Types of Gold
Gold is one of the precious metals used in jewelry and as money. It occurs naturally in nuggets in underground veins. The quality of gold alloys used in jewelry is measured by carats, sometimes spelled karat. The highest quality is 24 carat, with qualities ranging all the way down to 9 carat. Most jewelry is 10 or 14 carat.
Yellow gold is the most common alloy, made by combining pure gold with copper and silver. Other types of gold are:
- White gold – this is an alloy of pure gold and at least one other white metal. Usually nickel or platinum is the metal of choice. When used in jewelry, it is covered with a coating of rhodium to help it maintain its luster.
- Rose gold – this type of gold is also called pink gold or red gold due to its reddish color. Because it was common in Russia, it is often called Russian gold. To make rose gold, copper is the alloy used. The amount of copper used determines the amount of red the final product contains. The highest quality of white gold is 22 ct. and is called crown gold.
- Black gold – Also known as grey gold, this is a form of gold sometimes used in jewelry. It does have a yellow color, but can range in color from white to black. Several methods can be used to produce black gold, such as Platination, which involves combining sulfur and oxygen, electrodeposition, chemical vapour deposition and by using lasars.
There is also a difference in the color of gold depending on the carat quality. In yellow gold, the higher the number carat the more yellow the color of the gold. However, in rose gold, 9 carat has a deeper rose color than 18 carat. Both 9 carat and 18 carat white gold have the same color, especially when they are coated with rhodium.