PANTONE cmyk values in Illustrator do not match the PANTONE book, bridge, or website values

Hola,

En mi experiencia esa diferencia es debida a que los perfiles de color ICC usados en la PC no es el mismo que el utilizado para la impresion del libro (o pagina) de Pantone. De manera que al hacer la conversion, con cualquier intento colorimetricos produce valores diferentes.

Saludos

PANTONE has changed the CMYK values several times over the years as technology improved. The reason was that they could now create CMYK blends that more closely matched the ink colors. Rather than just adjust the existing solid color libraries to have the newer breakdowns somebody decided that they would leave the breakdowns for the solid colors as they were ten years ago and confuse the heck out of everybody. I've found that the best way to cope with this is to use the color bridge library (generally I use the coated one) when picking any spot colors. That way I can once again toggle back and forth from process to spot like I did in the thrilling days of yesteryear. Illustrator actually allows this easily as the toggle is readily available. InDesign makes it a little more difficult since the toggle is grayed out after you choose a color from the color bridge. However, if you then switch the color mode to CMYK then the toggle becomes active. I'm sure that there are some color purists out there who will say that all of this is blasphemy but I can honestly say that in my job in the production studio of a very large New York agency that our studio has never had a problem using this method.

I would create your own CMYK swatches and use the official Pantone equivalents.  I suspect your color settings and LAB values are affecting the CMYK conversions.  In the past, if you were to load a Pantone into your color swatches in Illustrator, then converted the spot color to CMYK ( a simple click on the CMYK icon ), the CMYK percentages would match the offiicial Pantone Solid-to-Process Guide.  Not sure what happened where now it does not work.