• If using frozen berries, allow them to defrost in a saucepan.
• If using the wrinkle test for the setting point, place a couple of side plates in the freezer.
  
• Put your jam jars in a small roasting dish in the oven to sterilize at 100°C/220°F/Gas Mark 1 while you make the jam.
• Place the fruit in a large saucepan. Simmer gently until soft. If using fresh fruit, add a splash of water. (Frozen berries will be wet enough to use without adding any.)
• Once the fruit is soft, add the sugar and lemon juice. Simmer the mixture to dissolve the sugar. Keep stirring.
• Once all the sugar has dissolved, turn up the hob and heat the jam quickly to a rolling boil. After a couple of minutes, start testing the jam's set using your favourite method.

Testing for set

• Temperature: Use a jam thermometer, and check to see that the jam has reached 105°C/221°F. 
• Wrinkle test: Spoon some hot jam onto a chilled plate and see if it wrinkles ahead of your finger when pushed through the jam.
• Flake test: Allow the jam to run off a spoon with the bowl held vertically. When a flake of jam remains attached to the lip of the spoon, it has reached the setting point.
  

After reaching setting point

• Once the jam has reached the setting point, turn off the heat and allow it to cool for about 10 minutes. This allows the jam to thicken slightly, so that the fruit pieces don't all float to the top in the jars.
  
• Pour the jam into the hot jars and seal the lids. Allow to cool completely. Label and enjoy! Store in a cool, dry place.