The best way to tell you about it is to show you. First, take a look at the picture of a necklace from my shop. Amazingly enough, it sold quickly (yippee!), but I've listed another one in the shop using photos edited my new favorite way. Color pictures are absolutely the best way to go when listing your products. You want to give the customer an idea of the vibrancy and color of your products. Depending on your background, your item could get lost in the photo. It's kind of like those ads you see on TV where you can't figure out what they're selling. You think they're selling clothes, but it turns out to be perfume...
|Glass necklace on black mannequin|
If you don't have any photo editing software (or one you like), many people recommend GIMP. Not only does it have many of the advanced features that Photoshop users like, but it's FREE.
Reshooting all your photos to improve them may have to wait until you have more time, but this is a quick way to dramatically improve your photos in the meantime. If you do this to your product photos, please post a link - I'd love to see how it works for you.