Attached Link: http://www.renderosity.com/mod/forumpro/media/folder_8/file_395440.jpg

The shot from thundering is a fine one..that will work but I believe should be in color.  The link is from one I put on a going thread here, taken with down and dirty methods at work.  I shoot quick pics to send email to customers, etc. These are not catalog quality by any means.

The light tent is a plastic tea pitcher, the translucent white sort with a hole cut in the bottom for the lens. I sanded the inside a bit to give better diffusion. Still, with added light the stones will show and sparkle and there will be reflection off the metal.  Light for this one was a desktop flourescent lamp. Go figure! Down and dirty and quick.

Added thought on photos for auction sites(i.e. eBay):  The local places that offer the service offer FULL service. That means they not only photograph but list and sell and take a percent of the sale price, if it sells. That is a lot to do, including perhaps the mailorder part.  The business becomes much more than the photo and may be more than you want.

As for the camera choice, I have a Nikon D70 and a D200.  I would go with the D200 for certain.  The camera is a fine one and will do what you need.

Sorry, digressed a bit from your quest into auction site photos...I happen to see that as more than the photo part for the general consumer. Is that what you want?         TomDart.