From Can I dye my beard or hair black?, we see that there's a bunch of ahadith which prohibit dying one's hair black. For example:
"Some people will dye their hair black like the breasts of pigeons at the end of time, but they will not even smell the fragrance of Paradise."
Sunan an-Nasa'i 5075 [grade: sahih]
However, many people have naturally occurring black hair, which raises the question:
Question: How do we reconcile ahadith which imply dying one's hair black is haram, given that black hair occurs naturally?
Logically, we can infer there are two requirements to this problem:
the color black, since dying one's hair other colors was not considered a problem, and
the act of dying (not simply possessing black hair), since non-dyed black hair is fine.
Other questions on this topic are