not to run beat this thread to a pulp, but CA addressed this in April '99
Q: Some cigars have bright white ashes, others are almost a charcoal gray. What determines the color of a cigar's ash?
A: The magnesium content of the tobacco. High magnesium yields a white--and flaky--ash, low magnesium a grayer one. As for taste, it's generally considered
more desirable to have high magnesium, and thus a white ash, but that's by no means a firm rule. Some of Cuba's great cigars often have very dark gray ashes.
Thanks for posting, I learned something new. And your right, my tongue is whiter. Thanks!