Pure gold is slightly reddish-yellow in colour, but gold of various other colours can be produced by alloying gold with other elements.

There are many different colours of gold, each with its own unique history (from white to completely black). Some colours of gold are found in nature, while others can only be created artificially. All coloured gold gets its hue from another metal.

Coloured gold is divided into three groups:

Alloys with silver and copper in varying proportions to produce white, yellow, green and red gold. These are generally malleable alloys.

Intermetallic compounds, which produce blue and purple gold, as well as gold of other colours. They are generally brittle but can be used as gems and inlays.

Surface treatments such as oxide layers.

Red and rose gold 

Rose gold is an alloy of gold and copper, closely related to red gold in that it differs in the ratio of gold to copper and in whether or not silver is added. Rose gold is available in four grades:

18K (K-carat) rose gold (75 % gold, 22,25 % copper, 2,75 % silver)

18K rose gold (75% gold, 20% copper, 5% silver)

18K red gold (75% gold, 25% silver)

12K red gold (50% gold, 50% copper).

The addition of copper in the alloy with gold produces colours ranging from darker shades of yellow to intense red. In addition, up to 15 % zinc can be added to copper-rich alloys to change their colour to reddish yellow or dark yellow.

Rose gold is also not hypoallergenic due to its copper content, so make sure that whoever you buy it for is not bothered by copper jewellery - rose gold may be romantic, but skin rashes are not.

White gold

The gold market keeps up with the trends, and one of the most fashionable gold grades in recent times is white gold. White gold is an alloy of gold and a white metal such as silver, platinum, palladium or nickel. In general, an alloy of gold with any other metal (except copper) is sufficient to produce a lighter coloured gold. The usual formula for white gold consists of 90 % by weight of gold and 10 % by weight of nickel. Copper may be added to increase ductility.  Gold-palladium-silver and gold-nickel-copper-zinc alloys are used in the jewellery industry. Palladium and nickel act as primary brighteners for gold; zinc acts as a secondary brightener to weaken the colour of copper.

The nickel used in some white gold alloys can cause an allergic reaction when worn for long periods of time (including, in particular, in the cases of some wristwatches). This reaction, usually a minor skin rash due to nickel dermatitis, affects about one in eight people; for this reason, many countries do not use nickel in their white gold products. As a result, white gold products with a palladium impurity are placed on the market instead. However, this metal is more expensive and more difficult to process, which significantly increases the price of the product. White gold may also be plated with rhodium, palladium or platinum if the alloy does not give a satisfactory colour. Finally, however, it is worth noting that, in addition to the change in colour, different types of gold have different physical properties. Pure gold is a rather soft and fragile metal and therefore not very practical. The addition of other, harder metals makes gold harder and better suited as a material for making, for example, wedding rings or other jewellery.

Yellow gold

When we talk about yellow gold, many people immediately think of pure gold. However, yellow gold can actually come in a variety of carats, and therefore a variety of prices. 18 carat is the standard for the highest quality jewellery, and is usually made up of an alloy of gold, copper and silver.

Yellow gold is available in two grades:

18K yellow gold: 75% gold, 12.5% copper, 12.5% silver

18K yellow (darker) gold: 75% gold, 15% copper, 10% silver

Blue gold

Blue gold is a relatively new phenomenon that is still in its infancy. True blue gold is an alloy of gold and gallium or indium, giving it a greyish colour. The purity of this metal is usually around 11 K and it is relatively durable and inexpensive.

Oxide layers can also be used to extract blue gold: an alloy of 75 % gold, 24,4 % iron and 0,6 % nickel is heat treated at 450-600 °C.

Rich sapphire blue 20-23K gold can also be obtained by alloying with ruthenium, rhodium and three other elements and by heat treatment at 1800 °C; a coloured surface oxide layer 3-6 micrometres thick is formed.

Green gold

Green gold comes in 18K (75% gold) and 14K (58.5% gold) and varies in hue due to the amount of gold, silver, copper, zinc, cadmium and nickel used in its production. 18K versions are usually more valuable than 14K versions.

Cadmium can also be added to gold bullion to create a green colour, but its use raises health concerns as cadmium is highly toxic. An alloy of 75% gold, 15% silver, 6% copper and 4% cadmium produces a dark green alloy. Green gold is an ancient and somewhat mysterious metal, and is now almost unused.

Purple-purple gold

Purple gold (also known as amethyst gold and violet gold) is an alloy of gold and aluminium that is very rarely used for jewellery. This is because the addition of aluminium makes the gold brittle and can cause the metal to shatter on impact. Purple gold is more brittle than other gold alloys (it is an intermetallic compound, not a plastic alloy, and it can shatter from a sharp blow), so it is usually worked and faceted for use as a 'gemstone' in conventional jewellery, rather than as a jewel in itself.

For this reason, despite its high carat content (typically 88% gold), it is rarely used.

Grey gold

Grey gold is a type of white gold: an alloy of gold and palladium. It is very soft and is therefore used to set precious stones in jewellery, rather than as a material from which to make jewellery.

Black gold

Black gold can be produced in three different ways: oxidation, chemical vapour deposition and patination. All of these processes are complex and all are plating techniques. Therefore, black gold does not really exist in the same way as rose gold and white gold, which are alloys of real substances.

Copper-rich alloys can be treated with potassium sulphide to produce a range of colours from brown to black.

While the novelty may be exciting, the coating will definitely wear off over time, i.e. after about a year you will have a white gold ring.

Here are some of the most common questions and answers about the colour of gold.

Which gold colour is the most expensive?

It's not the colour that matters, but the purity. The purer the bullion, the higher its value. 

However, while a more valuable metal may look attractive, gold of lower purity is often more durable.

What is the rarest type of gold?

With the advent of modern smelting techniques, most colours of gold can be produced artificially, but pure, 24-carat gold is still the rarest.

What is the most common gold colour?

Yellow and white gold are the most common gold colours.

Which is the best colour for gold?

This depends on personal preference and desired use: which one goes well with your other jewellery? Which suits your outfit? Which is the prettiest? Which are you not allergic to? 

The choice is always up to you!