What are the properties of white gold and rose gold?
In essence, there is only a slight difference between the different alloys of gold.
A gold alloy is simply gold which has been combined with other metals in order to change its color, as observed with rose gold and white gold.
18k white gold is basically 24 karat gold combined with one other white metal such as palladium or nickel. A typical mix comprises 17.3% nickel, 2.2% copper, and 5.5% zinc. 9k white gold is typically a mixture of gold and 62.5% silver.
When copper (which is reddish in color) is combined with gold, the end result is rose gold, and the depth of the color will depend on how much copper has been added to the gold. Typically, the greater the content of copper, the more red the hue of the final alloy.
How pure gold is measured, is in karats. One karat is 1/24 gold. Therefore, 9k equals 9/24 gold (which equates to a percentage of 37.5% gold), whilst 18k equals 18/24 gold (which equates to a percentage of 75% gold). Of course, 24 karat gold is 100% gold.
Based on these fractions, 9k white gold is therefore ‘whiter’ than 14k, and even more so than 18k white gold. This is because there is a lower amount of gold to mask in 9k white gold compared to 14k and 18k white gold.
The quality of white gold may differ, contingent on the proportions and metals that have been used in the mixture. The varying proportions are intentionally different, for specific purposes. As an example, when gold and nickel are mixed, the end product is hard which is more ideal for rings. Conversely, a mixture of gold and a soft metal (eg, palladium) is ideal where flexible gold is required, such as for gemstone settings.
Given that both white gold and rose gold are comprised of gold merged with other metals, there is no such thing as “pure” (100% or 24k) white or rose gold.
Some unusual gold alloys are gold combined with iron, silver, aluminium or cadmium. This is where one might hear of purple, green or even blue gold. Although these variations are not often seen, they do exist.