This full-color palette can be opened in Photoshop and used as a source for sampling colors with the eyedropper tool. Shrink it for convenient desktop storage, and then zoom in to enlarge a particular part of the spectrum. You can also open the file in a second window (Window, New Window) and choose View, CMYK Preview to see by comparison what will happen to the color gamut when a file is converted from one color system to the other using the settings specified in your Separation Setup dialog box, accessed through File, Color Settings.    