Substrate comprising a silver-plated surface protected against silver tarnishing and method for manufacturing such a substrate

A substrate comprising:

• a final silver-plated surface, the final silver-plated surface being protected against silver tarnishing by a protective coat having a thickness between 1 nm and 100 nm, said protective coat comprises a first coat of Al2O3 deposited directly on said final silver-plated surface and having a thickness between 0.5 nm and 50 nm and directly on the first coat of Al2O3, a second coat of TiO2 having a thickness between 0.5 nm and 50 nm,
• wherein the substrate includes a coat of a silver and copper alloy comprising between 0.1% and 10% by weight of copper with respect to the total weight of the alloy, forming said final silver-plated surface, said coat of a silver and copper alloy having a thickness between 1000 nm and 3000 nm, an entirety of the coat of silver and copper alloy being formed along a same first plane, and
• wherein the substrate includes a single coat of substantially pure silver deposited directly thereon so that the substantially pure silver is located between the substrate and the coat of silver and copper alloy, an entirety of the pure silver being formed along a same second plane different from the first plane.