The Soft-Soldered Shank and the Second Signature
An 18 kt white gold ring comes in for attention: a 2.1 mm wide shank worn to about 0.7 mm at the base, an old repair showing a grey, lumpy joint, a four-claw setting holding a 0.25 ct diamond with worn claw tips, and a 750 stamp beside a maker's mark but no current assay mark. XRF of the repair joint shows tin and lead. The client wants the ring taken from EU size 52 to EU size 56, the claws re-tipped and the whole ring polished by Saturday, and she refuses to let the stone be removed "because it might get switched". The shop has a laser welder. Saturday is four working days away, and the shop's repair docket is currently a single line on an invoice with no photographs.
1. Assess the job and state what you would tell the client before any tool touches the ring.
Read the worked answer
Findings and their consequences.
- Tin/lead in the old joint. Lead in gold causes hot shortness - the alloy cracks when worked hot - and contaminates the bench, the solder and the pickle. It cannot simply be re-flowed; the contaminated section must be cut out and replaced, and any solder used afterwards must be lead-free.
- 0.7 mm shank at the base. Below a sensible minimum for an 18 kt ring that will be worn daily. This is a half-shank replacement, not a sizing.
- Worn claws. Re-tipping means soldering within a millimetre of the diamond. Diamonds survive brief, flux-protected, heat-sunk soldering, but mops and burrs near a set stone can catch a claw and lift it - the stone is at risk at the polishing stage even if it survives the torch.
- Hallmark. The 750 stamp is not a substitute for an assay mark after a repair of this scale. The article must go for assay; that affects the Saturday deadline.
What the client is told, in writing: the shank is worn through and will be replaced; the old joint contains lead and is being removed; her refusal to have the stone removed is her right, but it transfers a defined risk to her, and I will not guarantee the stone. She signs the docket with that statement, or the job is declined.
2. Calculate what is involved in taking the ring from EU 52 to EU 56, and explain why the naive circumference figure is not enough.
Read the worked answer
EU ring sizes are internal circumference in millimetres, so:
- Size 52 → internal diameter = 52/π ≈ 16.55 mm
- Size 56 → internal diameter = 56/π ≈ 17.83 mm
- Increase in circumference = 4 mm; increase in diameter ≈ 1.27 mm
So roughly 4 mm of extra shank length is needed at the base.
Why 4 mm is not the cutting list:
- Half-shank replacement, not an insert. Because the base is worn, the correct move is to cut out the worn section and the lead-contaminated joint and fit a new piece of matching width, thickness and alloy. That piece must be about 4 mm longer than the gap, plus an allowance for the saw kerf and joint preparation, plus a small surplus because the soldered joint pulls slightly as it freezes.
- Stretching is not an option. Four sizes cannot be obtained by hammering out on a mandrel, especially on a ring with a setting; it thins the shank and distorts the head.
- The head moves. Opening the ring changes the geometry of the setting; the claws must be checked and the ring re-rounded on the mandrel, then sized on a ring gauge, not with calipers across a sprung ring.
- Alloy matching. 18 kt white gold may be nickel-white or palladium-white; the shank must match in colour and hardness or the repair shows after polishing.
- Finishing losses. Filing and polishing remove metal, so the finished size must be checked after polishing, not before.
3. State the quality-control checks, records and professional obligations you would complete before the ring leaves the shop.
Read the worked answer
Records before starting: photographs of the ring, the worn shank, the old joint and the claws; weight; measured size; XRF result of the joint; the client's signed instruction about the stone and the risk statement; a proper docket with a job number, not a line on an invoice.
During the job: lead-bearing material cut out and segregated, not filed into the general scrap; dust from white gold and from lead-bearing solder kept out of the general atmosphere and disposed of properly; no eating or drinking at the bench; stones checked at every stage.
Checks before it leaves:
- Size confirmed on a ring gauge.
- Setting: every claw tested individually for movement, tips dressed and polished, stone checked under the loupe for new abrasions or chips.
- Joint: no pits, no visible solder line, no colour mismatch under the polishing light.
- Polish: no compound trapped around the setting.
- Weight after finishing recorded against the intake weight and explained to the client.
- Hallmark status: the piece is submitted for assay, and the client is told why and when.
Professional obligations: a written warranty limited to the work done (the shank and the claw tips), an explicit statement that the stone was refitted at the client's request and that no guarantee is given for it, and a clear record of who did what and when. If the stone is later found damaged, that documentation is the difference between a dispute and a defensible position.