What does ash tones do to hair colors?

Ash tones means that the color is cool. For example, Kate Hudson' and Lauren Conrad's hair is golden-blonde which is warmer, more gold and less ashy than Nicole Richy's. While Kate Winslet's hair is warmer than all of the above because it has redder tones in it. Often toners are used to make hair colors more ashy and thus cooler and less brassy or warm.