Wash the cherries and do not stone them (otherwise the cherry stone aroma will be lost). Put the water in a large saucepan and cook for about 10 minutes. Keep mashing the cherries with a potato masher.
Then filter all of the cherry pulp through a gauze diaper or a kitchen towel. Squeeze it out well, you will still get a lot of juice. We then had 2 liters of cherry juice. Boil the cherry juice with 1 kg of sugar and fill into clean bottles.
If you like, you can fill a cherry stone pillow with the cherry stones.