Pure gold is slightly reddish yellow in colour, but combining it with a range of metals can produce other colours.
Rose gold is a gold-copper alloy, with small traces of silver, which is widely used for specialized jewellery. Rose gold, also known as pink gold and red gold, was popular in Russia at the beginning of the nineteenth century. It is commonly used for wedding rings, bracelets, and other jewellery. Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content: the higher the copper content, the stronger the red coloration. Pink gold uses the least copper, followed by rose gold, with red gold having the highest copper content.
Green gold, also known as Electrum, is a naturally occurring alloy, made up of mainly gold and silver, with small traces of copper that can also be produced artificially. The colours range from pale to bright yellow depending on the proportions of gold and silver. Electrum was used in ancient Egypt, sometimes as an exterior coating to pyramids and obelisks. It was also used in the making of ancient drinking vessels and the first metal coins ever made were of electrum. The Nobel Prize has also been made of gold-plated green gold.