Color systems like Pantone and CSI allow for accurate communication of color and easier production. In doing so, however, they essentially ‘short list’ millions of existing color representations (existing in print or on screen) into a limited set of a few thousand standards.  As a result, it may be that a search by RGB or CMYK or directly from an image will yield no close matches or ones that may not satisfy you.  

When working with a color matching system, compromise is a given. Therefore brands often work with the color companies to develop their own unique color standards.