Prepare a boiling water bath canner and the necessary jars.

Combine the plums and apricots in a pot with 6 ounces of honey, the lemon juice, and the calcium water. Stir to combine and then let sit for a few minutes, until the honey has helped pull the juice out of the fruit.

Set the pot on the stove over high heat and bring the fruit to a boil. Once it is happily bubbling, reduce the heat to medium-high. Cook, stirring often, until the fruit has softened, the syrup has thickened, and the overall volume has reduced by at least a third. If your fruit is still really chunky, use a potato masher to help break down the big pieces.

Mash the pectin powder into the remaining honey and stir it into the cooking jam. Cook for an additional minute or two, until you see the jam visibly thickening.

Remove the pan from the heat. Funnel the jam into the prepared jars. Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 10 minutes.

When time is up, remove jars from canner and let them cool on a folded kitchen towel.

Once they're cool enough to handle, test the seals by pressed down on the lids. Sealed lids will feel firm and solid. Unsealed lids will pop up and down as you press them.

Sealed jars are shelf stable for up to a year. Unsealed jars should be refrigerated and used promptly.