Rhodium plating

Rhodium is a silvery-white metal and one of the six platinum-group metals, the family that also includes platinum and palladium. Plating means depositing a thin surface layer of one metal over another. In jewellery that layer is rhodium, and it goes over metals that are not bright white on their own.

The most common case is white gold, which is gold alloyed with white metals such as nickel, palladium and zinc. White gold is usually rhodium plated for a whiter look, a better shine and protection against scratching. Rhodium can also be applied to sterling silver for a mirror-like finish and a barrier against tarnish, and some makers plate platinum rings for extra shine and scratch resistance.

There is no fixed number. Rhodium plating wears away gradually, and white gold needs occasional re-plating, but how often depends on the ring, how it is worn and how it is cleaned. Treat any promised timeline with caution.

The sign to watch for is colour. As the rhodium plating wears away, a white gold ring may start to look warm in colour, which points to the gold alloy beneath showing through. Ask your jeweller whether they will re-plate the ring when needed. Ask that before you buy, not after.

Cleaning matters too. GIA says chlorine (household bleach) and abrasives such as household cleansers or toothpaste should never be used on diamond jewellery, and that they can erode the metals in a setting. Keep them away from a plated ring as well. For everyday cleaning, see the jewellery care guide.

Rhodium plating is not always white, because rhodium can be applied in other colours. GIA's article on dark metals shows finished designs in black rhodium-plated gold and red rhodium-plated gold set with diamonds and coloured stones.

GIA does not explain how these finishes are made or how long they last. Black rhodium is still a surface layer, so ask the seller how the finish is applied, how it wears and whether it can be renewed.

In the United States, the FTC Jewelry Guides call it unfair or deceptive not to disclose a surface layer of rhodium on a product marked or described as precious metal. These are US guides, not Canadian law, but the reasoning applies anywhere: the white you see may be a coating over a different metal.

Canada's Precious Metals Marking Act names gold, palladium, platinum and silver as its precious metals, and the stamps it allows describe those metals (see precious metal quality marks). A stamp such as 14K describes the gold alloy, so it is reasonable to ask whether a white piece is plated and how it will look once the plating wears.

If you want a metal that is white all the way through, platinum and palladium are naturally white, and neither tarnishes. White gold gives a similar look with re-plating as the upkeep, and the gold vs platinum guide walks through the comparison.

Nickel is the other thing to weigh. GIA names nickel, often used in white gold alloys, as an allergen, and says white gold alloyed with palladium, or gold that contains no nickel, suits sensitive skin better. Plating is a thin layer, so over time the alloy underneath is what touches your skin. Ask which white metals a white gold ring uses.

If you are planning a custom engagement ring, metal is one of the choices to settle early. You can compare white metals in the design studio or in person at a showroom.