The Calypso colorway is nice but not 100% rainbow.
It's not? What is missing? This is important. :)
I guess you will need to research the colors online and decide that for yourself. Researching yarn colors on Ravelry is my second favorite feature of the site after patterns of coarse. Because I buy most of my yarn online, I can get a better color idea off the different pictures and completed projects on Ravelry.
Also for those looking for specific yarns online, Google the specific yarn, not yarn shops. There are good online retailers who sell Berocco Comfort Sock yarn.
Oh...well, I mean, this is
me researching the colors online. ;-) You said that it wasn't 100% rainbow, so I figured you would be able to tell me what was not 100% rainbow about it. Different monitors display color differently, so viewing an image of something online is not always accurate with regard to color. (My hair, for instance, is purple, but it shows up blue on most people's monitors.)