Repair soldering is not hardware soldering
Jewelry soldering uses hard solder - a brazing alloy that melts above 450 C but below the melting point of the gold or silver being joined. It is not soft plumbing solder, and the joint strength depends almost entirely on preparation rather than on the heat itself. A joint that cracks within months was usually made on a dirty, ill-fitting surface, not with the wrong solder.
Solder grades and the fire-scale ladder
Hard solders come in graded melting temperatures, often labeled easy, medium, and hard (or by their flow point). The rule is a ladder: each subsequent joint in a repair must use a lower-melting solder than the one before, or the earlier joint will re-flow and open. When a ring shank is repaired and then a stone seat is soldered on nearby, the bench plans the order of operations so a low-temperature solder is never placed next to a high-temperature joint it could undo. This is why a repair that looks like one simple seam can take longer than expected - the technician is sequencing joints, not just heating metal.
Solder must also match the alloy. Soldering 18k gold with 14k solder, or soldering karat gold with filler intended for silver, leaves a visible, weaker, and often discolored joint. The karat and color of the solder are selected to disappear into the finished piece, not merely to hold it.
Fit-up before flux
The strongest jewelry joints are butted with near-zero gap. Solder is not a gap-filling epoxy; it wets and draws into a tight seam by capillary action. A joint left open like a crack gets a weak, porous bead that looks shiny but flexes under load. Before any heat, the two surfaces are filed or sanded to mate flush, checked under magnification, and held with tweezers, binding wire, or a third-hand. Repair houses also remove stones that cannot survive heat - diamonds can take it, but many colored gems, pearls, and glue-set stones cannot, and a careless torch job ruins a ring faster than the original fault did.
Flux, heat, and fire scale
Flux does the invisible work: it dissolves oxide on the metal surface so the solder can wet, and it shields the joint from further oxidation while hot. Without flux, the solder balls up and refuses to flow. With too much flux or wrong heat, the result is fire scale - a reddish, oxidized layer buried just under the surface that only appears after polishing and plagues gold work, especially in silver soldering where copper oxidation shows as dark firescale.
Heat is applied evenly around the joint, not concentrated on the solder itself. The metal is brought up to temperature as a unit; the solder follows. Heating the solder directly while the base metal stays cool creates a cold joint - solder melted but not alloyed, sitting like a foil on the surface. These fail first under ring tension.
Pickling and finishing the joint
After cooling, the piece goes to a pickle - a mild acid bath - to dissolve flux residue and surface oxides. The joint is then filed, sanded, and polished flush. A visible seam after finishing means the joint was not dressed properly; a good solder line should disappear into the surrounding metal once polished, leaving no ridge and no color difference. On a repair, the customer should not feel the joint when running a finger around the shank. If they can, it was finished in a hurry.
Typical repair joints and where they go wrong
Three repairs account for most bench soldering: a broken or worn shank, a re-tipped or rebuilt prong, and a detached earring post or hook. Shank repair cuts out the worn section and solders in a matching strip of the same alloy, sized to the existing wall thickness - a patch that does not match wall thickness leaves a hard ridge that catches on clothing. Prong re-tipping builds a small bead of solder on the worn tip and then shapes it; this is a structural joint, not a cosmetic one, and a prong tip that spins or drops after a few months was soldered to a dirty or oxidized prong, not to clean metal. Earring posts are soldered at a shallow angle so the earring hangs level, and the joint must carry the full weight of the drop against repeated tugging.
Across all three, the same failure pattern appears: heat applied to a surface that was not cleaned of polish, oils, or previous solder residue, or flux that burned out before the joint flowed. A quick wipe with a finger is not prep; the joint area is abrasively cleaned until bare metal, fluxed while clean, and heated within minutes, not left to sit.
What makes a repair joint fail
Most failed repair joints share one of three causes: a gap that was not fitted, a joint soldered with the wrong (or wrong-temperature) alloy, or heat applied to the solder instead of the metal. Less often, the underlying structure was too thin to carry the load - a shank repaired repeatedly at the same spot has work-hardened and fatigued metal that needs section replacement, not another bead of solder. A bench that tells a customer "this needs a new shank section, not a solder" is saving them a return visit.
For buyers sending inventory out for repair, ask the shop two things: what solder grade and alloy will be used, and how stones are protected during heating. Honest answers signal a shop that treats soldering as metallurgy, not as a quick weld. Read more in our repair and finishing guides, or send a faulted piece to the bench for a joint assessment.
The definition of carat weight and how it is measured are set out in the Wikipedia entry on carat weight.
Frequently Asked Questions
What ring sizes can you supply in bulk?
US sizes 5–12 including half sizes. Send a size breakdown with your order and we cast to that curve; comfort-fit inner bands reduce resize requests.
Can I order a mixed size run instead of one size?
Yes. Mixed runs are standard for wholesale: specify quantity per size and we pack and label by size at no extra labor cost.
What is the MOQ for custom ring designs?
50 pieces per design for existing molds; 100–300 pieces when a new mold or CAD model is required.
How should I price rings for retail margin?
Most partners use a 3–4x markup on FOB cost for sterling and 2.5–3x for moissanite solos, which keeps landed cost under 30% of retail.
