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|What is White Gold and Where Does It Come From?|
Gold itself is a yellow metallic element but, in its pure form, it is too soft to be used for general jewellery purposes, although there are some cultures which do wear pure gold jewellery, it would need to be heavily made and carefully used. The yellow colour of gold is caused by gold absorbing violet and blue light, but reflecting yellow and red light.
It is usual for gold to be mixed with other metals to produce an alloy, which is simply a mixture of two or more metals. Throughout history, most people have preferred the colour of gold jewellery to remain close to that of pure gold itself, and so most jewellery has historically been made using yellow gold alloys. Other metals mixed with gold to produce alloys include copper and silver, which are the common components of most yellow gold alloys, and nickel, zinc, and palladium to produce white alloys.
White Gold Alloys with Nickel
White gold alloys became fashionable in the 1920's, mainly as a substitute for platinum, which had itself recently become fashionable. Platinum is quite expensive, needs greater temperatures than gold, and is generally considered harder to work with than gold, although it is ideal for use in diamond settings. At least three patents were issued for different "recipes" of white gold alloys during the 1920's, using different components to produce the whitening or "bleaching" effect. Simply mixing a white and a yellow metal together does not just produce a pale yellow colour, alloying produces a difference in the atomic structure which alters the reflectivity of light of different wavelengths.
The commonest metal which causes a significant bleaching effect in gold is nickel, which has the great advantage of being inexpensive, and also providing, in 18 carat alloys, a good colour match for platinum, however its colour matching in 14 and 9 carat alloys is poor. It also has the serious defect that it commonly causes dermatitis, through allergic reactions when worn in contact with the skin. It is also considered to be slightly carcinogenic. E.C. Regulations covering the use of nickel in jewellery are being implemented, and soon all or most new jewellery sold in the Community will have to be nickel-free, or at least "nickel-safe". Most American and Italian white gold alloys use nickel.
A typical nickel containing white gold alloy might be, in parts per thousand:
Gold 750, Copper 55, Nickel 145, Zinc 50
White Gold Alloys with Palladium
The other metal which is ideal as a constituent of white gold alloys is palladium, which is a close relative of platinum. Its main disadvantage is that it is quite expensive, indeed at the time of writing this, the market price of palladium was higher than that of gold, due to Russian economic and production problems. Its second disadvantage is the high melting point, although jewellery manufacturing and repair equipment has improved, so that most workshops can now cope. A hidden factor in the high cost of alloy components is that there are large proportions of scrap produced during jewellery manufacture. Because this involves expensive precious metal alloys, recycling and reclamation of the precious metals is very important. When scrap contains high levels of expensive metals like palladium, there are extra costs involved in recovering it, which have to be added back to the production costs.
Other possible whiteners include silver, platinum, chromium, cobalt, tin, zinc, and indium. Silver would be an ideal constituent, with excellent working properties, but unfortunately it does not have a very great bleaching effect. Copper does not tend to whiten, but is used to improve the ductility of most white gold alloys.
A typical palladium containing white gold alloy might be, in parts per thousand:
Gold 750, Silver 40, Copper 40, Palladium 170
We Use Nickel-Free Palladium White Gold
We use 18 carat white gold alloys for most of our diamond ring settings. Our policy is to use only white gold alloys containing palladium, and which are nickel-free.
Black Humour or a White Lie?
I normally answer questions seriously, but do have a rather keenly developed sense of humour. Once a nice couple asked me the usual questions about white gold, and I started with the slightly facetious answer that most gold was yellow, and white gold was very rare. I then explained that it was only found in small quantities in certain mines. By this stage, both of them had nodded and followed the plot, so I was encouraged to continue. Most gold comes from South Africa, and most of the mine labour is performed by low paid black workers. The white mine workers are usually highly paid managers, supervisors, and technicians. The problem with white gold is that it could become stained by perspiration from the black miners, and this ruined its marketability. Therefore white gold seams could only be worked by the highly paid white workers. I managed to continue inventing this mythical scenario expecting them to realise soon that I was leg-pulling, but they continued to nod and make understanding sounds.
Coming to the end of about five minutes of sheer invention, they then said "Is that right", and I laughed and said "No, not a word of it, but you seemed to be enjoying the story, so I carried on!" I'm glad to recall that they joined in the amusement, and I then gave them a more accurate account. I find it intriguing to wonder what would have happened had I left them believing the original story.
You may wish to visit some of our other pages:-
Allergies to Gold Jewellery
Gold Alloys by Weight & Volume
Hardness & Durability of Gold Alloys
White Gold Turns Yellow - and Why
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