Cabochons come in many shapes and are made from a variety of stones such as hematite, aventurine, and agate. Though there are many ways to wrap cabs with wire, I find this method works well for me. If you've never tried to wrap a cab before, I recommend that you start with a fairly large cab. The larger the cab, the easier it is to handle. Of course, the larger the cab, the more wire you’ll need. Here are the supplies and equipment you will need:
Your choice of size and type of cabochon
About 1-foot of 24-gauge half-round gold-filled wire
*22-gauge dead-soft square gold-filled wire or 20-gauge dead-soft square gold-filled wire
**Clamps
Wire pin vise
Masking tape
Marker
Polishing cloth
Ruler
Wire cutters
Chain-nosed pliers
Round-nosed pliers
*Some people recommend using 20-gauge vs. 22-gauge square wire. However, 20-gauge is much stronger and harder. So, if you’ve got whimpy hands (like me) then try using 22-gauge.
**For clamps, you can also use those black binder clips available at office supply stores which are used for binding papers together. Just make sure you cover the inside of the binder clips with a soft cloth or something so you don't scratch up your wire.


From: http://jewelrymaking.about.com/od/pendantswrappedcabs/ss/wire-wrap-cabochon.htm