What color of gold should you use??
As far as nature is concerned there is only one answer, gold colored. There is no such thing as white gold or rose gold in nature, it is all the same color, gold.
Today there is an extremely high demand for 'white gold'. Many people believe this is a natural option. The true demand for this white color comes from two other metals, platinum and silver. The cost of silver is very low but it will need cleaning as it will tarnish over time. Platinum will not tarnish but cost even more than gold.
White gold was created to be able to sell people a white metal that does not tarnish at a lower price than Platinum. A keen marketing idea as people would pay the same or even more for it than traditional gold while the cost of this new alloy was far lower than normal gold alloys thus boosting profits. This keen idea came with a number of problems, however. To become white, this gold was alloyed with a large amount of a base metal, nickel. People are allergic to base metal against their skin. To further complicate matters, the white color from a nickel gold alloy is not pretty as it is more accurately described as gray gold, a marketing plan doomed to failure. So the keen marketing idea of 'white gold' had two problems to overcome, people were allergic to it and it was ugly. They needed to somehow sugar coat this monster in order to sell it thus they came up with the idea that it would be plated with Rhodium, one of the members of the Platinum family.
Rhodium is an extremely expensive metal, far higher than plain platinum but plating uses only a tiny amount so the cost is negligible. It is a very strong metal and is also very chemically resistant. A thin plating of Rhodium over the unappealing white gold makes it look gorgeous thus many people then selected 'white gold' as the color of choice in their gold jewelry. A considerable amount of market trickery was employed and jewelers got richer. It is still going on today.
Ironically, the same Rhodium plating over silver keeps silver from tarnishing and looks and wears exactly like the finished nickel white gold jewelry and at a small fraction of the cost, PLUS the silver is much less likely to create an allergic reaction as the nickel white gold is likely to once the plating wears off AND the silver looks whiter and prettier than the nickel white gold after the plating wears off. Hmmmmm.
Plating always wears off, regardless of what it is, so any plated jewelry needs to be returned to the jeweler periodically for a new 'dip'. Often they will do this for 'free' or just a small cost. Many times customers will make a new purchase with this new visit to the store so this is a win-win situation for the jeweler as it requires little skill to plate something once you are set up to do it.
In European countries where more people had a problem with the allergic reaction to the nickel gold a new white gold was created, palladium white gold. Palladium is a precious metal, unlike nickel which is a base metal so this is a step in the right direction, it would seem. The cost is much higher than nickel white and is even much higher than traditional gold alloys but there is much less allergic reactions with palladium compared to nickel, however, the old problem remains that the color is just too gray. The finished project has little eye appeal as it is not as white as even the inexpensive silver thus the same solution is again employed, rhodium dip.
Can you see the difference in plated jewelry versus non-plated by your eye? Most people can spot it very easily. All our lives we have seen cheap costume jewelry plated with gold, silver and rhodium and many people automatically think 'cheap' when they see that plated look. Nothing can look so elegant as a high polished piece of precious metal, plating can never hope to duplicate that solid dazzling shine. Plating cannot be polished as it will simply wear off so once it is plated it is 'done'.
Now what about rose gold, also called pink gold or red gold? This is simply a gold alloy with a lot more copper and less silver. Copper is the lower grade of the metals used in traditional alloys. When it is increased it will have a redder color but will also give more people an allergic reaction and may tarnish a little as well. It is very pretty all by itself, however, so it requires no plating.
Ever hear of green gold? It is more of a light yellow as it contains only two metals, gold and silver. In 18k it is great to work with as a smith and a purist but the paler color is not popular.
The color of gold most people are used to seeing in the USA is really 58.5% gold with the remainder split between silver and copper. This is 14k yellow gold. The color is improved by adding more copper and less silver but this also makes it more brittle, more likely to tarnish and difficult to work with so in general the remaining 41.5% is split evenly with silver and copper producing a rather washed out gold color.
People are generally pleasantly surprised to see traditional 18k gold alloys as the color is more golden than the 14k they are used to seeing. Traditional 18k is 75% gold with the remaining 25% being half silver and half copper.
My gold smithing instructor makes jewelry for Thai people and generally uses almost pure gold such as 23k which contains over 90% gold and a small amount of silver. It is a very rich golden color and is often thought of as too soft by American standards but almost all Thais wear it and most Thais wear their gold everyday. There is virtually no demand for white gold here as these people believe that the more gold color their gold is, the better. They do not wear 14k and very little 18k. They could never accept the idea of mixing cheap copper into any of their gold. Some prefer silver, however, and some Rhodium plate their silver.
Perhaps I have thrown a tiny wet blanket over the current white gold craze by writing this but in the jewelry business I believe that full disclosure, whether it be about gemstone treatments or metal treatments is simple honesty. I believe many people have been misled about their gold and that is disturbing. Educated customers are happy customers that come back to buy more because they know what they are getting and are making an educated choice.
Wear your jewelry in good health, Lee