White Gold - Chemical Composition, Mechanical Properties and Common Applications

Topics Covered

Introduction
Chemical Composition
Manufacturing Process
Applications
References

Introduction

White gold has become a popular alternative alloy for wedding rings and other jewelry. White gold is a gold alloy of at least one white metal (normally palladium, manganese or nickel) and gold. The purity of white gold is provided in carats similar to yellow gold.

The characteristics of white gold differ based on the materials and the proportions of these used. Consequently, white gold alloys find applications in a number of fields. The term 'white' does not just refer to a pure white color, but also encompasses colors such as tinted brown, pale yellow and even pale rose. The off-white colors are often enhanced by rhodium plating.

Chemical Composition

The composition of white gold is shown in the table below:

Element Percentage
Gold ~90%
Nickel, Palladium, Manganese ~10%

Copper may be added for improvement in malleability. Gold-palladium silver and gold-nickel copper zinc are used in the jewelry industry. Nickel and palladium behave as primary bleaching agents for gold and zinc behaves as a secondary bleaching agent to improve the color of copper.

Variations In Alloys

White gold is manufactured by alloying other metals with yellow gold. Most commercial alloys are zinc, silver, gold and nickel however platinum is also used. White gold is available only up to 21 carat so as to retain the white color.

There are several varieties of white gold. Palladium and nickel are the top two gold bleachers; zinc and silver are the next two best elements to bleach yellow gold white. Plating yellow gold with rhodium may also help it to turn white. In case copper is added to the alloy mix, the piece has to rhodium plated.

According to certain bench jewelers, alloying gold with nickel results in a cold white color and is tough to work with. When palladium is used as the alloying metal,., the size setting will be relatively heavier, due to palladium's comparatively high specific gravity, and hence the setting will be made more expensive.

Applications

Gold-nickel alloys are strong and hard and are often used for pins and rings. Gold-palladium alloys are pliable, soft and good for white gold gemstone settings, sometimes with metals such as platinum, silver and copper for durability and weight.

Jewelry is the most popular application for white gold. This includes necklaces, earrings, rings and belts. 

References

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