Slate

This is RGB Slate:

This is the only RGB polish I have, and apparently it's discontinued. (There's a pretty similar shade, Gunmetal, on their sale page, currently.) Vampy Varnish says that RGB started out with ten colors and Slate is one of the original ten. I wore this recently under Butter London Knackered, and I think I've maybe worn it one other time. It's pretty but it's the kind of thing I tend to skip over in favor of something showier. I really should get over that.