Rose Gold
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.
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. These physical factors are what keep rose gold slightly less popular than white gold in the jewelry market.