After having yet another conversation about this, I’m writing this exasperated post …
Just because your print lab accepts Adobe RGB files, doesn’t mean they can print the entire Adobe RGB gamut.
A lot of consumer labs expect sRGB files, and print poorly if you give them something else. But the good labs can accept files in any colour space at all – Adobe RGB, ProPhoto RGB, etc.
Does this mean they can print any colour in the world? Of course not. It just means that they have an excellent colour-management workflow in place, and will convert your images to their print space before printing.
If you provide them with colours that are too bright for print, they’ll be clipped, and won’t print properly. Logical, right? But a lot of people seem to think that if their lab accepts Adobe RGB files, then they must be able to print the whole gamut. Not so, I’m afraid.
But here’s the good news. If your lab is good enough to be able to accept any colour spaces, it stands to reason that they’re also good enough to provide soft-proofing profiles. Check your lab’s website for their print profiles, then soft-proof your images to see if any colours are at risk of clipping.
For more information, see my Soft-proofing tutorial