Discuss Stevo's answer to: My inexpenseive gold earring turned silver in two wearings - how did that happen? Has also happened before.

Your jewellery is inexpensive because the vast majority of the item is a basic cheap metal. To make the item look gold either a metallic paint or electrolysis is used to coat the base metal. As this outer layer is extremely thin it can easily wear off in a very short time, especially if the item is handled, knocked about or worn.