In a heavy saucepan over medium-high heat, combine blueberries, 1/2 cup water and lemon juice. Bring to a boil, then reduce heat and simmer gently for about 8 minutes, stirring frequently.
Meanwhile, soak gelatin in 1/4 cup cold water.
Remove blueberries from heat and stir in gelatin and sugar.
Pour into hot, sterilized jars and seal. Cool and store in the refrigerator.
