When it comes to gold, purity is key. But first, you need to understand how gold purity is represented to get an accurate evaluation of an item. Most of the time, gold items will have a purity hallmark or some other form of indication to state their purity.
The purity of an item is a crucial piece of information, especially when it comes to jewellery. Pure gold is incredibly soft and malleable. Manufacturers often mix or alloy pure gold with other base metals to make it more durable. Therefore, it is easier to value a gold article if you know its purity.
There are two systems used to measure gold purity: carat (ct) (Karat (kt) in the US) and the fineness system. Both carat and fineness show how much pure gold to other base metals is in a piece of jewellery or other products.
Gold Carat – System
Carat is a unit of measurement for the purity of gold. Carat indicates how much pure gold is within a piece of an item to other metals in parts of 24. On the gold purity scale, 24 carats is pure gold. The lower the number, the less pure the gold is.
24 carat – equal to 100% pure gold
Pure gold that contains no other metals. This is the highest purity of gold that you can find.
22 Carat Gold – equal to 22/24 pure gold
Contains 22 parts pure gold and 2 parts other metals.
18 Carat Gold – equal to 18/24 pure gold
Contains 18 parts pure gold and 6 parts other metals.
14 Carat Gold – equal to 14/24 pure gold
Contains 14 parts gold and 10 parts other metals.
9 Carat Gold – equal to 9/24 pure gold
Contains 9 parts pure gold and 15 parts other metals. This type of gold is still considered real gold but is not as pure as 18 or 24 carat gold.
Gold Fineness – System – What is 999.9 Gold in Karat?
Millesimal fineness is another way of expressing purity, but it uses a different system to carat. With fineness, purity is measured in parts per thousand (1000) rather than 24. This system is more accurate and simpler to use. In the fineness system, 999.9 is pure gold, equivalent to 24 carats.
24 carat – equal to 999.9 (99.9%) pure gold
22 carat – equal to 916/1000 (91.6%) pure gold
18 Carat Gold – equal to 750/1000 (75%) pure gold
14 Carat Gold – equal to 585/1000 (58.5%) pure gold
9 Carat Gold – equal to 375/1000 (37.5%) pure gold
The UK has specific requirements for hallmarking gold items for sale, except for coins and pure gold bars. According to the law in the UK, any gold product weighing more than 1g or 0.0321507 troy ounces must be hallmarked with the item’s Millesimal fineness.
For example, Millesimal fineness is usually rounded to the nearest three figures. For example, if an item is 18 carat gold, it would be hallmarked as 750.
How many Carats is Pure Gold?
The worldwide standard for gold purity is 24 carats or 999.9 fineness. However, creating 100% pure gold is impossible because refining makes tiny particles increasingly difficult and costly to remove. Thus, the highest possible purity for gold is (three nines fine) 999 or 999.9 rather than 1,000 fineness.
In 1957, Australia’s Perth Mint created the purest gold ever. This was 999.999 fineness and is now referred to as ‘six nines fineness’. The Royal Mint uses it as its standard for purity.
Gold investment bars must have a purity of at least 995 fineness. The London Bullion Market Association is responsible for testing gold and creating a ‘Good Delivery List’ that outlines the standards for gold investment bars, including the required fineness.
Minimum Purity of Gold
Pure gold is mainly used in investment gold bullion bars and coins. When jewellers refer to it, they call it gold alloy because it’s mixed with other metals. However, for an item to be considered gold, it must meet a particular purity level.
Every country has its own limits for the minimum purity level. For example, the legal carat minimum in the US is 10 or 417 fineness. However, in France, the UK, Austria, Portugal and Ireland – gold cannot be sold as such if it is below 9 carat or 375 fineness. The percentage of carats in Denmark, Germany and Greece is lower, at 8 carat or 333 fineness.