Things have since gone from slightly troubling to considerably troubling. Somehow I miscalculated the amount of yarn I needed for the hat and mittens and was forced to go back to Windsor Button seeking another skein of the variegated yarn.
You probably know where this is going.
None of the yarn in that colorway was from the same dye lot, which would worry me more if it were a solid color, or if I'd be knitting the two different dye lots. But we're talking about mittens, two separate mittens. Plus the color is variegated, which surely disguises many evils. People, these dye lots are really different.
I resigned myself to ripping out the unmatching mitten I'm still working on, knitting it into a hat, then undoing my already-finished hat (in the old dye lot) and making it into a mitten that more closely matches the complete mitten. But then I started comparing each mitten to the hat.
Those are made from the same dye lot.
These are from different dye lots:
I realize the hat is folded different in the second picture and the garter stitch part DOES look a bit different than the cabled part, but honestly the hat seems equally the same/different as each mitten. It doesn't match either of them perfectly, nor does it look too jarringly different.
So I put the whole damn set together, because the purple of the cowl doesn't exactly go with any of it and I needed to see how bad this all is.
So, nothing quite matches each other, but also isn't jarringly different enough to cause strangers on the street to point and laugh. The whole thing matches better than my other completely-mismatched accessories, so I'll just stop overthinking it.
I think I'll cut my losses, finish the set, be grateful for the warmth, and plan better next time.