Gold Plating
Also: gold coating, gold-plated finish, gold-plated
Gold plating is the deposition of a very thin layer of gold onto a base or precious metal, glass or ceramic substrate to improve appearance, corrosion resistance or electrical performance.
A gold-plated item is not a solid piece of gold but a layered composite: a base substrate — commonly brass, copper, sterling silver or stainless steel — is covered with a wafer-thin coating of gold. The finished object looks like gold yet contains only a fraction of the precious metal. If you want to know the true material value of a plated piece, reach for the melt-value calculator: with thin coatings the amount of gold present is effectively negligible.
The main processes at a glance
| Process | Layer thickness | Typical application |
|---|---|---|
| Electroplating | 0.1 – 10 µm | Jewellery, electronics, medical devices |
| Fire gilding (amalgam) | 1 – 30 µm | Historic sacred art, restoration |
| Mechanical gilding (rolled gold / gold-filled) | 10 – 100 µm | Watch cases, premium accessories |
| PVD gold coating (vapour deposition) | 0.1 – 1 µm | Watches, design objects |
| Gold leaf | 0.1 – 0.5 µm | Architecture, book art, catering |
Electroplating is by far the most widely used method today. The workpiece is made the cathode in a gold-bearing electrolyte bath, and a direct current causes gold ions to settle on its surface. The thickness can be dialled in precisely and, for costume jewellery, is often just 0.5 µm — far too little to matter when a value is being worked out.
Historic fire gilding blended gold with mercury into an amalgam that was brushed on and then heated; the mercury boiled off and left the gold behind. Because of the toxic fumes this technique is now banned and only permitted for restoration work under strict protective controls.
Gold plating versus related terms
- Vermeil: gold plating on sterling silver (≥ 925) with at least 2.5 µm of gold; a legally protected term in France and the United States.
- Gold-filled / gold double: a mechanically rolled gold layer (≥ 10 µm), tougher and longer-lasting than an electroplated coat.
- Rhodium plating: the same principle but using rhodium instead of gold, common on white-gold jewellery to brighten the surface.
Marking and the legal position
Within the EU a plated article may not be described simply as "gold". Permitted wording includes "gold-plated" or a statement of the layer thickness in micrometres. Where a fineness hallmark is absent, the message is clear: this is not a solid precious-metal product. Buyers value plating accordingly when purchasing scrap, and the purchase-price calculator shows why: the actual gold content of a 10 g electroplated piece with a 1 µm coat is typically less than 5 mg.
Durability and care
Longevity depends heavily on the coating thickness and the base metal:
- Thin electroplated layers (< 1 µm) wear through at contact points within months.
- Vermeil and gold-filled items last several years to decades if cared for.
- Acids, perspiration, chlorine and mechanical stress all speed up wear.
- Re-plating is possible provided the underlying piece is undamaged.
For collectors and investors the rule is simple: gold-plated coins or bars hold no greater gold value than the base object — the gold deposited is minute. The coin authenticity check can help tell a solid gold coin from a plated replica.
In brief
Gold plating is a surface finish, not a gold product — the precious-metal content is vanishingly small and has almost no bearing on the material value. Anyone who wants genuine gold content should look for a fineness hallmark and buy investment gold of verified quality.