Gold won't tarnish, rust, or corrode, and though it's very strong, it is also the most malleable of all metals.
Factors of Gold
Pure gold is too soft to withstand the stresses of everyday wear, so it is mixed with 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. For example, 18-karat gold is made up of 18 parts gold and 6 parts alloy.
The color of gold is determined by two factors: the type of metal alloys included in it and the percentage of each metal alloy.
Gold alloyed with silver and copper. It is the most frequently used type of gold there is.
Gold alloyed with a large percentage of silver, or a selection of other white metals.
Gold alloyed with copper, and perhaps silver. Usually the proportions are about one part of copper to three parts of 24-karat gold.
The price of gold jewelry is dependent upon the purity of the gold used or karat weight, as well as the design and construction of the piece of jewelry.