Why does white gold need rhodium plating?

Your white gold ring is turning yellow, most of all underneath, where it rubs. You're wondering whether it's damaged, whether you were sold something other than what you were told, and whether it can be put right.

It isn't damaged. You weren't sold the wrong thing. What's happening was built in on day one, and it can be corrected.

White gold isn't white

That's the starting point, and it surprises almost everyone.

Gold is yellow. It always is. To make white gold, it's alloyed with pale metals — palladium, silver, sometimes others — which soften the colour without removing it. An 18ct white gold is still gold at 750 parts per thousand: three quarters of the metal is yellow. What comes out of the alloy is a slightly grey white, faintly warm, and nothing like the bright white of the rings in the window.

That bright white comes from somewhere else. It comes from a layer of rhodium laid over the surface — a metal from the platinum family, very white, very hard, applied a few microns thick. That's rhodium plating.

Put simply: the white you like on a white gold ring is a finish, not the colour of the metal underneath.

Why it wears

A few microns is very little. It's finer than a hair.

The layer doesn't flake or peel: it thins, through friction, until the gold beneath begins to show. That's why the yellowing never appears everywhere at once. It starts where the ring rubs most:

• the underside of the band, against the next finger and against everything you touch;

• the edges, and anything that stands proud;

• under the claws, on claw-set rings.

The top of the ring often stays white far longer. A ring that yellows underneath and stays bright on top has nothing wrong with it. It's simply being worn.

How often it needs redoing

I won't give you a single figure, because it would be wrong for half the people reading.

The interval depends almost entirely on how you wear the ring. What shortens it:

• Wearing it constantly, overnight included, rather than in the evenings.

• Using your hands: gardening, cooking, sport, climbing, manual work — and a keyboard, for some ring shapes.

• Which finger. A wedding band worn against an engagement ring wears at both the points where they meet.

• Household products, chlorine in pools, and hand sanitiser used several times a day.

• The shape. A fine, rounded band wears faster than a wide, flat one, because the same wear is concentrated on less surface.

In practice, some rings want redoing after a year; others go several years without anyone noticing a thing. The real answer is: when it starts to bother you. It's a preference, not a deadline.

What's actually done

The work itself is straightforward and well established.

The ring is cleaned, then polished to take out the fine scratches and whatever remains of the old layer. It then goes into a bath where rhodium is deposited by electrolysis. It comes out white and bright, as it was on the first day.

Two things are worth knowing beforehand.

Polishing removes a small amount of metal. Very little, but not nothing. A ring plated ten or fifteen times over a lifetime thins slightly. On a fine band worn constantly that eventually counts — which is an argument to weigh when you choose the thickness, rather than something to worry about afterwards.

Stones call for care. Diamonds are untroubled. Emeralds, opals, treated or fragile stones, and anything glued rather than set, need looking at first. Sometimes the ring is plated with the stone protected; sometimes it isn't plated at all.

Can it be avoided?

Yes, in three ways.

Choose platinum. It's white all the way through, with no layer and no treatment. It scratches and takes on a soft patina over the years, but it doesn't yellow, because there's nothing on the surface to wear away. That's the real argument for platinum, and I set it out in White gold or platinum?.

Wear white gold unplated. There are white gold rings left exactly as they come: a warm, slightly grey white that doesn't change, because there's nothing to lose. Few people ask for it, and it ages very well. It's a real option, as long as you've seen it before you commission — the colour isn't the one in catalogue photographs.

Change the colour. Many people who arrive with a yellowed white gold ring look at what's showing through and find they prefer it. Yellow and rose gold ask nothing of you in upkeep, ever.

If your ring has yellowed

It can be put right. That's true of nearly every white gold ring, including ones that didn't come from me and ones that were inherited.

The first thing I look at isn't the colour but the setting: a ring worn enough to lose its rhodium has often worn its claws too. Better to check both at once — there's no sense making a ring bright again if a claw gives way six months later.

Bring it in, or write to me with a photograph taken in daylight. I'll tell you what it needs and what that involves, before you decide anything.

The boutique-atelier is at Rue Ancienne 3, Carouge.