Sol-gel silver containing coatings have been prepared and applied upon lead crystal glass. Both un-doped and arsenic oxide-doped lead crystal glasses have been used as substrates. Arsenic oxide was introduced with different percentages as a thermo-reducing agent, with the aim to favour silver ions reduction and aggregation to form nano-sized colloids. Such silver colloids yielded a superficial yellow ruby colouring, due t o their known surface plasmon resonance band in the visible range (~420nm). The influence of the experimental parameters to obtain yellow ruby colouring (percentage of arsenic oxide in the lead crystal base glass; silver content of the coatings precursor sol; coating thickness; atmosphere, spectroscopy (absorption and transmission). Colour coordinates, dominant wavelength and colour purity percentage were calculated from the corresponding transmission visible spectra. The role of the thermo-reducing dopant (arsenic oxide) is essential for obtaining superficial yellow colouring. The higher the percentage of arsenic oxide, the higher the intensity of the yellow colouring. When the silver content of sols increased, the same tendency is observed. Thermal densification fo the sol-gel coatings have to be carried out under oxidising atmosphere, since heat-treatments performed under reducing atmosphere yielded grey-brownish colouring, due to reduction of the lead from the base glass. Optimum conditions for obtaining superficial yellow ruby colouring on lead crystal glass were selected.
