How to Restore the Shine to Gold (and What Cleaning Can't Fix)

A gold ring or chain that has lost its glow usually isn't ruined. But "dull" can mean several different things with gold, and soap and water fix only one of them.

In this guide I'll show you what cleaning can do, what only a jeweler can do, and why the popular foil-and-salt trick for gold is unproven.

Pure gold doesn't tarnish. Its alloys can.

GIA explains it plainly: "while pure gold doesn't tarnish, the alloys within gold jewelry can tarnish," and "the lower the karat, the more susceptible the jewelry is to tarnishing." The World Gold Council gives the arithmetic: 24 karat is pure gold, while 18 karat is 75 percent gold and 25 percent other metals, "often copper or silver." Those metals give gold its strength and its color, and they are also what can darken.

They are what harsh chemicals attack, too. GIA's advice for every karat: "Avoid chlorine and harsh chemicals because they can damage the alloying metals."

What cleaning can do: remove the film

Most dull gold is simply dirty, with skin oil, soap and lotion. For that, the answer is the gentle bath. GIA recommends water with a few drops of mild dish soap and a soft toothbrush. A jewelry insurer gives the same advice for gold, adding: "Steer clear of any soap with unknown ingredients." Use warm water, not hot, especially if the piece has stones: GIA warns that heat and sudden temperature changes "may also fracture some gems."

What cleaning can't do: scratches

Gold is soft. GIA notes that yellow gold is "more prone to scratches, dings and damage," and that 24 karat, the purest, is the softest of all. A diamond can scratch any of the precious metals used for settings, so a gold chain tossed in a drawer with a diamond ring can come out scratched.

A scratched surface needs polishing, and polishing is abrasive. The Canadian Conservation Institute, writing about brass and copper, explains the general rule: polishing "removes tarnish and some surface metal," and "repeated polishing results in loss of surface detail." On rose gold, GIA notes that a piece may need polishing from time to time to remove patina.

So leave polishing to a jeweler, and not too often. Polish a ring every year for decades, and there is less metal left in it.

White gold turning yellow: it needs rhodium

Most white gold isn't as white as it looks. The World Gold Council says white gold "is usually plated with rhodium to create a harder surface with a brighter shine." Underneath, GIA says, white gold with more gold in it "displays a slight yellow tint."

And rhodium wears. GIA: "Rhodium plating will wear away gradually over time, requiring the ring to be replated occasionally." As it wears, the ring "may start to appear warm in color." No cleaner fixes that, because it isn't dirt. It needs a jeweler and fresh rhodium. GIA suggests taking white gold off before you shower, which helps keep its luster and means less replating.

About the trick in the video

The video above shows two methods. The first lines a bowl with aluminum foil, adds a teaspoon of baking soda and a teaspoon of salt, pours boiling water over the gold, waits about 10 minutes, then brushes. It rightly says not to use this on gold set with precious stones. The second is baking soda and hot water, then a soft brush with dish soap, a rinse and a microfiber cloth.

The brush and the dish soap are exactly what GIA recommends. The rest deserves a plain word of caution:

• Baking soda. The American Gem Society calls it "too alkaline for cleaning jewelry safely."
• Boiling water is a burn risk, and it isn't what the trade associations use.
• The foil is unproven. The foil bath is a reaction that turns silver tarnish back into silver. When GIA researchers studied dark spots on high-purity gold jewelry, they found silver sulphide from surface contamination, not corroded gold. We found no gemological, conservation or chemistry source showing that foil and salt clean gold jewelry.

Any brightening of low-karat gold may come from the hot water loosening grime, or from the bath acting on the silver or copper in the alloy, but nobody has published a test. Our view: the second method without the baking soda, which is simply the gentle bath, is the safe way.

What no home cleaning can do. It can't remove scratches; only a jeweler's polish does that, and it takes a little metal each time. It can't bring back worn rhodium on white gold. And it can't put back metal that years of polishing have taken away.

Volume V, Clean It Right, covers yellow, rose and white gold, platinum and palladium, includes a once-a-year look at your rings, and checks the popular cleaning tricks against GIA, the American Gem Society and museum conservators.