White gold consists of gold with one or more silver metals, usually silver, but sometimes palladium, platinum or nickel. White gold is plated with rhodium to give it its shiny appearance. |
White Gold
What Is White Gold?
(Chemical Composition)
By Anne
Marie Helmenstine, Ph.D.
Composition of White Gold
White gold is a
popular alternative to yellow gold, silver or platinum.
Some people prefer the silver
color of white gold to the yellow color of normal gold, yet may find silver to be
too soft or too easily tarnished or the cost of platinum to be prohibitive.
While white gold contains
varying amounts of gold, which is always yellow, it also contains one or more
white metals to lighten its color and add strength and durability.
The most common white metals that form the white gold alloy are nickel,
palladium, platinum and manganese.
Sometimes copper, zinc
or silver are added. However, copper and silver form undesirable colored oxides
in air or on the skin, so other metals are preferable.
The purity of white
gold is expressed in karats, the same as with yellow gold. The gold content is
typically stamped into the metal (e.g., 10K, 18K).
THE COLOR OF WHITE GOLD
The properties of white gold, including its color, depend on its
composition.
Although most people think
white gold is a shiny white metal, that color is actually from the rhodium
metal plating that is applied to all white gold jewelry.
Without the rhodium coating,
white gold might be gray, dull brown, or even pale pink.
Another
coating that may be applied is a platinum alloy. Typically, platinum is alloyed
with iridium, ruthenium, or cobalt to increase its hardness.
Platinum is naturally white. However, it is more expensive than
gold, so it may be electroplated onto a white gold ring to improve its
appearance without dramatically increasing the price.
White
gold that contains a high percentage of nickel tends to be closest to a true
white color. It has a faint ivory tone, but is much whiter than pure gold.
Nickel white gold often does not require plating with rhodium for color,
although the coating may be applied to reduce the incidence of skin reactions.
Palladium white gold
is another strong alloy that may be used without a coating. Palladium white
gold has a faint gray tinge.
Other gold alloys result in additional colors
of gold, including red or rose, blue, and green.
ALLERGIES TO WHITE GOLD
White gold jewelry typically is made from a
gold-palladium-silver alloy or gold-nickel-copper-zinc alloy.
However, about one in eight
people experiences a reaction to the nickel-containing alloy, usually in the
form of a skin rash.
Most European jewelry
manufacturers and some American jewelry manufacturers avoid nickel white gold,
since alloys made without nickel are less allergenic.
The nickel alloy is most
often encountered in older white gold jewelry and in some rings and pins, where
the nickel produces a white gold that is strong enough to stand up to the wear
and tear these pieces of jewelry experience.
MAINTAINING THE PLATING ON WHITE GOLD
White gold jewelry that has a platinum or rhodium plating
typically can't be resized because doing so would damage the coating.
The plating on jewelry will
scratch and wear over time.
A jewelry can re-plate the item by removing any stones, buffing
the metal, plating it, and returning the stones to their settings.
Rhodium plating
typically needs to be replaced every couple of years. It only takes a couple of
hours to perform the process, at a cost of around $50 to $150.
Gold
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