✦ Metallurgy & CraftUpdated: September 2, 2026
Gold Color Metallurgy: Phase Diagrams, Copper/Silver/Palladium Ratios & Tarnish Resistance
Authored by Italian Goldsmithing & Metallurgical Review Board
The chemical formulation of precious gold alloys: ternary phase diagrams (Au-Ag-Cu), nickel-free white gold, and stabilizing rose gold against oxidation.
Pure 24-karat gold is chemically inert but too soft for complex stone-set jewelry. Goldsmiths alloy gold with silver, copper, and palladium to manipulate color and hardness.
1. 18K Gold Alloy Color Formulations
| 18K Gold Color | Gold (Au %) | Silver (Ag %) | Copper (Cu %) | Palladium / Zinc (%) |
|---|
| Yellow Gold (Standard 3N) | 75.0% | 12.5% | 12.5% | — |
| Rose / Pink Gold (4N) | 75.0% | 9.0% | 16.0% | — |
| Red Gold (5N) | 75.0% | 4.5% | 20.5% | — |
| Green Gold (Electrum) | 75.0% | 25.0% | — | — |
| Palladium White Gold | 75.0% | 5.0% | 5.0% | 15.0% Palladium |
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Italian Goldsmithing & Metallurgical Review Board
Our technical panel oversees Italian alloy standards (D.Lgs. 251/1999), 18K solid gold tensile durability, Florentine hand engraving, and Responsible Jewellery Council (RJC) supply chains.
Planning a Bespoke 18K Gold Commission?
Consult our master goldsmiths for CAD modeling, stone allocation, and Florentine texture finishes.