Colored watch glass

A timepiece comprising a watch case and a transparent timepiece component which is a watch glass assembled with the watch case, the watch glass comprising:

• a substantially planar or curved interior surface, the interior surface being oriented towards an inside of the watch case,
• an exterior surface opposed to the interior surface, the exterior surface being oriented towards an outside of the watch case,
• a peripheral lateral surface linking the exterior surface and the interior surface, and
• mainly a transparent material, wherein the transparent material is an inorganic and/or mineral material or a material composed at least partially of inorganic and/or mineral matter,
• wherein the transparent material is colored by a zone of modified chemical composition within the timepiece component through an introduction of at least one coloring chemical element into the transparent material, wherein the at least one coloring chemical element is selected from the group consisting of metals, metal oxides, metal compounds, metal alloys, transition metals, transition metal oxides, metalloids, non-metals, and gases,
• wherein the zone of modified chemical composition extends in only an interior surface layer having a thickness representing on average at most 25% of a total thickness of the timepiece component, the interior surface layer including the interior surface, wherein the zone of modified chemical composition does not extend to the exterior surface,
• wherein, in the zone of modified chemical composition observed from outside of the exterior surface, a color is seen as non-uniform on at least a portion of the exterior surface and/or a portion of the lateral surface,
• wherein
• (i) the zone of modified chemical composition has a uniform thickness in the interior surface layer, a watch glass coloring effect being modulated to obtain the color seen as non-uniform on the at least one portion of the exterior surface and/or the at least a portion of the lateral surface, by a color on the at least one portion of the exterior surface observed from outside of the exterior surface being seen as different as compared to a color on the at least one portion of the lateral surface observed from outside of the exterior surface and/or as compared to a color on another portion of the exterior surface, and/or
• (ii) the zone of modified chemical composition has a non-uniform thickness in at least one portion of the interior surface layer, a watch glass coloring effect being modulated to obtain the color seen as non-uniform on at least one portion of the exterior surface observed from outside of the exterior surface by the non-uniform thickness in the at least one portion of the interior surface layer.