Wash the fruits, remove their pits and halve them. Heat the sugar with 4-5 cups water and boil on low heat until sugar dissolves completely and you obtain a sugar syrup.
Pour 1/2 the syrup over the fruits and boil them on low heat about 1 hour. Let the mixture sit for at least 6-8 hours, then add the remaining syrup and boil to the desired thickness.
Distribute the syrup into dry jars, close them and flip over while still hot.