Marcellus, who is all black, had all black whiskers when he was little with the exception of one white whisker on each side. We thought that so cute. Well, he eventually lost those white whiskers, not sure if they fall out and get replaced or just grow, I assume they get replaced. Anyway, no white whiskers now, all are black.
Willow's whiskers are multicolored, just like her fur. Several are two or three colors on the same whisker! Spot's are all white. My boyfriend's folks have a solid gray cat and a solid black cat, and both have whiskers that match their fur. My mom's cat used to have mostly black whiskers, but as she has gotten older, a lot of them have turned white.