Four blood oranges and one lemon became this fabulous concoction:
I think this was the right ratio of orange : lemon to get a marmalade that set up nicely without needing to supplement with extra pectin. The blood oranges were relatively thin-skinned and totally seedless, so I was a bit concerned. But I needn't have been.
The flavour is nicer than I anticipated in my wildest dreams—it smells tart (lemony!), tastes faintly bitter at the beginning (pithy!) and then a little sweet and floral (moro-y!), and you can taste the cardamom at the very end (spicy!), like a little sensual odyssey that repeats in every mouthful. (I am not sorry if this is a weird metaphor.)
The colour was a lot of fun to watch. After the chopped fruit had sat around in the fridge for a few days, it looked like this:
Boiling with sugar made it deepen to a darker and less-pink coral. But it's still decidedly less orange than the Seville orange marmalade from the other week.
In conclusion, I am glad I have a whole litre of it and I am not intending to share and next year I will make more of the exact same thing.