When looking for jewelry for a loved one, an important difference is the type of metal. Much of this decision comes down to the aesthetic value. For example, a woman who has mostly gold jewelry will not want a silver piece, as it is hard to match this with what she usually wears.
While the difference between gold and silver is generally very distinct, this is not the case between white gold and silver.
Gold varies substantially in it's purity. For example, 18k gold is 75% pure gold, while 14k is 50% pure gold and 10k is around 41.7% pure gold. The remainder of the item is made of a combination of other metals. These act to reinforce the gold, making it sturdy and durable enough to be worked with. The choice of metal has a strong influence over the color of the final product. Yellow gold involves alloying the gold with metals such as zinc and copper, while white gold is made using white metals as the basis for the alloy, such as palladium or silver. Because it is an alloy, the color does not flake or wear off. The color of the gold does not affect the percentage of pure gold that is present; a 10k white gold ring has the same percentage of gold in it that a 10k yellow gold ring does. A white metal called rhodium is sometimes used to coat white gold rings to make them appear whiter, as white gold is naturally light grey.