Abstract: A process for producing a part containing an embedded pattern includes preparing a first and a second substrate, at least one of which is transparent, wherein preparing the first substrate includes forming at least one trench in a surface thereof, the surface being a surface intended to be bonded to the second substrate; joining the first substrate and the second substrate by molecular bonding, the trench bounding a hollow volume that defines the embedded pattern, the hollow volume communicating with an exterior of the joined first and second substrates; and causing a fluid dye to flow in the hollow volume in order to dye at least certain walls.