Gold alloys
18k Rose Gold
18 karats, 750‰
Warm pink-gold. Characteristic rosy colour produced by the copper content; deepens slightly with age as copper oxidises
Composition
75% gold, ~22.5% copper, ~2.5% silver; the high copper content creates the pink hue
Physical properties
| Density | 15.20 g/cm³ | Weight per unit volume. Platinum is ~40% heavier than 18k gold at equal size |
|---|---|---|
| Melting range | 885–970 °C | Working temperature for alloys. Pure metals have a sharp melting point |
| Vickers hardness | 170 HV | Higher HV = greater scratch resistance in service |
| Mohs hardness | 3 | Approximate equivalent for comparative reference |
| Tensile strength | 540 MPa | Resistance to breaking under tension, relevant for prongs and fine settings |
| Purity | 75.00% | Fine metal content by mass |
| Tarnish resistance | Very good | Surface oxidation / sulphidation under typical wear conditions |
| Workability | Excellent | Ease of forming, soldering, and fabricating under standard jewellery workshop conditions |
| Hypoallergenic | Partial risk | Likelihood of triggering skin reactions under normal wear |
Common uses
Contemporary rings, bracelets, watches, couples jewellery, vintage-inspired pieces
Hallmarking & identification
Same 750 hallmark as all 18k gold. Colour cannot be hallmarked, only purity. Vintage pieces may show more copper oxidation.
Care & maintenance
Clean with mild soapy water. Copper content means slight surface darkening over time in some conditions; this is normal and can be removed by a jeweller. Very sensitive individuals may react to copper traces.
Market & pricing
Same purity as 18k yellow and white gold; slight premium or discount depending on market and copper content.