Terrible thing. Pretty color. Why did envy turn green? American paper currency is sort of green, but is that where it originated? That wouldnt really make any sense either. Well, I turned copper with envy when I saw how many pennies she had. That doesnt work very well at all.
Green is often related to evil. The Wicked Witch of the West was green (neither her color or wickedness are ere reasoned). Slytherin's colors are green and (white is it? or silver...). It is in costume theory related to envy, greed, and evil, but green is a color of plant life and renewal. Energy, rebirth, youth are embodied by that color too. The original point you may remember being why is envy green?
When I am envious I dont feel particularly green. I would almost say purple, but I dont think that gives purple any justice either. Black already has enough ill thoughts assinged to it. I suppose the best thing to say about envy is it makes me feel bruised. (not in a good 'hey look i have a bruise' way either). I want something, and at the same time I want to not want it. On top of that I'm working on convincing myself that I have just compensation. Mixxed within is a frantic assesment of my chances of aquiring this that is envied. Feeling bad for envy and then trying to decide if I really want this thing for myself. So I usually avoid it as I can.