How to Take Good Pics of Beaded Molecules?

Yesterday I went to IKEA searching for an adequate book shelf, and I was happened to find a nice light stand (I don't know the word... 燈座 in Chinese anyway). Together with a 23W light bulb that Jin gave me last time I was able to take some better pictures of our beaded molecules. I have picked out some of them that looks pretty well...











I found that, in particular, some of the color combinations of beads don't look so well while others, like the ones shown above, seem much more aesthetically pleasing when taken into pictures. And, interestingly, even if all the settings remain, the color of the photoed object actually affects the color of background in the pics, for example the last photo has some kind of bluish background. I guess using background cloth with opposite (or conjugated?) color against the object may produce better photo. Think I'll get some other cloths with different colors for further experiments...