How do I know when I have a “gel”?

The great fear that all aspiring jam makers bring to the stovetop is: how will I know when I have a “gel”? Which is to say, how does one know when the point of maximum thickness has been reached? All sorts of home-spun methods have been devised to ascertain the doneness of jam. There’s the spoon-drop test, the cold plate test and the finger-in-the-jam-droplet viscosity test, none of which are truly definitive. Truth is, even the most experienced jam-makin’ granny is occasionally blind-sided by a jam that appears to have gelled, but which really hasn’t. That’s the way the cobbler crumbles, but there are a few rules of thumb that will tell you when you’ve given your jam its best chance for thickening. First, where berry jams are concerned, most gels happen within about 8 minutes of adding your lemon juice…sometimes in as little as two minutes. A berry jam will be overcooked after about 15 minutes. Most stone fruit jams take longer, up to 25 minutes for apricots, which will be well overcooked much beyond that. What happens when a jam overcooks? At first they simply go runny, but after that, well…I have a story about that…