Gold Plating
Also: Gold layer, Gold coating, gold-plated
Gold plating refers to the application of a thin layer of gold onto a substrate of base or precious metal, glass or ceramic in order to improve appearance, corrosion protection or electrical properties.
Gold plating is not a solid piece of gold but a layered composite: onto a substrate material – often brass, copper, sterling silver or stainless steel – a wafer-thin layer of gold is applied. The result looks like gold but contains only a fraction of the precious metal. Anyone wishing to know the actual material value of a gold-plated piece should use the melt value calculator – because with thin coatings the gold content is practically negligible.
Processes at a Glance
| Process | Layer thickness | Typical application |
|---|---|---|
| Electroplating | 0.1 – 10 µm | Jewellery, electronics, medical technology |
| Fire gilding (amalgam) | 1 – 30 µm | Historical sacred art, restoration |
| Mechanical gilding (rolled gold / doublet) | 10 – 100 µm | Watch cases, high-quality accessories |
| PVD gilding (vapour deposition) | 0.1 – 1 µm | Watches, design objects |
| Gold-leaf application | 0.1 – 0.5 µm | Architecture, book art, gastronomy |
Electroplating is today the most widely used process: the workpiece is immersed as a cathode in a gold-bearing electrolyte bath; direct current deposits gold ions onto the surface. The layer thickness can be precisely controlled and, for costume jewellery, is often only 0.5 µm – too little to carry any weight in a price valuation.
Historical fire gilding mixed gold with mercury to form an amalgam, which was applied and then heated; the mercury evaporated, the gold remained adhered. This process is banned today because of its toxicity and is only permissible in restoration under strict protective measures.
Gold Plating vs. 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 USA.
- Doublet / gold doublet: Mechanically rolled-on gold layer (≥ 10 µm), firmer and more durable than electroplated coatings.
- Rhodium plating: Analogous process using rhodium instead of gold, common on white-gold jewellery for brightening.
Marking and Legal Position
In the EU, gold-plated products may not be described as "gold". Permissible descriptions are "gold-plated" or the layer thickness in micrometres. If a fineness hallmark is missing, it is clear: this is not a solid precious metal product. Buyers value gold plating accordingly low in scrap-gold purchasing – the purchase price calculator shows why: the actual gold content of an electroplated 10 g piece of jewellery with a 1 µm layer typically amounts to less than 5 mg of gold.
Durability and Care
Durability depends strongly on the layer thickness and the substrate metal:
- Thin electroplated coatings (< 1 µm) wear through at contact points within months.
- Vermeil and doublet last several years to decades with careful handling.
- Acids, sweat, chlorine and mechanical stress accelerate wear.
- Re-plating is possible if the substrate piece is undamaged.
For collectors and investors: gold-plated coins or bars have no higher gold value than the base coin – the amount of gold applied is minimal. The coin authenticity check can help distinguish between solid gold coins and gold-plated copies.
In Brief
Gold plating is a surface finish, not a gold product – the precious metal content is vanishingly small and has hardly any influence on the material value. Anyone who values genuine gold content watches for the fineness hallmark and buys investment gold of verified quality.