Hi.  This guide is focusing on color in eBay photographs, particularly colors of said photographs, and how they are displayed on monitors.

It is good to keep in mind, that there are many factors influencing the color of a photograph.

The first thing is lighting.  Pictures shot under natural light tend to bring out a truer version of the color of an item.  Pictures shot indoors are effected by the percentage of natural light in a room, as well as the artificial light.  Different lights will produce different results.  I'm not 100% positive on the differences created by using over halogen, or whatever light source your using, but these are still good things to keep in mind.  Also note that with too much light (which happens outdoors sometimes) you can get a burnt picture, and the color won't even be close!

The next thing is the camera.  Each camera is a little different, even the same brand of camera may be different from another from the same manufacturer, even the same model.  The differences may not be HUGE, but there is still a difference.

Then comes in the Video card factor.  Video cards are tweakable so you can have different values for your colors (Red Green Blue, or RGB), gama, contrast, etc.  The problem here is everyone's video card is set up a little different.

Then comes the monitor, which is the final link in the color chain.  Your monitor, much like your video card, has its own setup options.  On my work station, I have 2 video cards, and 2 monitors.  Each setup is identical, but there is dramatic differences between the two screens.

Now, each of these components makes a small difference on its own, but can make a dramatic difference when they are all combined.  This said, here is some advice that may be useful for eBayers:

Buyers:

If the color of your item is VERY important to you, ask your seller what light conditions it was shot under, and if you can get a picture taken in natural light.  Keep in mind though, that with all the factors effecting color in pictures, that there will be slight variations from the real thing.  Also, ask if the color appears correct on their monitor, if they get a pretty close match, your at least eliminating some factors (bad lighting, poor camera, poor image compression etc.)

Sellers:

It may be a good idea to shoot under natural light, take your item outdoors and shoot it against a nice background.  Compare each of your digital images to the real item, if it is very close, then you are on the right track.  If its a little off, maybe change your lighting, or camera settings, and try again.  Keep in mind that you can't control your customer's color settings, so there is little that can be done that way, but getting a close match on your end will mean that your customer is getting a better depiction of your item, and you'll be saving yourself some problems down the road.  Keep your camera/scanner clean, wipe the dust off before every big eBay session.  Try and keep your lighting consistent, or even add something in the picture to contrast (something that everyone know the color of, a coke can, or simpsons figure, whatever), It may make your picture look a little tacky, but take another without your contract item, and make that one your first image.

Remember, we're all in this together!

I hope this sheds some light on this colorful situation.