Gold
Gold as a material
Gold is used in jewellery, coins, medals and decorative arts. Pure gold is soft and malleable; alloying it with other metals affects hardness, colour and working properties.
Fineness and carat
Fineness states the parts by weight of gold per 1,000 parts of alloy. 585 gold means 58.5% gold, while 750 means 75%.
Gold carat expresses the gold share out of 24 parts. 18K corresponds to 750; 14K commonly corresponds to 585, although 14/24 is mathematically about 58.3%.
Colour and surface
Alloys produce yellow, white or red/rose gold. Copper contributes red tones; white gold can contain nickel or palladium and have rhodium plating. Colour alone does not establish fineness.
Gold can be beaten into leaf or applied as plating over other metals. A gilded object therefore does not necessarily consist of gold alloy throughout.
A historical object and its techniques
The Met holds a pair of Etruscan earrings, museum numbers 95.15.152 and .153, dated to the fourth or early third century BC. Their grape-cluster shapes combine repoussé decoration and granulation attached to a plate. The object brings several working techniques together. When dating other jewellery, such techniques must be considered alongside provenance and documentation.
Marks and identification
A fineness mark describes gold content. A responsibility mark identifies the party responsible for ensuring that the stated fineness is correct.
A mark alone does not establish designer, workshop and age. Compare marks with the object's construction and reliable catalogue or archival records. Marking practices need to be interpreted in the context of country and period, rather than applying one modern marking system to every older object.
Testing must also account for surface coatings. In 2025, GIA documented gold alloys plated with gold of higher fineness. The coating could produce misleadingly high results in X-ray fluorescence analysis, XRF. Results therefore need to be interpreted alongside microscopic examination of wear and plating. This requires professional analysis, rather than filing into jewellery at home.
Weight, documentation and assessment
Distinguish the net weight of the gold alloy from stones, pearls, springs, steel and other components. As a calculation example, 10 grams of homogeneous 585 alloy contain 5.85 grams of gold. This does not establish the gold weight of a composite jewel or its selling price.
Also document the designer, maker, age, any gemstones, ownership history and condition. Metal content and cultural-historical identification are different aspects of assessment. Read about object types, stones and remodelling in Jewellery.
