Different types of gold

The various types of gold are categorised by colour and karat. The colour of gold denotes the type of metal used in the alloy.

The karat describes the amount of gold used in relation to other metals.

Aside from its dazzling beauty, gold is a noble metal. This means it is highly resistant to corrosion or tarnishing.

Contrary to popular belief, when you buy a piece of gold jewelry, it usually isn’t made out of pure gold. Instead, almost all gold jewelry is made from an alloy created by combining pure gold with a variety of other metals.

The reason for this is that pure gold is very soft. If rings, earrings and other jewelry were made using pure gold, they’d scratch, scuff, dent and warp extremely easy, often just from brushing against another surface. The greater the proportion of other metals in a gold alloy the stronger it becomes, but at the same time the less resistant to corrosion or tarnishing it becomes.

KaraT

Because of this, modern gold jewelry uses gold that’s mixed with other metals. The purity of this gold used to be measured using the karat system, which provides information on what percentage of any type of gold is made up of pure gold.

Gold karatage is expressed in parts out of 24. For example, pure gold is 24K, as all 24 out of 24 parts consist of pure gold. 

Karat defines the proportion of gold to other metals in an alloy.

But as 24 karat gold being too soft to make jewelry, it is mixed with other metals to "harden" it.

18 karat gold means that of the 24g of alloy, 18g is "pure gold" which is 75.01%. It is also called 750/1000 gold.

Due to European laws, the gold content can no longer be expressed with the karat system, but appropriate marking is required:

this means that the gold content needs to be marked in parts of 1000 (=24 karat) The marking “750” means that 750 out of 1000 parts of that item are made of pure gold. In short, it’s 75% pure gold which can be called high-graded solid gold.

Colours of 18 karat gold

The type of metal used in a gold alloy leads to variations in its colour. The colour also becomes stronger with greater proportions of other metals.

White metals, such as silver, platinum and palladium, lead to whiter alloys. Copper gives a red tint.