one thing that i have been taught over the years is not to look at the "Color" so much... but look at the arch running to the electrode... optimal is when your burn marks are right on the curve... if the burn mark is toward the thread or on the bottom of the curve as i like to call it your running lean... if it is above or over the electrode it is running rich
(don't know about champion but it's 99% right on NGK's)
made this image real quick for reference