The example of my nw0 friend with grey hair I posted earlier would match your experience. He has black hair (well, greying but still) but his beard looks like it's rusty, far from black. Isn't it copper deficiency basically?ive noticed the same with early greying and good hair.
Im interested in your thought process gorillahead, I have massive shedding, a the same time the color is turning from black to light brown, and the majority of my beard has also lost its color from black to ginger.
Sounds like it could be a zinc/nutrient problem but have tried to correct all.