Black Knight needs little introduction, it's a black base with multi color glitter, and I'm sure you've seen swatches of it before. It's such a great polish - a lot of brands attempt the "multi color glitter in black base" thing, but butter LONDON is the only one I've seen so far that did it right. Application is as smooth as, well, butter, and the glitter is packed densely enough so that it's not covered up by the black base. Only two coats are needed for full coverage.
Since it's so glitter heavy, Black Knight dries super fast. The finish is gritty, but a thick coat of your favorite top coat will take care of that easily.
I'm in love - I've already worn Black Knight twice since I got it, and I have a feeling it's going to be my go-to black polish for a looong time.
Here's two coats of butter LONDON's Black Knight over Orly Bonder, topped with Seche Vite: