blackberry seedless jam Recipe

2 qts ripe blackberries
1 box Sure-jel pectin
7 cups sugar

Wash and drain 2 qts ripe blackberries. Put berries through food strainer with a berry screen to remove all the seeds. Place 5 cups prepared berries in a large pot. Measure 7 cups sugar and set aside. Stir one box of pectin in the prepared fruit. Bring to a full boil, stirring constantly. Skim off foam and ladle into hot jars. Leave 1/4 inch headspace.Place on boiling water bath for 5 minutes.