Here is Sinful Colors Casablanca:
earlier today, and I just took this picture so it seemed like a good time to talk about this polish. I bought this one day, a year or so ago, without thinking much about it, and it almost seems like it's so pale I'd hate it, but luckily I don't. I'm not sure why, given my normal dislike of pale colors on me. It's basically somewhere in the middle between gray and silver, so I don't know, maybe something about that combination makes it work for me. You could call it a satin silver, maybe? Note that there's what appears to be a line down the middle of the nail - I checked, and that's definitely a brush-stroke, but it's also not as noticeable as it appears to be in this picture. I definitely would try to minimize my brushstrokes when using this, for sure. (Not that that's always easy to do.)
(If you look at the "shade" part of this picture - like on the right side of the bottle - the gray actually doesn't look all that light of a color at all. I think that the base-color here is darker than you think, and that's probably why I like it ok on me.)
I haven't tracked down the original post (added: it's here), but I remember that the first time I wore it, I used thick coats and it was a very humid day (in fact I'm pretty sure it was raining) and I messed my nails up because it took them so long to set. I'm sure some of that was the humidity, that day, but still I'd say definitely try for thin coats.
Re availability: it doesn't look like it's current from Sinful Colors. It was available at a not-too-unreasonable price on Amazon, when I checked.