Step by step
Pit the cherries. Put them in a Food Processor fitted with the Multipurpose Blade and pulse a few times to chop the cherries into big pieces.
Put the cherries in a saucepan. Add the lemon juice. Place the saucepan over medium heat and bring to a boil.
Add jam sugar, bring to boil and cook for another 5 minutes, stirring regularly.
Pour the hot jam into clean jars, close them and turn upside down until cooled down completely.