Combine the fruit, sugar and cardamom in a large nonmetal bowl. Let stand at room temperature 1 hour, stirring occasionally. Or, cover and refrigerate overnight.
Place 2 small plates in the freezer
Transfer the fruit mixture to a large, deep, nonaluminum saucepan. Add the lemon juice. Bring to a boil over medium-high heat, stirring frequently until the sugar dissolves completely. Reduce the heat to medium and cook uncovered 25 minutes, stirring frequently.
Meanwhile, pour boiling water into the canning jars to heat.
Remove the pan from the heat, spoon 1 teaspoon jam onto one of the chilled plates and return to the freezer for 2 minutes. Nudge the jam gently with a finger; it is ready if it wrinkles. If it does not wrinkle, continue to cook the jam 5 minutes longer, remove from the heat and test again. When the jam tests done, remove the pan from the heat, and skim any foam from the surface. Drain and dry the jars and ladle the hot jam into the jars. Cover and let cool to room temperature. Store in the refrigerator.