Peel and core the nectarines and place in a saucepan. Pour hot water over the peaches for better processing. The skin can then be peeled off without any problems. Also remove the seeds and add to the saucepan.
Puree the fruits and mix with the preserving sugar. The pot should not be more than half full to prevent it from boiling over.
Bring the fruit puree to a boil over high heat, stirring, until all of the contents are bubbling. Cook for 4 minutes while stirring.