Rainier cherry jam captures the unique flavor of rainier cherries. It tastes more like apricot jam or citrus marmalade than cherry and is a one-of-a-kind-treat.
Wash, pit and halve the cherries. Add them to a saucepan with the lemon juice and bring them to a boil.
Cook the cherries for a few minutes until they release their juices, and then mash gently with a potato masher.
Add the calcium water into the boiling cherries.
Add the powdered Pomona's pectin into the sugar and stir to completely incorporate. This step is important because it prevents the pectin from clumping when it hits the hot fruit.
Add the sugar and pectin mixture into the boiling fruit and stir to completely incorporate. Cook for an additional 1-2 minutes until the mixture begins to gel.
Ladle the jam into prepared canning jars, leaving 1/4 inch headspace. Process for 10 minutes in a water bath canner, or store in the refrigerator.
This recipe makes 1 pint of jam or two half-pint jam jars. It can safely be tripled, to make up to half-pint jars at once.