10K is 41.6% PURE GOLD the rest of the material are alloy metals such as copper silver zinc etc… , if you have skin sensitivity to those other alloy metals then your skin will react to it. The earrings and your skin and oils reacted to the metal which is why it’s that color, it needs to get cleaned. You should probably not wear 10k and wear 14k instead as 14k would be 58% pure gold. People with skin sensitivity can only wear 14k or higher.