Stain or color concrete? Assuming either depending on the desired result. It looks like you stained the surround and colored the vanity, correct?
They were all done with integral color.
I played with acid staining for a little bit, but decided against it for my projects, although I do like the look that people can get out of it. Some acid staining is just ridic good. This is one of my personal favorites I've found online:

the very first one my old company did came out looking just like your surround, with that marbled variation look. It was fantastic. Customer hated it because it wasn't a solid consistent color(even though they were told it wouldn't be) and we covered the whole thing with $75k of terrazzo. The integral makes most sense though in case it gets chipped. Just surprised you could get that variation with integral color.(haven't worked with much colored concrete).
Buddy Rhodes, who is kind of a decorative concrete guru, developed a method that I used. Essentially, you make thick concrete, form it into balls, and press it into a mold. After it cures, you fill in the voids it leaves with a different color and polish. You can fill it until it's glass smooth, but I left some voids still there to for a slightly rustic look.
Here's an example of how it looks when completely filled in. Obviously any color combination can be used:
