white gold rings, rhodium plating

Rhodium Plating: The process behind White Gold

white gold, rhodium plating

All white gold needs rhodium plating. It is this plating that gives white gold the ultra white colour which we love to use in jewellery.

White gold doesn’t naturally exist. Pure (24ct) gold, which we obtain from mining, is in fact yellow in colour. White gold is essentially a manmade metal. To be more specific, white gold is an alloy of yellow gold. White metals, such as nickel, silver or palladium are combined with yellow gold. The result is an alloy with a yellowish tint. Rhodium plating is applied to this alloy to give it the desired whiteness.

Rhodium Plating: List of frequently asked questions

1. What is rhodium?

Rhodium is a white metal belonging to the precious platinum family. It is rare, silvery-white in colour and resistant to corrosion and aggressive chemicals. It is because of these properties that it is used in the process of turning gold into white gold.

2. What is the process of Rhodium Plating?

Rhodium plating is a process whereby rhodium is deposited onto the surface of a metal using an electrical process. Using chemistry terms, the process can be explained as follows:

  • The metal that needs to be plated has a negative charge (cathode).
  • The other end of the metal is connected to another electrode, which is positively charged (anode).
  • The metal is submerged into a "plating solution" of rhodium and other ions. This solution enables the flow of electricity.
  • A supply of electricity passes through the solution when connected to the power supply. The electricity splits the ions. The positively charged ions are attracted to the negatively charged gold alloy. This slowly builds up a layer of rhodium onto the metal.

The surface of the metal needs to be perfectly smooth, clean and free of contaminants to enable the plating to bond effectively to the outside edge of the metal. Therefore, before the plating process can begin:

  • The metal must be polished and placed in an ultrasonic cleaner.
  • All the grease is removed from the metal by dipping it into salts and passing an electric current through it.
  • The metal is then thoroughly rinsed with distilled water.

The durability and strength of the plating depends on two things:

  • The amount of rhodium ions in the plating solution.
  • The length of time that the metal is left in the solution.

3. Is Rhodium Plating permanent?

No. The plating is not permanent. It fades with wearing. For this reason, the process needs to be repeated.

4. How often does it need to be reapplied?

This depends on how often the jewellery is worn and thus its wearing.

The base colour of the white gold also plays a factor. If, for instance, the base has a really yellow tinge, the gold colour tends to come through quicker. For this reason it does not make sense to rhodium plate pure yellow gold.

5. Can I rhodium plate my ring with diamond or precious gemstones?

Yes. Diamonds or gemstones do not benefit from plating. For this reason they are temporarily painted over with masking lacquer. This lacquer protects the diamonds or gemstones and avoids rhodium being deposited on them. The lacquer is easily removed when the plating process is completed.

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