By Tessie2


4 cups grape juice (about 3 1/2 pounds Concord grapes and 1/2 cup water)
3 cups sugar
To prepare juice: Select 1/4th firm-ripe and 3/4th fully-ripe grapes. Wash and stem grapes. Crush grapes. Add water; cover; bring to a boil over high heat. Reduce heat; simmer 10 minutes. Strain juice through damp jelly bag or several layers cheesecloth. To prevent formation of tartrate crystals in jelly, let juice stand in a cool place 12 to 24 hours; strain again to remove crystals.
To prepare jelly: Put grape juice in a large saucepot. Add sugar, stirring until dissolved. Boil over high heat, stirring constantly, to 8 degrees F above the boiling point of water or until jelly mixture sheets from a spoon. Remove from heat. Skim foam if necessary. ladle hot jelly into hot, sterilized jars,leaving 1/4th inch headspace. Adjust two-piece caps. Process 5 minutes in a boiling water canner.
Yield: about 4 half-pints.