Recipe yields 5 half-pint jars.

PREPARE FOR CANNING

• Prepare the calcium water: Combine ½ teaspoon calcium powder (from the small packet in the box of Pomona’s pectin) with ½ cup water in a small jar. Screw on a lit and shake until well-combined. You'll have more than you need for this recipe. Store the excess in the refrigerator for use in making additional jam or jelly recipes.
• Wash the jars you'll use, making sure each is clean and free of nicks in the rim, which could impede sealing.
• Wash the lids and rings in hot soapy water. (If you're using non-Ball brand lids, prepare as suggested by manufacturer.)
• Place empty jars in a canning pot or large stock pot with enough water to cover by an inch or two, cover pot, and set on high heat. It can take awhile for the water to heat, so get it started before you begin making the recipe.

MAKE THE CHERRY JAM

• Measure the diced cherries, lemon juice, lemon zest, and calcium water into a large saucepan; bring to a boil.
  4 cups cherries, 1/2 cup lemon juice bottled, 1 - 2 lemons , 3 teaspoons calcium water
• Meanwhile, combine the sugar with the pectin until it's thoroughly combined.
  1 cup sugar, 3 teaspoons pectin
• When the cherry mixture comes to a boil, stir in the pectin and sweetener, stirring vigorously for 1 to 2 minutes to dissolve the pectin while bringing the jam back to a boil. Remove from heat when the jam boils.

CANNING THE JAM

• Remove the empty jars from the canner, draining the water back into the pot.
• Ladle hot jam into quarter-pint, half-pint, or pint sized jars, leaving 1/4" head space. A canning funnel makes this easy.
• Wipe jar rims to remove any jam that may have spilled. A clean rim is essential to a good seal.
• Set jar lids in place. Screw bands on finger tight.
• Use a jar lifter to gently submerge jars into hot water in the canning pot. Water should cover the top of the jars by an inch. The water will cool somewhat in reaction to the addition of the jars. Return the water to a simmer and then set the timer.
• Process for 10 minutes 0-1,000 feet altitude; add an additional minute for every additional 1,000 feet in elevation.
• Remove jars from water using the jar lifter and transfer to a solid, towel-covered surface. Allow to cool for 24 hours.
• Check seals. Lids should be solid and pulled down tight. (if they flex and pop, the jar didn’t seal; put unsealed jars in the refrigerator and use those first).
• Remove rings and wash outsides of jars. Store in a cool, dry place.