on a clean towel, keeping them hot until ready to fill.

Wash and clean all the cherries under cold running water. Carefully pit each cherry, discarding the pits. Working in layers, smash the pitted cherries in a large pot until you have 4 1/2 cups of crushed cherries. In my experience, using a potato masher is really effective for this job.

Add the box of Certo regular pectin crystals to the pot with the crushed cherries. Pour in the fresh lemon juice and stir everything together well, ensuring the pectin is evenly dispersed.

Place the pot on the stove over medium-high heat. Add the amaretto liqueur. Stir the mixture frequently as it heats up, making sure it doesn't scorch. When it comes to a rolling boil (lots of bubbles that don't stop when stirred), add all of the granulated sugar at once. Stir and allow the mixture to return to a rolling boil, then boil for exactly 1 more minute while continuing to stir.

Remove the pot from the heat and continue stirring the jam for another 5 minutes to help distribute the fruit and reduce foam. Carefully ladle the hot jam into the prepared hot jars, leaving about 1/4-inch of headspace at the top. Wipe jar rims with a clean, damp cloth, place lids on, and screw the rings on until snug but not overly tight. I recommend working quickly in this step so the jam doesn’t begin to set before being jarred.

Allow the filled jars to cool overnight, undisturbed. The next day, check the seals by pressing down on the center of each lid – if it doesn't pop back, the jar is sealed. Refrigerate any jars that have not properly sealed.