Start by sterilising your jars and placing saucers into the freezer (see instructions in notes below).
Put chopped nectarines, lemon juice, water and granulated sugar into a preserving pan or similar.
Place the pan over a low heat to gently dissolve the sugar. Stir with a wooden spoon until the sugar dissolves completely. Do not allow mixture to simmer.
Once the sugar has dissolved (listen out for any crunching against the spoon) turn the heat up high and bring the mixture to a rolling boil. Time for 10 minutes, stirring continuously. (Alternatively, if you have a digital thermometer boil until a temperature of 105°C or 221°F is reached.
Remove from heat and test for set by placing a few drops of jam on a chilled saucer and place in fridge for 30 seconds.
Push a finger through the jam and if it forms gentle crinkles and is gel like then it has reached setting point. If setting point hasn’t been reached then bring the jam back to a rolling boil for 2 minutes. Repeat steps as necessary until setting point is reached.
Use a potato masher to crush nectarine chunks to desired consistency.
Push any scum that’s formed over to one side and skim off with a large metal spoon
Pot up the hot jam into hot sterilised jars using a ladle and jam funnel.
Screw on lids immediately.
Allow to cool completely before serving. (See post above for storage information).
Makes approximately 4 x 240 ml jars of jam.