Yield: 4 x quarter-litre (1/2 US pint / 8 oz) jars.
Put on burner to start coming to a boil. If using sugar or Splenda, add the lemon juice now (otherwise, don't add it yet.)
When blueberries have come to a full boil, stir in the pectin mixture a dollop at a time. If using a liquid sweetener such as honey or liquid stevia, add that to the pot now too.