Combine blueberries, lemon juice and water in a medium sauce pan and set the heat to high. Crush the blueberries with the back of a spoon. When the mixture begins to boil stir in the mint and sugar. Allow the mixture to boil for 10 to 15 minutes until the consistency thickens. Allow the jam to cool slightly before transferring into four 8-ounce Mason jars and refrigerate.