An electronic device may include conductive structures having a visible-light-reflecting coating. The coating may include a seed layer, transition layers, a neutral-color base layer, and an uppermost layer that forms a single-layer interference film. The neutral-color base layer may be opaque to visible light. The interference film may include silicon and may have an absorption coefficient between 0 and 1. The interference film may include, for example, CrSiCN or CrSiC. The composition of the interference film, the thickness of the interference film, and/or the composition of the base layer may be selected to provide the coating with a desired color in the visible spectrum (e.g., at blue or purple wavelengths). The color may be relatively stable even if the thickness of the coating varies across its area.