Waterbath sealing a jar of jam that has 1.5" headspace left?

Gotcha! Thanks all. It was more than would fit in a tiny jar and then I'd just have the same problem was my first response. Then I got lazy (third batch in 2 days) and didn't feel like sterilizing a new tiny jar. Aah well. :) Guess I'll just have to eat it. SO good.

I agree, refrigerate and use first. To consider next time you're cooking up a batch of preserves: those teeny-tiny canning jars come in handy (I think they fit about a half-cup or less). I always wash 2-3 when I can jam to accommodate those awkward but precious last bits. They make a a nice hostess gift (with or without a basket of biscuits or scones). Cherry-cardamom jam sounds delicious!

Happens to me every time.

Stick it in the fridge and use it first. Too much air can lead to oxidization / discoloring and the jar might not seal properly with the extra space.