Zn present in the alloys influence the microstructure in terms of decreasing the amount of lamellar eutectic structure and supporting the formation of degenerated eutectic structure, which coincides with higher tarnish resistance in as-cast state. Si additions play an important role, leading to a completely modified lamellar microstructure which coincides with an increase in tarnish resistance of sterling silver alloys; the lamellar eutectic structure is transformed into a predominantly continuous Cu-Si structure.