These earrings were really simple to make. I collected several little rocks (so I could play around with them and see which ones I liked together) and then just to be on the safe side I boiled them for 5 or 10 minutes.
Once they were clean and dry I grabbed a couple scrap pieces of foam core to hold my earring backs in place. A drop of Bead Fix (or probably any superglue would work) on each post then I put my rocks and place and let the glue dry. You just set them on the glue - no need to press and hold them in place.
I also made a pair in gold! The only thing I did differently for these was to use a Krylon Gold Leaf Pen on the rocks before glueing them to the earring backs.