Use these burs to cut a seat for faceted stones in bone dry clay. Cuts very easily by hand with a few turns, or put in a pin vise for a better grip. First drill a pilot hole for an azure (a light hole) and then cut the seat with the bur. Stone table should sit below the surface by a small amount so the clay shrinks around the girdle. Choose the bur that matches the stone size you wish to set. To set stones in fired metal, install bur in a flex shaft and lubricate with Cut Lube and slow speed. Top quality burs should be treated with care. Do not overheat with high speed or the bur will lose it's ability to cut.