After all, the flash of a gem depends on the facets being at the correct angle to refract and reflect incoming light. The index is attached to a faceter body and the dop slides through these with the gem waxed to it. Being an engineer, Jack decided to try to develop something like this about 20 years ago. He first begged for used laps from friends, simply recharging them as needed. Then he began using copper roof flashing from the hardware store.
Pure copper is soft enough to accept a charge of diamond dust if properly applied.
He did this by using the outside flat bearing race of a ball-bearing assembly to roll the diamond into the copper. In faceting, getting the gem properly dopped or glued to the end of the dopping stick may seem easy. If, however, this preform gem is not properly dopped and comes loose during the operation, you've got a real problem. Jack uses a metal dop with the end just slightly concave to hold the gem better. The trick here is to mount the rough gem to the dop so it stays and always sits at the same angle.