White gold is white. Period. It isn’t white because it’s plated.
Usually, yellow gold is plated with rhodium, and it does have to be replated.
High carat and pure gold, that is 22K and 24K (24 is pure afaik) is always pure dark yellow-22K’s colour varies by what it’s mixed with (and I have seen and own a ton as 22 & 24k gold jewellry is the standard for the middle east and south asia). For instance, my wedding necklace is alloyed with a little bit of copper giving it a pinkish tinge. Some of my other 22K gold jewellry is alloyed with other metals, I think mostly silver. My 24K gold is a very dark yellow. Jewellry that pure is terrible for rings-it’s way too soft. Half my regular jewellry has to be remelted and fixed every few years because it gets dents in it.
My understanding of white gold is the same as Hello Again-it’s usually alloyed with something like nickel to produce a whitened effect. I would warrant that jewellers most likely coat an 18K gold ring with the whitened alloy to produce the look of white gold.
I actually googled it to check before I write this post and everything I find matches up with my and Hello Again’s understanding-where are you getting that yellow gold is alloyed with something to make it yellow samclem? I’ve got pounds of the stuff, pure or near pure, and it bears no semblance to what you’re talking about.
Looks like they do plate it with rhodium. I assumed they’d be plating regular low carat gold with the white gold alloy, about which I was incorrect. Also sorry-I meant, what evidence is there that yellow gold is plated?
Symbolism matters–else why bother with a ring at all? My husband and I opted for stainless steel wedding bands (and they were harder to find 10 years ago!) because we think we have a stainless steel type relationship–solid and practical and everyday.
people love platinum because they fell victim to the establishment.
Damn the man!
Seriously though - this is a fashion choice, and we all just become fashion victims sometimes - the supposed virtues of a particular item are extolled, the prices are jacked to make it appear more valuable than it is, and like the emperor with invisible clothes, we buy in to it.
It’s a matter of taste and little more. Do you like shiny yellowish stuff or shiny mirror-ish stuff?
I’ve always preferred the way silver (or platinum) looks and, in a fit of poetic excess, once remarked to my boyfriend at the time, “silver is the most beautiful, it looks like polished fog.”
Almost as an afterthought, by way of comparison I added “and gold? It looks like … polished urine.”
I wasn’t really serious about the latter comment, but I meant the former quite sincerely.
Of course, said boyfriend remembered the latter and teased me repeatedly for being so weird as to say that, while totally forgetting my real comment about the look of silver.
So I’ll say it again for posterity: the color silver is beautiful because it looks like polished fog.
CairoCarol, I am not fond of silver jewelry and prefer gold, but I love your description here. You are absolutely right. If one could polish fog, it would look like silver. 
I would choose silver or platinum for an engagement ring setting for two reasons, the first being that I am allergic to gold and the second being that silver goes better with my skin tone.
I just like shiny. 
Is Palladium just as heavy?
I didn’t say it was white because it was plated, I said it was shiny because it was plated. White gold is dull in its natural state. It is extremely unusual, in the U.S., to have white gold of relatively modern manufacture which is not plated in rhodium.
I don’t know about other countries. In Europe, white gold is alloyed with Palladium quite commonly, which is much shinier than Nickel. Perhaps there rhodium plating is correspondingly less common. It is almost impossible to find gold-palladium alloy white gold in the U.S., I know because I tried really really hard…
Pd is approximately half as dense. The one jeweler I have met who perceived a difference, was an old Russian jeweler who weighed it in his palm and looked at it curiously until I explain it was Pd, not Plat as it appears. (it is stamped PD on the inside, but he wasn’t looking at it under magnification) Few jewelers (and hardly any consumers) are that perceptive about the properties of metal.
I believe on the hand the weight of Palladium is comparable to white gold.
Palladium 12.02 specific gravity
Platinum 21.5 specific gravity