The production of colored gold-based components (white, red, pink, blue, green, purple, yellow, etc.) is widely known but the production of multi-colored pieces (with two, three or more colors and a smooth gradient in between) in one casting step (without components soldering) is a totally new manufacturing process. This process applies to the production of gold artifacts including the jewelry field. Its main advantage is the ability to develop and produce jewelry pieces with innovative designs. The basis of the process is the production of gold-based components with a controlled color gradient. This is obtained with the control of the alloy chemical composition along the piece. The component's production will be based on an incremental process of melting and solidification. The process is essentially based on a continuous melting of the base materials by induction heating inside a mold with the addition of new elements or alloys in order to continuously change the component's chemical composition. By the control of the process variables (materials added, melting and solidification rates), it will be possible to obtain a component with the desired chemical composition gradients. The chemical composition gradient will be selected considering the aesthetic of the component and the physical, metallurgical and mechanical properties of the intermediate phases formed in the component. The end of the process yields jewelry pieces (polychromatic pieces like rings, pendants, etc.) with controlled color gradients along the component in both a micro and macro scale.

Author(s): Dr. F.S. Silva, L. Mazare, B. Henriques, D. Soares, D.