1kg blueberries, washed (I'm lazy and used half fresh and half frozen)
1kg jam sugar (I used CSR Jam Sugar)
1/2 cup lemon juice
Sterilise your jam jars and lids by placing on a tray in a 180˚C oven for 10-20mins.
Add all ingredients to a large pot and stir on a low heat until sugar has melted.
Turn heat up to medium-high and allow to boil for 10-15mins.
Do the crinkle test by pouring a spoonful onto a saucer and placing in fridge or freezer until cooled and then touching with your fingers. If it crinkles then the jam is set, if it is still liquid then allow jam to boil again for another 10 minutes.
Take jam off the heat and allow to cool slightly before dispensing into sterilised jars.
Wait for jam to be cool down to warm before sealing.