Last updated on January 29, 2021
Contrary to popular belief, there is no single level of gold purity used for all jewellery. There is a variety of different purity levels used for rings, bracelets, earrings and other fine jewellery in different countries. Each level of gold purity has its advantages and disadvantages which affect the hardness, durability and the price of a jewellery piece.
How Gold Purity is Measured
The purity of gold is measured using the karat system. This system has been developed to measure the ratio of pure gold to other metals or alloys in a piece of gold jewellery.
Although the term “karat” sounds similar to the term “carat”, these two measurements are completely different. Karat system is used to measure gold purity while carat is a unit of mass used to weigh diamonds and other gemstones. The measurement used to weigh gold is troy ounce (1 troy ounce = 31.1035 grams).
Karats, marked as “k”, “K” or “Kt”, are measured on a scale from 0 to 24, the latter being the purest form (pure gold) with no other metals. The higher the karatage, the purer the gold.
The minimum gold purity for an item to be called gold varies by country. For example, in the US the legal minimum standard gold purity is 10k. In the UK, France and Portugal the lowest permitted gold purity is 9k while in Greece and Denmark the minimum standard is 8k.
What is the Fineness of Gold?
Fineness is another way of measuring gold purity popular in the West which is expressed in parts per thousand.
In this system, pure gold which is 24k is expressed as 1000 parts out of 1000. For example, to calculate 24k gold fineness you need to divide 24k by 24k and multiply by 1000 which will give you a fineness of 1000. However, in practice, pure gold fineness is marked as 999.9 because there is likely to be a slight impurity in any gold. If you divide that number by 10, you will get the percentage value – 99.9% which indicates the pure gold content in a piece.
Following the same logic, 14k gold fineness should be marked as 583 (14/24 x 1000 = 583.333), but most manufacturers have adopted the European practice of making 14k gold slightly over 583, thus 14k gold fineness is marked as 585.
It is worth mentioning that accepted tolerances on gold purity vary from country to country. For example, in the US the permitted negative tolerance is 0.3%, while in China 1% is legally allowed.
Gold Purity Conversion Chart
|NUMBER OF KARATS||PARTS OF GOLD||% OF GOLD PURITY||FINENESS|
24k gold is pure gold. This means that all 24 parts in the gold are pure gold without traces of any other metals. It’s known to be 99.9% pure and has a bright yellow colour.
There is no higher form of gold than 24k. Since it is the purest form of gold, 24k is more expensive than other types of gold.
24k gold is softer and less durable compared to the gold of a lower karatage. Hence, it is not suitable for regular forms of jewellery such as engagement rings, earrings etc. However, gold of this purity level is widely used for coins and bars as well as electronics and medical devices.
22k gold consists of 22 parts of pure gold and 2 parts of other metals such as silver, zinc, nickel and other alloys.
This type of gold is commonly used in jewellery making the countries of Southeast Asia, the Middle East and well as in India.
22k gold a little harder and more durable than 24k gold due to mixed metals. However, you should be aware that although this type of gold is suitable for plain gold jewellery, it is not preferable for diamond and heavily studded jewellery as it is not durable enough for harder gemstones.
21k gold consists of 21 parts of pure gold and 3 parts of other metals or 87.5% of pure gold and 12.5% of other alloys.
This level of gold purity is popular for plain jewellery mainly. Although it is a little more durable than 22k gold, its hardness is still not enough for heavy gemstones.
21k gold is very popular in the countries of the Middle East such as Jordan, Lebanon, Egypt, Iran, Iraq, Syria, Israel, Saudi Arabia and others.
20k gold consists of 20 parts of pure gold and 4 parts of other metals, in other words, it is composed of 83.3% gold and 16.7% alloy.
This type of gold can be found in some vintage jewellery shops around Europe and the US. 20k gold is preferable for plain gold jewellery as it is quite soft for heavily studded jewellery pieces. However, 20k gold is quite popular in India, meaning purity standards vary from country to country.
18k gold contains 18 parts of pure gold and 6 parts of other metals added. It is 75% pure gold mixed with 25% of other metals like copper, silver etc. which make this type of gold less expensive than 24k, 22k, 21k and 20k gold.
Although 18k has a slightly dull gold colour compared to higher levels of purity, it still shows a bright gold colour.
Nowadays, diamond and other gemstone jewellery is usually made in 18k gold. It is the best choice for those who want to have the most amount of gold and still possess a high level of durability.
15k gold contains 15 parts of pure gold and 9 parts of other metals or alloys. It is 62.5% pure gold mixed with 37.5% other metals.
This type of gold was common during the Victorian era (1837 – 1901). In modern times 15k gold is hardly ever used for jewellery. Instead, 14k or 18k gold is the standard alternative for this level of purity. However, 15k gold jewellery can be found in some vintage jewellery shops around the world.
14k gold contains 58.3% pure gold and 41.7% other metals, or 14 parts of pure gold and 10 parts of other metals. 14k gold is quite durable and will not scratch that easily as other gold types with a higher purity level.
This is the most popular gold type for rings and other wearable jewellery in the US and the UK.
14k gold has a beautiful rich gold colour which is slightly less saturated and intense than 18k gold. 14k gold is the best choice for those looking for the perfect balance between durability, price and look.
The only disadvantage of 14k gold is its potential to trigger skin irritation if you are sensitive to such metals as copper, silver, nickel, zinc, iron etc.
12k gold contains 50% pure gold and 50% other metals. The high content of other alloys makes 12k gold very durable and suitable for everyday wear.
This type of gold is not widely available for wedding and engagement rings because of its hardness, but it is commonly used in plain gold necklaces and chains.
Be aware that jewellery pieces made in 12k gold can cause allergies as well.
The first thing you should know about 10k gold is that it contains more alloy (14 parts) than pure gold (10 parts). It contains 41.7% pure gold and 58.3% other metals.
10k gold is the most durable option between others and it makes the best choice for people looking for the cheapest price. Anything with a lower percentage of pure gold cannot be marketed and sold as gold in the United States.
Most top vendors don’t even offer 10k gold, as it’s hard and not suitable for diamond and other gemstone jewellery production.
9k gold consists of 9 parts of pure gold and 15 parts of other metals, or 37.5% pure gold and 62.5% other metals.
Depending on the country it is sold in, 9k gold is not always considered gold. For example, in the US 9k gold cannot be marketed as gold but in the UK, France and Portugal it is the lowest permitted gold purity.
Since 9k gold contains less pure gold than other metals it is quite cheap per gram. This type of gold is very durable, meaning it is hard to scratch. However, depending on the alloys used in 9k gold, sometimes it is softer than 18k gold, for example.
8k gold consists of 8 parts of pure gold and 16 parts of alloys, or 33.3% pure gold and 66.7% alloys.
This type of gold is not considered gold in the US due to its composition but in Greece and Danmark, 8k gold is still legally marketed and sold as gold.
This is an even cheaper option with more hardness and durability. However, it also may cause skin irritation in case you are allergic to zinc, nickel, copper etc.