What is cu on jewelry?

In jewelry, "Cu" refers to copper, a metal often used in alloys to enhance the properties of other metals like gold and silver. Copper improves durability and resistance to tarnish while also adding a warm reddish hue. It's commonly found in metals like rose gold, which is an alloy of gold and copper. Additionally, copper can cause skin reactions in some individuals, so it’s essential to be aware of any Allergies.