Thanks to an inquisitive community member, she also spilled the beans on how to do the same with stone fruit.
So once berry season is over, no need to be sad: Stone fruit jam time is here. According to Mrs. Wheelbarrow, you can make refrigerator jam with any stone fruit if you follow her berry jam instructions, but once you get to step three (making the fruit mixture)...
Use 3 pounds of stone fruit, pitted and peeled, and 3 cups of sugar. The key to stone fruit jam is the chop it into small, uniform pieces. Any stone fruits (peaches, apricots, plums, nectarines, pluots, cherries) will work.
Because all types of stone fruit have different pectin levels, though, your jam will set a little differently. If a firmer jam is desired, next time, add either one green apple, grated, including the peel, or one underripe kiwi fruit, diced, when the fruit is added to the syrup. Either option will reliably strengthen the gel.
Continue with her instructions and there you’ll have it: Stone fruit jam, the willy-nilly way. Now for what to do with that excellent jam?
Tell us: What kind of jam are you making this season!