My sensei's dojo and all his student's affiliate dojo:
shodan and above: black
(no stripes at any rank)
hakama when begin to assistant instruct.
The kicker of this is that our organization allows it's individual dojo to adopt it's own policy on this. Some use white for all kyu ranks, some use white until nikyu then brown, then black for shodan. I believe that some dojo in our organization forego the hakama and some may require it from day one, still others require it from day one for women but not men (if I remember correctly, which is happening less and less these days
It makes working with people at camps interesting