In a large sauce pan, combine the raspberries, lemon juice, and sugar.

Bring to a boil until the sugar dissolves and then continue boiling, stirring frequently, until the mixture thickens and you reach the gel stage.

Prepare your canning supplies. Bring the temperature of the glass jars up by processing them in hot water for several minutes, and heat a few cups of water in a small saucepan for the lids.

If the gel stage has been reached, skim off any foam and ladle the hot jam into the hot jars, leaving 1/4″ headspace.

Place the lids and bands on top, screwing on the bands just until fingertip-tight.

Place the full jars back into the boiling water and process 10 minutes.

Remove from the water and place the jars on a towel.

Let the jars cool. The seals should suck down (you’ll hear a popping noise as they do).