It's always best to look in Photoshop and set it up to see what's "out of gamut" before you send something off to the printer. I'm  not sure about newer versions of Photoshop, but the older versions had a command to show you which colors were going to be a problem. It "should" be under View/Gamut Warning...

Out of gamut are those colors which are outside of the cmyk system's capability to reproduce. If they are not corrected, they will turn dull or muddy when printed.

Laurie