Pick through your blueberries carefully, remove the stems and rinse your berries with clean water.  

Place the blueberries and lemon juice into a medium saucepan.

Over low heat, slowly cook the blueberries until they begin to pop and produce their own juices.  Stir and carefully watch to prevent scorching, especially at this early stage.

Lightly mash the blueberries as you stir and cook them, allowing them to break apart.

Once the blueberries and lemon juice have created a significant amount of juice, add the sugar, stirring to dissolve.

Turn the heat up to medium-high, and continue to stir and check to make sure the jam is not scorching.

Cook the jam until it has reached the gel stage, which should be approximately 20 minutes or a little longer.

Test the jam to see if it has reached the gel stage by using the cold plate test, or until the temperature reaches the gel stage at 220° F.

Ladle or pour the jam into prepared jars or containers.

Preserve the jam by using a hot water bath canning method, or after the jam has cooled, keep the jam refrigerated or frozen until ready to eat.  If canning, process in a water bath canner for 10 minutes (15 minutes if above 6,000 feet in elevation).