Fineness and carat

The measure of gold quality

 

 

Since late antiquity, the gold content of coins has been measured in the mass percentage of a coin that was accounted for by gold. The most valuable coin, the solidus, had a purity of almost 24 carats. The mass and value of a ceration was 1⁄24 of a solidus, so the number of ceratia of gold that made up the coin also determined its fineness.
Because of their traditional use, copper, silver and gold are also known as coinage metals.

Fineness

The fineness indicates the proportion of pure gold in an alloy and is usually given in per mille (‰). For example, a fineness of 750/1000 means that the alloy consists of 75 % pure gold and an additional 25 % alloying metals, such as silver, copper and palladium. The rest of the alloy consists of other metals that contribute to the hardness and colour of the alloy of our rings. In Europe, fineness specifications such as 585/1000 (equivalent to 14 carats) and 750/1000 (18 carats) are frequently used. In the countries of the former Soviet Union 583 alloy.

Carat (kt)

The carat (abbreviation kt or C) is a unit of measurement for the fineness of gold. The term is derived from the metric carat, which is also used as a unit of weight for gemstones, but stands for 0.2 g (1⁄5 gram) and is written Kt or ct.
Carat is a unit of measurement that indicates the degree of purity of gold and is also used for gold. One carat corresponds to 1/24 pure gold. Therefore, 24 carat corresponds to pure gold. In the jewellery industry, 24 carat (pure gold), 18 carat (75 % gold), 14 carat (58.5 % gold) and other carat values are often used to indicate the gold content in the alloy. Carat A denominations are particularly common in regions such as the USA.

Example

A piece of jewellery with a fineness of 750/1000 contains 75 % of pure gold and 25 % of other metals.
A piece of jewellery with a carat specification of 18 carats corresponds to a fineness of around 750/1000.
In practice, both specifications ultimately mean the same thing: the proportion of gold in the alloy. The choice between fineness and carat often depends on regional and traditional preferences as well as legal requirements. In Europe, fineness indications are more common, while in other regions carat indications are more common.

Typical precious metal alloys for gold

 

Fineness specification (‰)

Carat

Gold content in per cent

333 8 kt 33,3 %
375 9 kt 37,5 %
585 14 ct 58,5 %
750 18 ct 75 %
916 22 kt 91,6 %
999 24 ct 99,9 %

The remaining proportion is silver and copper, these two metals are added to an alloy in varying proportions, e.g. to increase the strength or determine the colour.

Why we do not use 333 gold

The designation "333 gold" refers to a gold alloy with a fineness of 33.3 %. This means that only one third of the alloy consists of pure gold, while the rest is made up of other metals such as silver, copper or zinc. This alloy is legally authorised in some countries and may be sold as "gold", even if the gold content is comparatively low.
Overall, 333 gold offers a cost-effective option for those looking to buy gold jewellery, but it is important to consider the potential drawbacks, especially when it comes to making rings that will be worn on a daily basis and subjected to more wear and tear.

 In Switzerland, 333 gold is recognised as gold-bearing metal and as Imitation labelled.