If you'd like to make one of your own, here's the tutorial:
River Rock Business Card Holder
Flat, medium-sized river rock (about 1cm thick)
Drill press with appropriate bit
10 inches of copper wire
1. Drill a hole into your rock until you have almost reached the other side. Do NOT drill through to the other side.
2. Wrap one end of your copper wire around the chopstick. Continue wrapping, each circle larger than the one before, to create a spiral. Leave 3 inches at the other end.
3. Once you have created the spiral, press your fingers into the last few inches of the wire to shape them, as desired.
4. Using both hammers, flatten your wire along the bottom 3 inches and on the outside of the spiral.
5. Squirt a small amount of glue into the hole in the river rock.
6. Stick the end of your wire into the hole. Hold it upright until the glue dries.