Re-plating and repairs

A law about mending

Here is a fact that surprises most people, including some who sell jewellery. Under the Hallmarking Act 1973, it is an offence for anyone to make an addition, alteration or repair to an article bearing approved hallmarks, unless an assay office has given its written consent.

The law is not as fierce as it sounds. It comes with sensible exceptions, written so that worn rings can be resized and tired white gold can be re-plated without a trip to the assay office. But it explains why a good jeweller will look for the hallmark before picking up a tool. A hallmark is a promise about what a piece is made of, and the law exists so that a repair can't quietly break that promise.

Signs a piece needs a jeweller

The Gemological Institute of America suggests having jewellery checked every six months. The National Association of Jewellers, the UK trade body, lists the things to look out for:

• Worn, damaged or missing claws on settings, which risk losing a stone
• Loose stones in their settings
• Loose catches and clasps, or rough links on chains and bracelets
• Any cracks in the metal
• Pearls loose on their thread, or a frayed thread
• Too much movement in hinges
• Plating wearing off white gold

Its reassurance is worth repeating too: jewellery will very rarely be beyond repair or restoration.

When plating wears

Plating is a thin layer of one metal over another, and the parts of a piece that rub against skin, clothes and other jewellery wear first. On a ring, that is often the underside of the band. The first sign is usually a change of colour where the metal underneath starts to show.

Re-plating puts a fresh layer back. In general terms, the work goes like this:

• Assessment. The jeweller checks what the piece is made of, whether it is hallmarked, and whether anything else needs repairing first, because repairs come before plating, not after.
• Cleaning and polishing. Plating copies the surface beneath it, so scratches are polished out first. The piece is then thoroughly degreased: even a film of oil can stop new plating sticking.
• Plating. The piece is hung in a plating solution containing the metal to be deposited, and an electric current carries that metal onto its surface.
• Rinsing and finishing. The piece is rinsed, dried and checked.

Stones complicate things. Some can go through the process, others can't, and a jeweller may need to protect or remove them. That is one reason re-plating is a job for a jeweller, not a kit.

For hallmarked precious metal, UK rules set out which plating metals are allowed. Silver may be plated with silver, palladium, gold, platinum, ruthenium or rhodium. Gold may be plated with gold, platinum or rhodium. Base metals such as nickel or copper must not be used, either on the surface or as a hidden layer underneath.

Rhodium and white gold

White gold is gold alloyed with white metals, and it is often finished with a thin plating of rhodium, a bright white metal from the platinum family, to make it whiter still. The National Association of Jewellers lists plating wearing off white gold among the things to have checked.

Re-plating white gold with rhodium is one of the exceptions written into the Hallmarking Act. Adding a coating of rhodium to gold, silver, platinum or palladium is not an offence, provided it is no more than 2 micrometres thick at any point. The same exception covers gold re-plated with gold of at least the same standard, and silver plated with gold, platinum or palladium. So a white gold ring can be re-plated, and gold vermeil can be refreshed with gold, without asking an assay office, as long as the layer stays within that limit.

Re-plating doesn't change the hallmark or what the ring is made of. It restores the colour of the surface.

Common repairs

Claws deserve a special word. They are small, they take every knock, and when one wears thin the stone it holds is at risk. The Gemological Institute of America notes that older claws on antique pieces are fragile, and that the vibration of an ultrasonic cleaner can shake stones loose, which is why a jeweller checks for loose stones before cleaning, not after.

Repairs and the hallmarking law

The UK rules draw a clear line between new pieces and pre-owned ones.

New hallmarked pieces

Any addition, alteration or repair to a new hallmarked article needs the written consent of an assay office. The UK Assay Offices' guidance adds that once a piece has been hallmarked, combining the hallmarked part with other parts that weren't assayed with it is an offence too. In practice this matters most to makers and retailers, before a piece is sold.

Pre-owned pieces

A hallmarked piece that is not new can have metal added without consent, as long as all of these are true:

• The piece keeps its character and purpose. The guidance's example: a spoon must not become a fork.
• The added metal is the same precious metal, and at least the same standard of fineness.
• The addition is no more than 1 gram of gold, 5 grams of silver, 0.5 grams of platinum or 1 gram of palladium.
• The addition is no more than half the weight of the piece before it was added.

Anything beyond that, the guidance says, must be re-submitted to an assay office. And separately from repairs, it is an offence to remove, alter or deface a hallmark without consent.

When repair isn't worth it

Almost anything can be repaired. Whether it should be is a judgement, and it usually turns on three questions.

• What is it made of? Solid gold, silver and platinum hold their value and can be soldered, resized and re-plated again and again. Plated base metal is a different matter: re-plating restores the colour, but it can't undo corrosion or wear in the metal beneath.
• How much is left? A chain broken once is a quick job. A chain that has worn thin all along its length, or a ring band worn very thin, may keep breaking.
• What does it mean to you? A grandmother's ring is worth mending whatever it weighs. A piece bought for one summer may not be.

A jeweller will tell you honestly which side of the line a piece falls, and many will give an estimate before starting work.

Back to the law

The Hallmarking Act's rule on repairs sounds strict, but its exceptions describe exactly the work a good jeweller does every day: matching metal for metal, keeping additions small, re-plating within a hair's breadth. A ring that has been resized, re-tipped and re-plated over fifty years should still be exactly what its hallmark says it is. That is the point of the law, and the point of a good repair.