Here's a bit of advice to help avoid color variations. I don't recommend manipulating the photos as there are too many variables (monitors, video cards, etc.). Rather, try to find the right light and background to produce color as close as possible to what you see. I would avoid white or very dark backgrounds. Most of us use cameras that average all that is in the viewfinder to determine the proper exposure. The background can move the average to where the exposure is not correct for the cue, thus making it look darker or brighter than it should be. Sometimes poor exposure, among other things, can impact the color balance in some digital cameras, too.
Anyway, I'm glad this is getting resolved. I would advocate posting a disclaimer about color. Many businesses do that. A good example is picture framing supply companies........
Karl