Red gooseberries produce a deep-crimson jam, while green ones create a paler shade.
Place a few small plates in the freezer. Put gooseberries and 1/4 cup water into a medium saucepan. Cover, and cook over medium heat, stirring halfway through, until berries are just beginning to soften, about 10 minutes.
Stir in sugar, and mash berries against side of pan with the spoon. Cook, uncovered, stirring more frequently as jam thickens, until it is bubbling rapidly and the consistency of very loose jelly, about 30 minutes, skimming any foam that rises to surface. Remove from heat.
Perform a gel test: Remove a plate from freezer, and drop a spoonful of jam on it. Return to freezer for 1 to 2 minutes, then nudge edge of jam with a finger. If jam is ready, it should hold its shape. If jam is too thin and spreads out, return to a boil, testing every minute, until done.
Return jam to a boil before transferring to a jar. To seal and process, fill 3 hot, sterilized 4-ounce jars with hot jam, leaving 1/4 inch space in each jars neck. Wipe rims of jars with a clean, damp cloth; cover tightly with sterilized lids and screw tops. Transfer jars, using tongs or a jar clamp, to the rack of a large canning pot filled with hot water, being sure to keep jars upright at all times; cover with water by 2 inches. (Jars should be spaced 1 inch apart, and should not touch sides of pot.) Cover; bring to a boil. Process jars in gently boiling water for 5 minutes. Transfer to a wire rack; let cool 24 hours. Press down on each lid. If lid pops back, it is not sealed; refrigerate unsealed jars immediately, and use within 1 month.
Read more on how to sterilize jars. Sealed jars can be stored in a cool, dark place up to 1 year.