Alloy
Also: Metal alloy, Alloying metal
An alloy is a mixture of a main metal and one or more additional metals (alloying metals) that deliberately possesses altered physical or chemical properties.
An alloy is created when at least two metallic elements are fused together. In the precious-metals field the base metal — gold, silver, platinum or palladium — is always the main component; the added metals determine colour, hardness, workability and corrosion resistance. The fineness states what proportion of the total weight is the pure precious metal — expressed in thousandths (per mille) or in carats.
Why is precious metal alloyed?
Pure gold (999.9 ‰) is very soft and barely suited to jewellery. Alloying allows you to:
- Increase hardness and abrasion resistance (important for rings and bracelets)
- Control colour deliberately — copper yields red gold, palladium or nickel yields white gold
- Adjust the melting point (relevant for foundry processing)
- Reduce cost — a lower precious-metal share lowers the material value
Typical gold alloys at a glance
| Designation | Fineness | Carat | Typical additional metals |
|---|---|---|---|
| Fine gold | 999 ‰ | 24 kt | – |
| 916 gold | 916 ‰ | 22 kt | Copper |
| 750 gold | 750 ‰ | 18 kt | Cu, Ag, Pd, Ni |
| 585 gold | 585 ‰ | 14 kt | Cu, Ag, Zn |
| 375 gold | 375 ‰ | 9 kt | Cu, Ag, Zn |
| 333 gold | 333 ‰ | 8 kt | 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 used for coins and cutlery since the Middle Ages. Other common finenesses:
- 835 silver — traditional cutlery silver on the Continent
- 800 silver — often found in older coin and table silver
- 958 silver (Britannia) — high-purity silver, chiefly for British coins
Calculating the material value
The melt value of an alloy follows from the fine weight:
Fine weight = gross weight × (fineness ÷ 1000)
Melt value = fine weight × current spot price per gram
With the melt value calculator you can determine this figure quickly for gold, silver and other metals. The gold calculator automatically accounts for the fineness you enter.
White gold — a special group
White gold is a gold alloy that takes on a silvery colour through the addition of palladium or nickel. Because the yellow tone 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 wears down and must occasionally be renewed.
Recognising and testing alloys
The fineness hallmark on jewellery indicates the composition. Across the EU the figure is customarily given in thousandths (for example "585" for 14-carat gold). X-ray fluorescence analysis (XRF) enables a non-destructive, precise determination of the alloy composition — important when buying scrap gold.
In brief
Alloys are what make precious metals genuinely practical: they control colour, hardness and workability, while the fineness authoritatively fixes the true precious-metal share — and thus the substance value. When buying or selling jewellery and bars, it always pays to check the hallmark and per-mille figure.