Apparently I'm in the groove because I have a couple of dark blue coats, one Cos one from the Jean Muir closing down sale, which I wear with LBDs and black patent shoes
Here's Jess on how to put it together:
Wearing blue and black together takes a bit of getting used to. It's a combination that is neither all-out moody, like black and grey, nor straight-up chipper, like blue with white, but betwixt and between, like a shadow on a sunny day. Handy for days that are neither red-letter, nor a washout, but somewhere in the middle.
However, done badly, black and blue looks like a cheap-trying-to-be-cheerful school or checkout uniform. Be aware of this pitfall in daywear - a boxy navy blazer and straight black skirt, for instance, are to be avoided. To give this particular danger a wide berth, you need to add to the mix something out of the workaday: a slinky fabric, a spot of sharp tailoring, foxy shoes, whatever. It is tempting to opt for baby blue rather than bright blue with black, because it seems like a softer combination, but that looks like business wear. There's nothing wrong with that, but it's not fashion, darling.