Wash and remove grapes from the stem
Place grapes in a medium stock pot, pour enough cold water to cover the grapes
Bring to a boil over medium high heat, reduce heat after the boil is reached and let simmer for 30 minutes
Using a potato masher or wooden spoon, smash and pop the grapes, strain through a fine sieve. (another method would be to use an immersion blender to achieve the consistency of jam).
Measure liquid, add enough water to equal 6 cups, return liquid to stock pot
Bring back to a boil, reduce heat to medium
Add 2 cups sugar, and lemon juice. Taste for sweetness, add more sugar if necessary
Stir until sugar is liquified
Bring back to a boil (this won't take long so keep an eye on the pot)
Add liquid pectin and boil for 1 minute, remove from heat. For thicker jelly, boil additional 2 minutes.
Place hot liquid in sterilized jars and process in a hot water bath for 5 minutes.
Grape jelly can also be kept in the refrigerator, in an airtight container for up to 3 months