Although they are often used interchangeably, the difference between red, rose, and pink gold is the amount of copper used in the alloy. Commonly found in jewelry, 18-karat rose or "pink" gold is an alloy usually produced by mixing 75% gold, 16% copper and 9% silver together. This type of gold alloy is very fashionable and is typically the type of copper/gold alloy found in jewelry. Red gold typically has a higher copper content and comes in deeper, darker hues. Unfortunately, the high copper content can cause some allergic reactions, although it is not as common to have allergic reactions to rose gold as red gold.