Tube Setting Tube-Set Diamond in a Vintage French Ring. Tube-Set Diamond in a Vintage French Ring. (Side View) Tube-Set Diamond in a Vintage French Ring. In a tube setting the stone is placed inside the open end of a precious metal seamless tube with the same inside diameter as the diameter of the stone. The tube is soldered to a base or placed inside a hole and soldered. Tube-Set Diamond in a Vintage French Ring. Tube-Set Diamond in a Vintage French Ring. (Side View) Tube-Set Diamond in a Vintage French Ring.