There are some interesting myths I hear about white gold, so I thought I would do a blog post to help explain all about it.
White gold is made up of a mix of gold and other white metals, sometimes platinum, palladium or rhodium and sometime tiny amounts of copper and zinc. It is worth saying that gold is yellow, that is the colour it comes out of the ground. White gold is a material we create. So 9k white gold is 37.5% gold and the rest is white metals. 18k white gold is 75% gold and the rest other white metals.
So if you have an 18k white gold ring and cut through it with a saw, the metal is white throughout. It is not yellow centered and white shell.
So, this mix creates different "whiteness". Just like mixing paint, a bit more white metal makes a whiter finsh. Hence 9k white gold is white with a hint of cream. 18k white gold is quite grey in colour, due to the colour mix. Neither metal has the "whiteness" of silver. This is the reason all high street 18k white gold and some 9k white gold is rhodium plated - to give the bright white colour. This is not always explained to customers.
So what's the problem? Well if this is explained at the time, you'd know to expect the plating to wear off in a few years. Visually, it looks a little dull and brown/ yellow in colour. They should explain that you can take it back and get it re-plated. Often they don't.
I often hear white gold is yellow gold with rhodium plating. This is a myth. When the plating wears away the colour you see, that I mentioned a moment ago, can give the illusion of yellow gold coming through. This is not true.
Rhodium plating is done to create the white colour, for aesthetic reasons. Some people still believe it is to avoid allergies. For many years in the UK nickel was mixed with gold to make "white gold". Though it was known to create allergies so plating was used as a barrier between metal and skin. Nickel is now banned in all UK metals, though many counties still allow it to be used. This is one of the reasons jewellery purchased overseas can create allergies. If you buy UK white gold, it will not create an allergic reaction, plated or not!
I hope that explains it a little more. The image below show the colour difference between rhodium plated 18k white gold (bottom) and the natural colour of the metal (top).