Abstract: A method and apparatus for sorting and centering unfinished gem stones for working in an automatic working machine includes the steps of viewing the stone in a direction parallel to the axis of centering and providing an image corresponding to the circumference thereof, superimposing the image on a reference center image, providing a reference circumference shape centered about the reference center, changing the relative size of the reference shape, preferably by computerized means, until it can fit within the image of the stone, and moving the stone until it is centered about the reference center.

Abstract: A dop for handling a gemstone comprising an elongate shaft having shank and gripper portions located at respective ends thereof, a shaped portion about the shaft defining a plurality of externally sensible features for providing information uniquely identifying the dop and establishing its spatial orientation and that of the gemstone.