4 cups blueberries
2 cups sugar
2 tablespoons lemon juice
1 tablespoon lemon zest
1 packet pectin, optional
Wash blueberries
Mash blueberries slightly
Combine blueberries, sugar, and lemon juice in a pot
Add pectin if using
Bring to a boil over medium-high heat
Stir constantly
Boil until thickened, about 10 to 20 minutes
Test for set on a chilled plate
Remove from heat
Skim off foam
Pour into sterilized jars
Seal jars
Cool completely
Refrigerate or process for storage