Wash and stem the grapes.
In a large stainless steel saucepan, combine grapes and 2 cups of water.
Bring to a boil over medium-high heat, stirring frequently.
Reduce heat to low and use a potato masher to crush the grapes. Continue cooking for 2-3 minutes.
Line a sieve or strainer with a couple of layers of dampened cheesecloth, set over a deep bowl.
Pour the grape mixture into the cheesecloth-lined strainer and allow it to sit for about 2 hours for the juice to extract.
You should end up with four cups of clear grape juice. If you don't get the required four cups, add a half cup of boiling water to your strainer.
In a large, deep stainless steel saucepan, combine grape juice and sugar.
Over high heat, stirring constantly, bring to a full rolling boil.
Stir in pectin. Boil hard for one minute. Remove from heat and skim off any foam.
Quickly pour jelly into sterilized jars, wiping the rims with a damp paper towel. Center lids on jars and secure rims to finger tight.
Place jars in a boiling water canner for ten minutes.
Remove jars, allow to cool, ensuring they are sealed, and store.