You can sew the Margarita beads into clothing, or you can glue them onto a card like we did in this free design:

http://www.artbeads.com/glitter-flowers-get-well-soon-card.html

You can also use them to make little magnets like we did here with the crystal flatbacks:

http://www.artbeads.com/swarovski-rhinestone-magnets.html

You can use them on leather, however I have found that a sueded leather works the best. I encrusted the suede leather on some birkenstocks with great success. The hotfix was the easiest to do and had the best final appearance. If it is a smooth leather, you may ned to rough up the surface to give the glue something to adhere to. You should always do a test spot in an inconspicuous place to determine if the crystals will hold.

Absolutely not. The backing on the Swarovski Flatback Rhinestones can sometimes come from the factory with slight imperfections. We tested many of the stones and found that there is no difference in the look of the finished items. The glue will not show through when applied properly.

I would try wiping them gently with a buffer cloth.