Place sugar in an ovenproof shallow pan and warm in a 250°F (120°C) oven for 15 minutes. (Warm sugar dissolves better.)
Place berries in a large stainless steel or enamel saucepan. Bring to a full boil over high heat, mashing berries with a potato masher as they heat. Boil hard for 1 minute, stirring constantly.
Add warm sugar, return to a boil, and boil until mixture will form a gel (see tips, below), about 5 minutes.
Ladle into sterilized jars and process as directed for Shorter Time Processing Procedure .