Puree the raspberries with a hand blender.
Mix the berry puree in a saucepan with the preserving sugar and lemon juice. Bring the mixture to the boil and boil for approx. 4 minutes until bubbling. Then make a jelly test.
Immediately pour the hot jam into jars and seal them.
Preparation Tip:
If desired, you can refine the jam with a little rum.