Thanks for your comments, everyone. I like the crispness of the photos and I do like the darker backgrounds. I've managed to add an additional Ott-lite to the front of my lightbox that brightens up the ambient light and item to be photographed. This definitely is making a difference in my test photos.
I don't think that the dark backgrounds are going to work for all of my stuff, though, as much as I'd like it to. It's really hard to get the right aperture and shutter speed for pictures on the really dark backgrounds - I'm finding that the background colours aren't staying true but are being washed out.
Michael's has a sale on most of their scrapbook paper so I bought a bunch today in different colours and patterns. The one we like the best so far looks sort of like sand. It's tan with some different shading in it and that's probably why it works for different colours. Plus the fact that natural colours or backgrounds tend to look good with a lot of things. It seems to work for some colours. The lightest-coloured earrings do need a darker background, though (they're still not popping off of the sand colour) so we'll go back tomorrow and see if I can find some darker browns.
Thanks again for all of your opinions on this: I really appreciate your help. When I have a few more test photos I'll put them up for you to see.
Oh - I've left the Jewelry on Etsy Team. I've been thinking of doing that for a while and since they left my name off the roster recently, this seemed like a good time to actually leave. Honestly, I've felt consistently ignored by the leaders and that the team wasn't doing much for me. Also, the organizer behaves badly in the etsy forums and has been muted at least twice from the forums for poor behaviour. Hopefully I'll find a team that is more suited to me.