I got my first zoas on friday! I will post pics soon... I bought them BRIGHT orange, but they are still brownish since putting them in my tank, and I hope they color back up!
It really depends on your light. If you are running more in the yellow spectrum, it will go more brownish (your 10K). The more blue you get with your lights (20K) the better color you will see. If they are stressed, they also lose color (usually when I fresh water dip them), but they color back up in a few weeks.
have fun with your new zoas!!!