Abstract: The present invention relates to a covering element for a portable object made of a first material, the first material being a ceramic material having a first color, characterized in that the surface of said covering element is at least partially treated so as to exhibit at least one conversion having a different color from the first color.

Abstract: An external element of a timepiece or a piece of jewelry includes a body made of an insulating ceramic material, the body including a housing, a wireless communication system disposed in the housing, and at least one part of a surface of the external element includes a layer of metallic visual appearance, the layer being obtained by carburization, nitridation, or a combination of carburization, nitridation.

Abstract: The present invention concerns a method for obtaining a finished or semi-finished zirconia-based article (1), the article having a metallic external appearance and non-zero surface electrical conductivity, characterized in that the method includes the steps consisting in: taking at least one zirconia article, pre-shaped in its finished or semi-finished form; placing said article inside a chamber (10) in which a gaseous mixture is arranged, this gaseous mixture including at least a first hydrogen and carbon based gas compound in a first concentration (C1) and a second hydrogen and nitrogen based gas compound in a second concentration (C2); heating the gaseous mixture until the molecules of the first and second compounds dissociate and keeping said article in the reactive atmosphere thereby created to obtain diffusion of the carbon and nitrogen atoms in the external surface (2) of said article and to form stoichiometric carbonitride (ZrCx—Ny) at the surface, and prior to the step of heating the process gases

Abstract: An external element made from a first material for a wearable object, the first material being an insulating ceramic, wherein a surface of the external element is at least partially treated to include at least one conversion with an electrical conductivity.

Abstract: The present invention concerns a method for obtaining a finished or semi-finished zirconia-based article, the surface of the article having a metallic external appearance and non-zero surface electrical conductivity, wherein the method includes the steps of: taking at least one zirconia article, pre-shaped in its finished or semi-finished form; placing said article in a chamber in which a hydrogen and carbon/nitrogen gas mixture is heated; heating said article and the gas mixture using at least one resistive element traversed by an electric current to obtain dissociation of the hydrogen and carbon/nitrogen based gas molecules and an increase in the temperature of said article; keeping said article in the reactive atmosphere thus created to obtain diffusion of the carbon/nitrogen atoms in the external surface of said article.