A karat, or carat, is a unit used to measure the purity and quality of gold. The higher the karat rating — of the purest possible being 24 karats — the less the gold has been mixed with other metals, such as silver or copper, to make a gold alloy. 24k gold is bright yellow, 99.9% to 100% pure gold that is not mixed with any other metal. Its purity makes it very soft and pliable — and therefore unsuitable for regular wear and use. To make gold more resilient, other metals are mixed with it during the manufacturing of jewelry and gold fixtures. 18k gold, for example, is 75% gold, with another 25% being of some other metal or mixture of metals. 18k gold is less expensive and more dully colored than pure gold.
|18k Gold||24k Gold|
|Percentage of gold||75%||99.9% - 100%|
|Also known as||750 gold||Pure gold or fine gold|
|Value||More expensive than 14k gold||More expensive than 18k gold or 22k gold; usually cheaper than platinum|
|Vividness of color||More vivid than 14k gold, duller than 24k||Has a distinct bright yellow color|
|Common Uses||Fine jewelry, electronics||Fine jewelry, as an investment, for decoration, in electronics, in medical devices/tools|
Difference in Appearance
24k gold is always a vivid, bright yellow. 18k gold comes in a wide range of colors, as it is an alloy, a metal mixed with other metals. Some common colored gold that is available in 18k purity includes rose gold (gold and copper) and white gold (usually nickel and gold).
Uses and Applications
Along with 14k gold and 10k gold, 18k gold is common in jewelry making. Though 18k gold jewelry is not as resistant to scratches and other marks as 14k gold (and under), 18k gold is often preferred over pure, 24k gold, which is both expensive to work with and prone to damage due to its softness.
Pure gold, while occasionally used for fine jewelry, is more commonly seen in investment items, such as gold coins, bars, and bullion. These gold items are minted, meaning they are manufactured in an industrial minting facility that produces gold or other metal coins, bars, and bullion. In the U.S., as in some other countries, how pure a certain item, such as a gold bar, must be is determined by legislation, which usually requires 99.9% purity.
Both 18k and 24k gold are used in decorative gilding processes, like gold leafing and plating. 22k gold and better is easier to work with when it comes to decoration because it is very easy to make it purer gold into thin sheets.
On occasion, 24k gold is used in electronics and medical devices. For example, children who suffer from frequent ear infections are sometimes fitted with gold tympanostomy tubes to improve aeration of the middle ear.
Gold's atomic structure makes the metal simultaneously dense ("heavy") and soft. Pure gold's softness makes it so malleable, in fact, that it is possible to hammer one ounce of pure gold down into a very thin, 300 foot square sheet for gilding.
18k gold, being mixed with other metals, is harder and stronger than pure, 24k gold, but its 75% gold content still makes it more susceptible to damage than 14k gold. Overall, care for both types of gold is relatively easy, but 24k gold jewelry should not be worn every day. Both can be tarnished when exposed to bleach, 24k gold especially.
The price of gold jewelry varies by design, craftsmanship and the alloys used, but as 24k contains more gold than 18k, it is usually more expensive.
The value of 18k gold can be calculated by multiplying its pennyweight by .750, dividing the current spot gold price by the number of pennyweights per ounce, and then multiplying the two values together.
The value of 24k gold is calculated by dividing the current spot gold price by the number of pennyweights per ounce, and then multiplying this value to the pennyweight of the product.
While gold has historically been cheaper than platinum, prices for pure gold rose above the price for pure platinum in late 2011.
Gold is bought for a wide variety of reasons. It is common for people to invest in gold during recessions or at other times to hedge against inflation. During good economic times, gold jewelry's popularity grows.
As 24k gold is 99.9-100% gold, it is also referred to as pure gold or fine gold. 18k gold can be referred to as 750 gold.