In a stockpot simmer plums and water until tender, about 30 minutes.

Line a strainer with a dish towel and place over a bowl. Place rhe plum mixture in the strainer, cover with the edges of the towel and let stand for 30 minutes or until the liquid measures 5 1/2 cups.

Return the liquid to the pot. Add the pectin, stir and bring to a boil.

Add the sugar and bring to a rolling boil for one minute, stirring constantly.

Remove from the heat. Skim off any foam.

Carefully ladle hot liquid into hot sanitized half-pint jars, leaving 1/4" headspace. Remove air bubbles. Wipe rims and adjust lids. Process for 5 minutes in boiling water.