There is no such thing as white gold:
There are gold alloys which appear white, silvery, or grey.When jewellers speak of white gold, they mean white gold alloys. In most other major languages these alloys are described as grey rather than white..
White Gold Alloys with Nickel :
White gold alloys became fashion 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."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. 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.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.
Gold Alloys :
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, 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
