Core the nectarines and plums, cut into small pieces, mix with the preserving sugar in a saucepan and let stand for at least 3-5 hours.
Then slowly heat the pot and add the spices, stir well. When the fruit mixture is boiling, let it boil for 5 minutes and puree about half of it with the cutting stick. There should already be pieces in the jam, then stir in the rum.
Bring to the boil again and then fill into sterilized jars and screw on.