Instructions

Bring grapes and water to boil in Dutch oven over high heat. Reduce heat to medium, cover, and simmer, crushing grapes occasionally with potato masher, until grapes are soft and separated from their skins, 5 to 10 minutes.
Working in batches, strain mixture through fine-mesh strainer into large bowl, pressing firmly on solids to extract as much liquid as possible; discard solids. Clean strainer, line with triple layer of cheesecloth, and strain juice again into large measuring cup. Let juice cool, then cover and refrigerate for 24 to 48 hours. Before making jelly, strain juice again through cheesecloth-lined strainer and measure out 3½ cups; reserve any extra juice for another use.
Set canning rack in large pot, place four 1-cup jars in rack, and add water to cover by 1 inch. Bring to simmer over medium heat, then turn off heat and cover to keep hot.
Combine ¼ cup sugar and Sure-Jell in bowl. Bring juice to boil over high heat. Whisk in Sure-Jell mixture and bring to boil. Whisk in remaining 2¼ cups sugar and bring to vigorous boil. Once boiling, cook for 1 minute, whisking constantly. Remove pot from heat and skim any foam from surface of jelly using large spoon.
Place dish towel flat on counter. Using jar lifter, remove jars from pot, draining water back into pot. Place jars upside down on towel and let dry for 1 minute. Using funnel and ladle, portion hot jelly into hot jars, leaving ¼ inch headspace. Slide wooden skewer along inside edge of jar and drag upward to remove air bubbles.
For short-term storage: Let jelly cool to room temperature, cover, and refrigerate until jelly is set, 12 to 24 hours. (Jelly can be refrigerated for up to 3 months.)For long-term storage: While jars are hot, wipe rims clean, add lids, and screw on rings until fingertip-tight; do not overtighten. Return pot of water with canning rack to boil. Lower jars into water, cover, bring water back to boil, then start timer. Cooking time will depend on your altitude: Boil 10 minutes for up to 1,000 feet, 15 minutes for 1,001 to 3,000 feet, 20 minutes for 3,001 to 6,000 feet, or 25 minutes for 6,001 to 8,000 feet. Turn off heat and let jars sit in pot for 5 minutes. Remove jars from pot and let cool for 24 hours. Remove rings, check seals, and clean rims. (Sealed jars can be stored for up to 1 year.)