First sterilise your jars, by washing and rinsing them, the placing in the oven at 100C for about 20 minutes until they are dry. Leave them in the oven as they should be warm when you fill with the jam.
Wrap the star anise, cloves and cinnamon in a piece of muslin and tie with string
Put the blackberries and the spices in a large pan with 2 tablespoons of water
Cook until soft.
Mash the fruit with the back of a spoon
Remove spices, you can then either leave the berries whole or press them through a sieve or food mill
If you are making the puree, wash the pan then return the blackberry puree to the pan and add the lemon juice. I
Heat, stirring to prevent the blackberries sticking.
If you are using whole berries no need to wash the pan, simply add the lemon juice to the pan and proceed with the following instructions.
Add the warmed sugar stirring until dissolved
Turn up the heat and boil rapidly until the jam has reached the setting point