Place saskatoons in a Dutch over. Add lemon juice. Heat gently until juice starts to flow. Simmer, covered, for 15 minutes. Add sugar, mixing well. Over high heat, bring mixture to a full rolling boil, stirring constantly. Boil hard for 1 minute. Remove from heat and immediately stir in Certo. Stir and skim foam for 5 minutes. Pour into hot, sterilized jars, leaving 1/4 inch (6 mm) headspace. Wipe jar rims thoroughly. Seal and process in a boiling water bath for 10 minutes.
Yield: About 9 cups (2.25 L).