Gold

Gold won't tarnish, rust, or corrode, and though it's very strong, it is also the most malleable of all metals.

Pure gold is too soft to withstand the stresses of every-day wear, so it is alloyed with a mixture of metals like silver, copper, nickel, and zinc to give it strength and durability. Karatage, noted by a number followed by "k" indicates purity, or how much of the metal in a piece of jewelry is gold. Karatage is expressed in 24ths, making 24k gold 100% gold.

The color of gold is determined by two factors:

The type of metal alloys included in it

The percentage of each metal alloy

Yellow Gold
In jewelry at Blue Nile, you'll find 18k and 14k yellow gold. 18k gold contains more precious metal than 14k gold. It is composed of 75% gold, which is alloyed with other metals to make it strong enough to withstand every-day wear. Because 14k gold is composed of only 58.3% gold, and 41.7% other metals that give it strength, its gold color is not as rich as 18k gold. 14k gold is most commonly found in cases where strength is most important, like in earring backs and bracelet clasps.