9k White Gold
9 karats, 375‰
Very pale silver-white with a slight yellow cast; rhodium plating required to achieve a true white appearance in most alloys
Composition
37.5% gold + nickel, copper, zinc (standard) or palladium blend; white metals dominate the alloy
Physical properties
| Density | 10.50 g/cm³ | Weight per unit volume. Platinum is ~40% heavier than 18k gold at equal size |
|---|---|---|
| Melting range | 850–900 °C | Working temperature for alloys. Pure metals have a sharp melting point |
| Vickers hardness | 200 HV | Higher HV = greater scratch resistance in service |
| Mohs hardness | 3.5 | Approximate equivalent for comparative reference |
| Tensile strength | 480 MPa | Resistance to breaking under tension, relevant for prongs and fine settings |
| Purity | 37.50% | Fine metal content by mass |
| Tarnish resistance | Good | Surface oxidation / sulphidation under typical wear conditions |
| Workability | Good | Ease of forming, soldering, and fabricating under standard jewellery workshop conditions |
| Hypoallergenic | Allergy risk | Likelihood of triggering skin reactions under normal wear |
Common uses
Affordable white metal jewellery, UK and Australian fashion jewellery, budget engagement rings, everyday pieces
Hallmarking & identification
Stamped 375 in most markets; 9K or 9ct in the UK and Australia. Typically nickel-containing; nickel allergy risk is higher than in higher-karat gold. Rhodium plating is almost always applied to mask the yellow cast.
Rhodium plating wears through faster than on 18k due to softer base. Avoid harsh chemicals and abrasives. Replating every 1–2 years restores white appearance.
Market & pricing
Most affordable white metal fine jewellery option. Popular in the UK and Australian mass market. Significant discount to 18k white gold at equivalent weight.