This is the most beautiful royal indigo blue. Whenever I have it on I cannot stop staring at it -- and not just me. I catch people gazing at them when I type, get my coffee or play with my phone. I put this on (read: got a manicure) two days ago and at least three people have complimented me on it. If there is a blue you NEED, it is this one. Maybe except Chanel Blue Satin, but that's a whole different ball game.
Caveat: It gets ridiculously thick, but that's true for all metallics. My bottle literally won't move anymore, so I only get this in salons.