Alloy
Also: Metal alloy, Alloying metal
An alloy is a mixture of a primary metal and one or more additional metals (alloying metals), resulting in deliberately altered physical or chemical properties.
An alloy is formed when at least two metallic elements are melted together. In the precious metals sector, the base metal — gold, silver, platinum or palladium — is always the primary constituent; the alloying metals determine colour, hardness, workability and corrosion resistance. The fineness indicates what proportion of the total weight is pure precious metal — expressed in thousandths (per mille) or karats.
Why is precious metal alloyed?
Pure gold (999.9 ‰) is very soft and barely suitable for jewellery. Alloying makes it possible to:
- Increase hardness and wear resistance (important for rings and bracelets)
- Control colour deliberately – copper yields rose gold, palladium or nickel yields white gold
- Adjust the melting point (relevant for foundry processing)
- Reduce costs – a lower precious metal content reduces the material value
Overview of typical gold alloys
| Name | Fineness | Karat | Typical alloying metals |
|---|---|---|---|
| Fine gold | 999 ‰ | 24 ct | – |
| 916 gold | 916 ‰ | 22 ct | Copper |
| 750 gold | 750 ‰ | 18 ct | Cu, Ag, Pd, Ni |
| 585 gold | 585 ‰ | 14 ct | Cu, Ag, Zn |
| 375 gold | 375 ‰ | 9 ct | Cu, Ag, Zn |
| 333 gold | 333 ‰ | 8 ct | Cu, Ag, Zn |
Silver alloys
Silver too is almost always alloyed. The best-known example is sterling silver with 925 ‰ silver and 75 ‰ copper — a standard that has applied to coins and cutlery since the Middle Ages. Other common fineness values:
- 835 silver – classic cutlery silver in Germany
- 800 silver – common in older coin and table silver
- 958 silver (Britannia) – high-purity silver, primarily for British coins
Calculating material value
The melt value of an alloy derives from the fine weight:
Fine weight = Gross weight × (Fineness ÷ 1000)
Melt value = Fine weight × current spot price per gram
The Melt Value Calculator can be used to quickly determine this value for gold, silver and other metals. The Gold Calculator automatically takes the entered fineness into account.
White gold – a special group
White gold is a gold alloy that acquires a silvery colour through the addition of palladium or nickel. Because the yellow tint often still shows through, white gold pieces are frequently rhodium-plated — coated with a thin layer of rhodium that provides the characteristic high shine. This layer is subject to wear and must be renewed occasionally.
Identifying and testing alloys
The fineness hallmark (punch mark) on jewellery indicates the composition. In Germany and the EU, the figure is customarily given in thousandths (e.g. "585" for 14-karat gold). X-ray fluorescence analysis (XRF) enables non-destructive, precise determination of the alloy composition — important when purchasing scrap gold.
Key takeaway
Alloys make precious metals practically usable: they control colour, hardness and workability, while fineness definitively establishes the true precious metal content — and thus the intrinsic value. When buying or selling jewellery and bars, it is always worth examining the hallmarks and per-mille figure.