Gold Plating
Also: gold coating, gold-plated, gilding
Gold plating is the application of a thin layer of gold onto a base or precious metal, glass or ceramic to improve appearance, corrosion resistance or electrical properties.
Gold plating is not a solid piece of gold, but a layered composite: a wafer-thin layer of gold is applied to a base material - often brass, copper, sterling silver or stainless steel. The result looks like gold but contains only a fraction of the precious metal. Anyone wanting to know the true material value of a gold-plated item 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 microns | Jewellery, electronics, medical technology |
| Fire gilding (amalgam) | 1 - 30 microns | Historic sacred art, restoration |
| Mechanical plating (rolled gold / doublé) | 10 - 100 microns | Watch cases, high-end accessories |
| PVD plating (vapour deposition) | 0.1 - 1 microns | Watches, design objects |
| Gold-leaf application | 0.1 - 0.5 microns | Architecture, bookbinding, gastronomy |
Electroplating is the most widely used process today: the workpiece is immersed as a cathode in a gold-bearing electrolyte bath; a direct current deposits gold ions onto the surface. The layer thickness is precisely controllable and, for costume jewellery, is often only 0.5 microns - too little to register in a price valuation.
Historic fire gilding mixed gold with mercury into an amalgam, which was applied and then heated; the mercury evaporated and the gold remained bonded. This process is now banned owing to its toxicity and is permitted only in restoration under strict protective measures.
Gold plating vs. related terms
- Vermeil: gold plating on sterling silver (>= 925) with at least 2.5 microns of gold; a legally protected term in France and the USA.
- Rolled gold / gold doublé: a mechanically rolled gold layer (>= 10 microns), firmer and more durable than electroplated coatings.
- Rhodium plating: an analogous process using rhodium instead of gold, common on white-gold jewellery for brightening.
Marking and legal position
In the UK and EU, gold-plated items must not be described as "gold". Permissible terms are "gold-plated" or the layer thickness in microns. If there is no fineness stamp, it is clear the item is not a solid precious-metal product. Buyers value gold plating accordingly low when buying scrap gold - the purchase price calculator shows why: the actual gold content of an electroplated 10 g piece of jewellery with a 1 micron layer is typically less than 5 mg of gold.
Durability and care
Longevity depends heavily on the layer thickness and the base metal:
- Thin electroplated coatings (< 1 micron) wear through at contact points within months.
- Vermeil and doublé last several years to decades with careful handling.
- Acids, sweat, chlorine and mechanical stress accelerate wear.
- Re-plating is possible if the base 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 solid gold coins from gold-plated copies.
In brief
Gold plating is a surface finish, not a gold product - the precious-metal content is vanishingly small and has little effect on the material value. Anyone who values genuine gold content should look for a fineness stamp and buy investment gold of verified quality.