Gold jewelry appearance changes explained by experts

Experts have clarified why 18K gold jewelry may undergo changes in appearance, such as darkening or losing luster. While pure gold is highly resistant to corrosion, 18K gold is an alloy containing other metals like silver, copper, and zinc to increase durability for daily use.

According to jewelry specialist Igor Ferreira of Fábrica do Ouro, visual changes do not necessarily mean the gold is illegitimate. Research published in the Journal of Analytical Atomic Spectrometry indicates that when these alloys are exposed to certain chemical compounds, such as sulfides in the environment, the secondary metals like silver and copper can form thin surface layers of corrosion.

These surface reactions explain why a piece might appear to darken, but the change is typically limited to the exterior layer and does not imply the gold itself has disappeared or lost its value.