This, among other reasons is why every company needs graphic standards.  And, the rational for requesting a printed sample.  I’m not an artist or a printer, but I’ve sure learned from my mistakes.  Here’s a few things I wished I had known 10 years ago. Graphic standards define how your logo, name, and brand may be used.  They define color combinations, placement, and essentially protect your identity from being diluted.  One of the many components of graphic standards is color.  They’ll almost always list the PMS numbers and sometimes the CMYK and RGB combinations.  This takes the guesswork out of colorization for vendors because these are standard combinations.  They know how to do PMS 208 rather than just trying to match a sample (although I think providing a sample is always a good idea). Now, once you have the PMS number, is it going to be perfect?  Maybe.  Maybe not.  But it’s a great starting place.  It does get more complicated. Depends if it’s coated/uncoated, how much the paper absorbs, etc.  This is where I believe  a sample becomes important – both a sample of what you are trying to match and a printed sample of the end product.  Having a sample printed may cost you, but if it’s important that the project be perfect, it’s worth the expense.  This is easier with a collateral piece than say a mug.  Get a printed sample when you can…you won’t regret it.  And, if you can’t, provide them a sample of what you are trying to match and cross your fingers. One other pearl of wisdom, find good artists, printers, vendors that you trust and they’ll help walk you through the process.  If they don’t want to take the time to help you find that perfect color or figure out why your maroon logo is turning out pink, move on.  Someone else will!