Should you clean or polish gold and silver before you sell it?

01

Why polishing costs the seller and not the buyer

Cleaning silver feels like courtesy. Nobody wants to hand over a grey tray, and the instinct to present things properly is a good one almost everywhere else. Here it works against you, for a mechanical reason that is rarely spelled out.

A polishing cloth does not lift tarnish off the way a duster lifts dust. Abrasive cleaners cut, and what they cut is the surface. Icon's guidance on the care of silver says that wadding, creams and rouge sticks remove much more of the silver surface than chemical methods, and that repeated cleaning wears away the silver and any engraved decoration or inscription. Even for light cleaning, it reminds owners that each time you do this you are removing a little of the original surface.

Now look at where the cloth actually touches. It bears on the high points: the crest of a rim, the shoulder of a spoon stem, the raised edge of a foot. A hallmark is struck into the metal, and the metal around it stands proud. Decades of polishing take the struck edges down first, and a mark goes from crisp to soft to unreadable.

The weight lost matters less than people fear, and the identification lost matters more. One polish takes too little metal off a tray to notice on a scale. Thirty years of Christmas polishing can take enough off a set of marks to leave a piece that nobody can attribute, and the hallmarks guide shows how much rides on those few millimetres.

02

Coins are the stricter case

Everything above applies to a coin twice over, and here the loss is not a matter of degree.

A cleaned coin announces itself. The surface of a coin as it left the press has a particular texture, and cleaning replaces it with a flat brightness and fine parallel scratches that anyone who handles coins reads at a glance. It cannot be undone or hidden. The Royal Mint's advice on looking after bullion is that you do not need to clean gold, and that doing so may damage a mint finish. It asks owners to pick coins up by the edge, finger and thumb around the rim, without touching the faces.

This costs more on a coin than on a spoon because a coin can carry value that has nothing to do with its metal: a scarce date, a mint mark, a good strike, an original surface. Cleaning removes precisely that part. A sovereign that would have sold as a coin becomes a sovereign sold as gold, and the difference between the two is the subject of the sovereigns guide.

03

What tarnish actually is

People clean silver because they read tarnish as neglect. It is not, and understanding what it is makes the decision easier to live with.

Icon describes it as a gradual discolouration caused by sulphur compounds in the air: the metal turns pink, then brown, then a very dark grey or black with a slight iridescent sheen. Wool, silk and leather all contain sulphur compounds, which is why a canteen in its lined case can go darker than a tray on a sideboard. Skin plays a part too: the salts and greases on fingers are corrosive and can mark a polished surface for good.

That film is thin and superficial. It has no bearing on what the piece weighs, what the metal beneath it is, or what a test finds. It is not dirt in any sense that matters, and it is not a sign that a piece has been badly kept.

Tarnish is also worth reading rather than removing. Where a gilded or plated surface has worn, the metal underneath often tarnishes differently from the metal on top, and the pattern is a clue to how the piece was made. A gold-coloured piece going grey at the link tips is usually gilded silver. The guides to plated and filled gold and to silver plate both read surfaces this way, and polishing wipes that evidence off.

Green or crusty deposits are a different matter. Those are corrosion products of the copper in a silver alloy, and Icon advises that extensive green corrosion is a case for a specialist conservator rather than for a cloth.

04

What is worth doing before you post

Three things, none of which involves a cleaner.

1. A dry dust, and nothing moreA soft, clean, lint-free cloth or a very soft brush, used dry. Icon recommends this as ordinary housekeeping, because dust attracts moisture. Here it has one purpose: letting a camera see a mark that was under a film of dust.
2. Take off what has perishedA rotted leather watch strap, a split ribbon, a crumbling cord on a pendant, a decayed silk lining. Those shed into a parcel and mark other pieces, and none of them is part of what is being weighed. Keep anything you take off, in case you want it with the piece later.
3. Photograph the marks as they areLight across the mark rather than onto it, the camera as close as it will focus, three or four frames and keep the sharpest. A tarnished mark photographs perfectly well, and in some lights the darkened recesses make it easier to read than a polished one.

That is the whole of it. The posting guide covers packing once you have decided what is going, and the photo route is where the pictures go.

05

Seller risks and exceptions

• Dipping before you ask. Chemical silver dips work by dissolving the tarnish and leave a very reactive surface that darkens again quickly. On a piece with an original patina, and on anything with a collector following, that is not reversible.
• Using the wrong cleaner entirely. Icon warns against brass and chrome cleaners on silver, which contain harsher abrasives, and against electrochemical cleaners, which deposit a layer of another metal on top and permanently obscure the original finish.
• Scrubbing a mark to read it. The mark is what you are trying to preserve. Change the light instead, or move the camera.
• Cleaning a piece you are about to send to a specialist rather than to a buyer of metal. Auction houses and dealers see cleaned surfaces immediately, and a cleaned antique is a cheaper antique.
• Cleaning to make a better impression. Tarnish does not change the metal, its weight or a test result, so there is nothing to gain by removing it before you post.
• Polishing a plated piece to see whether it is silver. Plating is measured in microns and abrasive cleaning goes straight through it, which destroys evidence and answers nothing. Testing at home covers what does settle it.

06

When not to use this route

The scored checklist in antique silver or scrap sorts out the pieces that should not be sold for metal at all, and valuation, appraisal or offer sets out who to ask when a piece needs a specialist. For everyday silver, the sell silver page explains what happens once you are ready.