This pattern uses just one crochet stitch - Treble Crochet (this is called a Double Crochet in the US). It's an incredibly simple but very effective mixed stripe using two rows of crochet for each colour. The simplicity of it...
Granny Square Pattern - A free crochet pattern
Modern Baby Blanket, Granny Square Baby Blanket, Teal and Gray Baby Blanket, Turquise Baby Blanket. $50.00, via Etsy.
Rickrack Rainbow Baby Blanket By Red Heart Design Team - Free Crochet Pattern - (ravelry)