How is gold made into different colors?
Gold is yellow in elemental form, but it comes in different colors in jewelry. Colors are made by adding different colored metals to gold in a process called "alloying." An alloy is a mixture of two metals. When copper is added to gold, a pink (or red) gold results. Adding nickel produces a white gold, but there are strong drawbacks to that metal so Ricco exclusively uses an alloy of gold and palladium (details in this blog post.) There is even a green gold alloy (see an example here.) Another white metal is platinum, which is grayish, and silver, the whitest of all precious metals.