Try taking the picture at 12:00 (noon) and hold a white piece of paper up for a shadow on the picture. This should give some more contrast to the beads. Also take some pics with out the paper too for more shadow. I use both and I usually get some great pictures out of one of these methods.
Look at my clear druks on my website. I took them at noon without the paper. Then I cut out the beads with the shadow and put a pure white back ground on them. Let me know what you think. You can then always play with the contrast too.
Hubby is somewhat disgusted with me, lol..... His clear lentils from last night will not photograph for beans! (lentils?) Personally, I find invisible lentils very humorous....
Thanks for looking! Carolyn