One metal. Many colours. | Canvas of Knowledge

An alloy is a mixture of metals

Pure gold has a characteristic yellow appearance, but much gold jewellery is an alloy: gold mixed with other metals. Alloying changes practical properties and can also change colour. The World Gold Council describes this as a way to make malleable gold more durable while expanding its palette. The result is not a new element. It is a material whose behaviour and appearance reflect both its gold content and the particular metals sharing the mixture. [1]

Copper brings a warmer tone

Copper is important to the pinkish or reddish appearance associated with rose gold. Jewellery alloys may also include silver and other metals, so there is no single recipe behind every rose-coloured piece. GIA describes jewellers adjusting the blend to achieve a desired hue. The colour name therefore describes a family of appearances rather than a complete chemical specification. Two items described as rose gold can differ in both their precise shade and the proportion of gold they contain. [2]

White can involve two different layers

White gold is produced by combining gold with metals that make the alloy paler. Palladium is one example; different formulations use different combinations. A white-gold item may also have a rhodium coating that changes the appearance of its outer surface. GIA explains that this coating can wear over time, revealing the underlying alloy. The bulk material and the visible surface must therefore be distinguished. A bright white finish does not, by itself, identify the metal throughout the object. [1] [2]

Purity has its own language

Caratage or karatage describes gold’s share of an alloy, while millesimal fineness expresses that share in parts per thousand. These measures answer a different question from yellow, rose or white. An item’s specified fineness, appropriate marks and product description provide information that its colour cannot supply. A photograph adds further uncertainty because illumination and display settings alter appearance. The central distinction remains simple: changing the alloy or its surface can change what we see without colour becoming a reliable measure of gold content. [1] [2]

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Sources & further reading

Sources checked 14 November 2026. The artwork is illustrative. Reference organisations do not endorse this website. Financial examples are educational, not investment recommendations.