White gold is scratch-resistant, but the color fades over time, whereas yellow gold causes fewer allergic reactions, but needs more polishing. While white gold is stronger than yellow gold, it does not match certain skin tones well as yellow gold does.
White gold is made by mixing gold with different alloys. This mixture makes white gold stronger and more scratch-resistant, but because the rhodium often used to coat white gold loses its luster, it needs yearly re-plating to maintain its original color. White gold was mixed with nickel in previous times, but this can cause an allergic reaction in some people. While yellow gold is made of a softer gold alloy, it does not need re-plating to maintain its original color; a simple polishing suffices. Yellow gold is alloyed with zinc and copper, which produce fewer allergic reactions than the older white gold pieces with nickel alloy do.
White gold matches more outfits because it is a neutral color, but it does not complement darker skin tones as well as yellow gold does. While yellow gold looks better with darker skin tones, it can make fairer skin look washed out by comparison. White gold has the look of platinum or titanium, but without the added cost. Yellow gold is more symbolic of marriage and is the most popular metal used for wedding and engagement bands.