Decorative composite body having a transparent, electrically conductive layer and a solar cell

A decorative element, for use as an energy source and an input interface, comprising:

• (a) a transparent gemstone with a faceted surface comprising convex curved regions,
• (b) a transparent electrically conductive layer applied to said faceted surface comprising convex curved regions,
• (d) a photovoltaic cell,
• (c) a wavelength-selective layer applied
• (c1) to a planar side opposite to the faceted curved surface, or
• (c2) to the photovoltaic cell (d);
• and
• (e) a touch-sensitive electronic circuitry comprising a capacitor;
• wherein, in use, touching of the electrically conductive layer changes a capacitance of the capacitor and triggers a signal.