Copper
Pure copper or high-copper alloy
Warm reddish-orange, the distinctive salmon-red of pure copper. Oxidises to brown then eventually verdigris green
Composition
Pure copper (Cu); alloyed in brass (Cu-Zn) and bronze (Cu-Sn)
Physical properties
| Density | 8.96 g/cm³ | Weight per unit volume. Platinum is ~40% heavier than 18k gold at equal size |
|---|---|---|
| Melting range | 1085 °C | Working temperature for alloys. Pure metals have a sharp melting point |
| Vickers hardness | 35 HV | Higher HV = greater scratch resistance in service |
| Mohs hardness | 3 | Approximate equivalent for comparative reference |
| Tensile strength | 210 MPa | Resistance to breaking under tension, relevant for prongs and fine settings |
| Purity | 99.90% | Fine metal content by mass |
| Tarnish resistance | Poor | Surface oxidation / sulphidation under typical wear conditions |
| Workability | Excellent | Ease of forming, soldering, and fabricating under standard jewellery workshop conditions |
| Hypoallergenic | Allergy risk | Likelihood of triggering skin reactions under normal wear |
Common uses
Folk jewellery, craft jewellery, enamelling base, electroforming, wire wrapping, patinated art jewellery, health/magnetic bracelets
Hallmarking & identification
No precious metal hallmark. Sometimes stamped Cu. Primary use in jewellery is as a colouring alloy in gold (rose gold) and silver alloys, or as a standalone in craft and folk traditions.
Tarnishes rapidly on exposure to air and moisture. Patina is intentional in some styles; remove with commercial copper cleaner or lemon and salt paste if unwanted. Can leave green marks on skin, a harmless reaction between copper and skin acids.
Market & pricing
Among the cheapest metals used in any jewellery context. Priced as an industrial commodity.