Despite silver being incredibly durable, it can tarnish really easily, which can reduce the value and look of the jewellery. Therefore, the metal is plated with a very thin layer, only one to three microns thick of precious metals that do not tarnish. These metals mostly include such materials as platinum, rhodium and even gold. Although this might reduce the purity of the silver, it actually increases the value of the jewellery since these metals are in fact more precious than silver.