It's from their Studio line, and cost £3.50. It's not immediately obvious that it's blue rather than black, as it is a very deep navy, but once applied, it's a little more subtle than black and compliments grey and other blue shadows really nicely.
This is how it looks on the skin. It's not hugely pigemented, but you can easily go over the line twice to deepen the colour. It dries quickly, and will stay put all day as long as you don't rub it at all. I like it, and apply it with the ELF Small Angled Brush, also £3.50.