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White Gold?
What are 'white golds'? Are they a
special form of gold? Do they contain gold or are they silver? These
are typical questions often asked.
White gold is not a special form of
gold. White gold is true carat gold, just like yellow carat gold
jewellery.
The white colour is achieved by a careful choice of the
alloying metals which bleach the deep yellow of pure gold.
White golds for jewellery were developed
in the 1920's as an affordable substitute for platinum. Nowadays,
they are a jewellery metal in their own right and are currently very fashionable
and desirable.
White golds can be produced up to 21 karat. They are
often used in settings to enhance diamonds and other gemstones. White gold
bridal jewellery is increasingly popular.
Fallacies
Higher karat makes the gold whiter.
Gold is yellow - period. At 18Kt 75% of the item must be gold
(yellow), the remaining 25% can be other metals. The higher the karat the
less room to add other metals that change gold's colour. Saying for
example, that 19Kt white gold is the answer - is nonsense. It's what we
add to gold that effects its colour - not the amount of gold.
The reflective chrome like colour you see in new jewellery is the
actual colour of the item.
No. What you see in a showcase is rhodium plated jewellery. The
plating will wear off, what colour or shade that is underneath depends on the
gold alloy of the item. It will however, not be that reflective mirror-like chrome looking metal.
Changing Gold's Colour
There is no white metal. There are only two coloured metals gold (yellow)
and copper (red). All other metals are a shade of gray.
As every schoolboy (and girl) knows, mixing yellow and blue produces green and
mixing yellow and red produces pink. With metals, we only have the choice
of mixing yellow (gold) with red (copper) or gray (all the other pure metals).
Adding copper to gold makes it redder and adding silver, zinc and any other
metal makes gold paler. Thus, with lower carat golds, we can add more
alloying metals, and can have a wider range of colours than the higher carat
golds.
At 22 karat (91.6% gold), we can only add a maximum of 8.4% of alloying metals
and hence can only obtain yellow to pink/rose shades. At 18 karat (75.0%
gold) and lower, we can add 25% or more alloying metals and hence get colours
ranging from green through yellow to red, depending on the copper: silver plus
zinc
ratio.
Making Gold
White
Making gold white is similar to mixing colours in paints. Alloying metals
to gold, apart from copper, will tend to whiten the colour and so it is possible
to make carat golds that are a reasonable whitish colour.
Whilst additions of any gray metal to gold will tend to bleach it's colour, in
practice, nickel and palladium are the best strong 'bleachers' of gold.
Silver and zinc are moderate bleachers and all others are moderate to weak in
effect.
In colouring gold there is a greater challenge involved. Varying the
colour also changes other properties, such as hardness and strength, necessary
for jewellery.
Nickel and Palladium White Golds
There are two basic classes of white
gold for jewellery. The Nickel-whites, where
 nickel
is the major ingredient in the alloy and the Palladium-whites, where
palladium is the major ingredient in the alloy.
The nickel-whites tend to have a colder white colour, whereas the palladium
whites have a warmer colour. Good nickel whites tend to be hard and
difficult to process.
Good palladium-whites tend to be soft, easy to
process (but lost wax casting is more difficult) but are much more expensive,
because of the price of palladium.
The vast majority of white golds on the North American market are nickel-whites.
Nickel Allergy Problem
Unfortunately about 12-15% of people, the female population especially, are
allergic to nickel in contact with the skin and this gives rise to a red skin
rash or irritation. This problem applies to costume/fashion jewellery,
white gold and steel jewellery, zippers and fasteners and other body piercing.
The European Union countries have enacted legislation (under the EU Nickel
Directive) in January 2000 that limits nickel release from
jewellery and other items in close and constant contact with the skin. Thus, in
Europe, nickel white golds are being phased out and being replaced by palladium
white golds.
Japan and China have taken a similar position on nickel. Canada and the
USA and other countries are taking a more relaxed approach to this issue. Nickel in
jewellery and nickel white golds are the prominent in the market because they are
cheaper to produce and suitable to make jewellery. For a further
discussion of nickel allergy
click here.
Rhodium Plating
White gold and often silver and platinum jewellery are plated with rhodium.
There is no legal or industry-accepted definition of what constitutes 'white'
colour in golds.
For good technical and economic reasons, many commercial white golds are not a
good 'white' colour. They are usually a yellow-brownish tint and are
usually rhodium-plated to improve their appearance.
Rhodium is one of the platinum family of metals. It has a high
reflectivity and a good metallic white colour and is hard with good wear
properties. A thin electroplated coating is applied to white gold
jewellery to improve its white appearance.
This is legally allowed. Such a coating, if not subjected to undue
abrasion or heat of repairs, could have a lifetime of 1-3 years before it wears
through to reveal the gold alloy underneath.
For many consumers, the colour of rhodium has become the norm for the colour of
white gold, because that is what they are used to seeing on jewellery described
as white gold.
Buying White Gold Jewellery
White gold jewellery sold in North America probably contains nickel.
Sensitized
 people
may find that they react to such jewellery.
Even conforming to the EU directive is no guarantee that these alloys will not
cause an allergic reaction, as some nickel is still allowed.
Check with your retailer that the alloy is 100% nickel-free. CanadaJewels now offers a new 18Kt white gold-palladium alloy,
PureWhite™,
guaranteed 100% nickel free.
Rhodium-plating should provide some limited protection, but remember
electroplating is porous and will, in time, wear away.
White gold jewellery wearers can be disappointed to discover that their
jewellery has gone off-white, even a yellow-brown tint, as the rhodium plating
wears through (some cheaper jewellery may well be distinctly yellow-brown in
colour).
There is currently no legal requirement for a retailer to inform purchasers that
the jewellery is rhodium-plated.
Purchasers should always demand to know if their jewellery is rhodium-plated.
If the jewellery is rhodium-plated you cannot know how white (or not) the gold
alloy underneath.
CanadaJewels will provide you with information of the nickel content in
all the white gold products we carry.
Care of Rhodium Plated Jewellery
Rhodium Plating provides protection for your sterling silver and white gold
jewelry by coating it to help prevent tarnish and surface scratches. A
rhodium finish however is not impervious to the effects of wear and abrasion
that may occur in everyday use.
To limit wear, one should avoid
household cleansers, gardening and other activities that can quickly destroy the
rhodium plating, thus exposing the slightly yellow tint.
Even talc, which is found in many cosmetics, is known to have an abrasive effect
on jewelry items. White gold may appear slightly yellow. Sterling silver may
tarnish.
Most jewelry can simply be re-plated with rhodium at a minimal cost.
CanadaJewels for example charges $30-$50 to rhodium plate a ring. The plating on
pendants and earrings lasts longer than rings since they are not exposed to a
much friction.
Tips to keep your Rhodium Plated jewelry looking its best
Do not use any abrasive cloths for polishing
Do not use chemical cleaners
Clean only with mild soap and water
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