What materials would you use to make a handle for a cooking utensil?

Micarta for basic knives, gemstone for high end knives. Micarta doesn't swell/contract with moisture or heat, and in inexpensive in most cases both of which makes it a better choice then woods, bones, etc.

Gemstone is considered by some to be the ultimate handle material. It does not change sizes, is moisture resistant, scratch resistant and will outlast the knife in most cases. The only drawback is its expense as gemstone is naturally more expensive and only very skilled knifemakers or lapiders can make them.