Cobalt or Klein

I got inspired over December 2012's InStyle magazine "Color Crash Course" silver. I dug out my grey trousers and paired them with my blue button down shirt. I am a bit confused now as I don't know how to refer to this blue shirt, is it cobalt ? blue klein ? A.Byer grey trousers - Forever 21 blue button down shirt - Me Too burgundy loafer heels - Silver belt Forever 21 Or is it just blue ?