Woah! Vivid metallic purple on an indigo base, and guaranteed to draw attention, Sinful Colors Let's Talk is one extreme polish.
It's also very cheap (£2.99 from my local discount/import cosmetics shop), and wears well at about 4-5 days before first chipping. It applies wonderfully, as so many blue-based colours seem to. It glides onto the nail in dense, smooth layers without a hint of dragging.
The pictures have drawn out the blue and toned down the purple. In reality, this is really quite purpley. In the right light, it's similar in colour to the foil on a bar of Dairy Milk.
It's a gorgeous polish, all in all, and has drawn compliments several times when I've worn it.
There is a Sinful Colors UK website, but it looks kind of... primitive. I haven't used it, but they do have this colour in stock.