Gold was one of the first known metals. It was the foundation of many kingdoms. It defined our currency system since money represented a value in gold. It has been the most important of metals. Gold will not tarnish, rust or corrode. It is also the most malleable of metals.
Gold in its purest state (24karat) is too soft to withstand the stresses of everyday wear so it is never used to make jewelry. However, once alloyed with a mixture of other metals like silver, copper, nickel or zinc, it becomes strong and durable. Karatage, noted by a number followed by "k" indicates purity, or how much of the metal in a piece of jewelry is gold.
24 karat = 100% gold Too soft for jewelry
22 karat = 91.7% gold Very soft — not recommended for jewelry
18 karat = 75.0% gold Recommended for fine jewelry
14 karat = 58.3% gold Recommended for jewelry
12 karat = 50.0% gold Not acceptable for jewelry
10 karat = 41.7% gold The legal karat limit considered as real gold in the United States
The color of gold is determined by 2 factors. One is the type of metal it is alloyed to and the other is the percentage of each metal alloy. For example 18k gold will have a richer gold color than 14k gold since 18k contains a higher percentage of real gold.
In the case of white gold, the gold is alloyed with rhodium which is a shiny, white metal that is extremely hard. Rhodium makes the gold white in color so you have white gold. Depending on the amount of wear, over time this rhodium plating may wear off, revealing the original metal color. Re-plating is a simple process that can be done to restore your jewelry's whiteness if needed. The same is true for rose gold. The gold is alloyed with copper which creates a rose colored gold.
The price of gold fluctuates everyday with the market. Pricing the individual piece of jewelry depends on the percentage of real gold used (its karat weight) as well as the design of the piece and its construction.
To take the best care of your gold jewelry, keep it away from harsh chemicals like chlorine and cleaning fluids. If you need to clean your gold jewelry, use a solution of warm water and detergent-free soap, washing it gently with a soft-bristled brush (or toothbrush). Store your gold jewelry in soft cloth bags or their original boxes to protect them from the exposure to harsh daily elements.