Lost Wax Casting Conditions with Tourmaline <i>In Situ</i>

Abstract

The technique of stone-in-place casting has been established in jewelry production for three decades. However, the process is not widely used since it is limited to precious stones with high hardness and high stability at high temperature. This experiment tested tourmaline, which is a semi-precious gemstone having less hardness and less stability compared with precious stones. The objective was to achieve the conditions of a lost-wax casting process with tourmaline placed in waxes in the casting process. The experiment was divided into two parts. The first part was to understand the tolerance of tourmaline under the heating conditions. Natural tourmaline stones were investigated and compared inclusions tested at a temperature of 700°C. Tourmaline with ion-implantation was also heated to 700°C for comparison. The second part was to test tourmaline in-place casting with tree conditions of flask casting at 550°C, 625°C, and 700°C. The results showed that stones were able to tolerate as much as at 700°C. The inclusion growth of ion-implantation under heating to 700°C also observed the growth of inclusion in the same way as untreated tourmaline. The casting condition at 550°C showed better results. The highest probability of stones breaking after casting occurred in bezel settings.