Step one: To bezel-set a cabochon, simply push the upper edge of the bezel around the gemstone. First, make sure your stone fits snugly in the setting by putting it in the bezel setting. View it from the side to make certain it sits level in the bezel cup. Next, begin pushing the bezel edge in around the stone using a bezel roller. Push one side gently against the stone, then push on the opposite side. Work completely around the bezel, alternating sides, until the whole edge of the bezel is crimped inward.
Step two: Now, use a burnishing tool (sold separately) to smooth the rough spots your bezel roller may have left. Draw the smooth end of the burnishing tool straight across the very top of the bezel with even pressure. Work around the bezel until the edge is completely smooth.