I just found something really amazing on SOR! I am not a cover collector as such but I always keep my eyes peeled for covers or stamps with coloured cancels. I have a few reds, a few blues and now my second green! The really rare colours are orange and yellow, yellow cancels can bring a bonus in Scott's US specialized in the thousands. One of my greens is on #114 and has a bonus of $400, I picked that up here as well!! This one carries a $200 bonus since there are two stamps. I know CV's mean very little, except making the collector feel a bit better, but this is a wonderful cover and I thank the seller very much!! Check this out, a real treasure!! How about using this post to show some of your coloured cancels?

EDIT: My bad, I just heard from the seller and he said it is blue which looks green on a yellowish cover. Not as good as $1 instead of $100 but I still really like the cover!! It just illustrates how hard it can be to interpret colours! I do still have one really nice green cancel so "what the heck", It's still a fantastic looking cover and I'll enjoy it!
EDIT#2: I was looking through my US book and noticed that my other "green" cancel was on a yellow cover. It sure as heck looks green to me!! Does all blue on yellow look green? Hopefully not!!!