The Kraft recipe for persimmon jam calls for 6 ripe persimmons, 1/2 cup of lemon juice, 1 box of pectin, 1/4 teaspoon of butter and 6 cups of sugar. It is best to sanitize any jam jars and rubber lid sealing rings with hot water before making the persimmon jam.
Remove the stems from the persimmons and scoop out the pulp. Discard the skins of the fruit, as they cannot be used in the jam. Pour the pulp, 1 cup of water and the lemon juice into a saucepan over medium heat.
Add the pectin and butter to the ingredients in the saucepan, then increase the heat so that the fruit mixture boils. The mixture's temperature should be such that it continues to boil even while it is being stirred.
Add the sugar to the saucepan, and boil the ingredients for an additional 4 minutes while stirring constantly. Reduce the heat and skim any foam off the top of the fruit mixture with a spoon. Pour the mixture into the jam jars, leaving about a 1/4 inch of space at the top, and tightly seal them.
Transfer the jars to a pot of water. The water level should be 1 or 2 inches higher than the top of the jar. Boil the water for 10 minutes. Remove the jars and refrigerate them.