Good hash in my experience derives it's color from the trichome heads. Which can be a reddish, good oils will often be an orange to red as well.

I've grown strains that were made up of bright purple and red flowers with leaves that changed from green to pink in flower. All kinds of colors are possible, but green is the most prominent, and what the title of your post was specifically talking about so that's what I am focused on.

herb that starts green doesn't become totally brown with a "good cure"...the only way something goes from all green to all brown is through bacteria.