Gold Color
The addition of alloying elements (other metals) to gold are used to increase the toughness and hardness of the metal, as well as change the color. Adjusting the proportions of coloring agents provides the array of colors on the market. Additional metals enhance properties such as castability, grain size, hardness, corrosion resistance, color, workability, ultimate strength, and others. These additions can dramatically change the properties of the karated metal for better or worse.
For example: 18 karat rose gold is 75%, or 18 parts fine gold and 25%, or 6 parts copper. It is the rich red copper combined with the pure yellow gold that creates a warm rosy tone. 14 karat white gold is 14 parts gold and 10 parts white metal, either nickel or palladium. These white metals dominate the color, creating a warm gray tone.
Typical metal used to achieve the desired gold color are:
Copper - Reddening
Silver - Greening
Zinc - Bleaching
Nickel - Whitening
Palladium - Whitening
Examples are:
Yellow Gold: copper, silver, zinc
White Gold: copper, nickel, zinc
Red (Rose) Gold: copper
Green Gold: silver