or wire wrapping these selected circumferential lengths are wrapped with much shorter joining lengths of wire then these circumferential lengths of wire are wrapped around the section of the mandrel having dimensions most closely matching the circumference of the cabochon with the joining lengths of wire each being disposed in a retention groove 38 formed into each forming cylinder typically each retention groove has a depth of between 0 03 u2033 and 0 15 u2033 and a width of between 0 03 u2033 and 0 25 u2033 and serves to hold the joining lengths of wire in place as the cabochon cage is wrapped after a preform cage has been formed a bail if desired is formed at the ends of the circumferential wrapping wires the preform wrapping is removed from the mandrel and the cabochon is placed within the preform cage and the upper and lower most circumferential wires are reformed inwardly to trap the cabochon within the cage securely preferably the ratio of diameters of the elliptically cylindrical forming surfaces will be between about 1 2 1 to about 2 0 1 or the eccentricity of elliptical surfaces will vary between about 0 55 and about 0 9 more preferably the ratio of diameters will be between about 1 3 1 and 1 8 1 or the eccentricity will be between about 0 6 and 0 85 it is preferred that the circumference of each succeeding forming cylinder will exceed that of next smaller forming cylinder by between about 0 2 and 0 9 inches more.