Last updated: October 2026
By Jack Lv, General Manager — 925 sterling silver and GRA moissanite manufacturing in Foshan since 2011
Silver jewelry fails inspection in a small number of repeating ways: porosity and gas holes from casting, stones that are loose or missing, plating that is dull or worn through, blackened solder joints, dimensional and weight deviation, and surface scratches from uneven polishing. Each one can be written into a purchase specification as a measurable requirement, which is what makes it findable at inspection rather than arguable after delivery.
Porosity and gas holes, loose stones, plating that wears through, weak solder joints, and dimensional drift between the sample and the bulk. They dominate because four of the five are invisible on a photograph and only appear after wear or after a customer opens the box.
Defects in silver jewelry cluster. They come from a handful of process steps, and each one appears at a predictable point in the workflow. If you know where a defect is created, you know which inspection gate can catch it and which specification line prevents it.
The table below maps the main families to their origin and to how they present when the parcel is opened.
| Defect family | Where it is created | How it presents to the buyer |
|---|---|---|
| Porosity and gas holes | Casting, from gas trapped in the metal or from a poorly filled mould | Pits on a supposedly polished surface, often visible only at an angle or under magnification |
| Loose or lost stones | Stone setting, from an under-sized seat, weak prong contact or a burr left in the seat | A stone that rotates or rattles on arrival, or a missing stone in a returned piece |
| Dull or worn plating | Plating, from thin deposit, poor surface preparation or contamination in the bath | A finish that looks flat at unboxing, with base metal showing at edges and high wear points |
| Blackened solder joints | Assembly and soldering, from oxide left in the joint or from solder that does not match the alloy | Dark lines at joints, splayed discolouration around a repair, or tarnish that starts at the joint |
| Dimensional and weight deviation | Casting, forming or finishing, from tool wear and from grinding metal away | Pieces that do not fit a size chart, components that do not assemble, or a batch lighter than the approved sample |
| Scratches and uneven polish | Polishing and handling, from coarse compound, mixed work in one barrel or unprotected storage | Sleeve marks, flat patches where detail should be crisp, and fine scratching across a plain surface |
Write a maximum pit diameter and a maximum count per surface area, and name the inspection light. Without a number a defect is an opinion, and an inspector on the factory floor will resolve the opinion in the factory's favour.
Porosity is the defect buyers most often accept without knowing it, because it often needs magnification or a raking light to see. A specification that says the surface must be free of pits is almost unenforceable. One that names the inspection method, the light condition and the magnification is enforceable.
Porosity cannot be polished out. It sits below the surface, so polishing a porous casting removes metal, exposes further pits, and leaves a piece that is thinner than the approved sample. That is why porous castings should be rejected rather than reworked.
Specify the setting type, the prong count and a pull or probe test per batch rather than per piece. A loose stone is the defect most likely to reach your customer, because it usually passes a visual check and fails in wear.
A stone that falls out is the claim that costs the most, because it damages the customer relationship as well as the piece. The specification has to define what tight means, and it has to define when the check happens.
Timing matters more than most buyers realise. Setting faults are easiest to detect before plating, and harder afterwards, because a piece that has already been plated cannot easily be re-seated without marking the finish. Nabest runs setting checks at the in-process stage for exactly this reason.
State the thickness in microns and the coverage areas, then verify on a sample from the bulk rather than on the pre-production sample. Plating thickness is the single line where a cheaper quote most often hides, because it is invisible to the eye at delivery.
Plating is the specification most often written as an adjective. Plated in white rhodium tells an inspector nothing they can measure. Plating thickness stated in microns, controlled at the plating line and recorded per lot, tells them exactly what to check.
Two honest trade-offs belong in the conversation with your supplier. A thicker deposit costs more and takes longer, and on fine detail a heavy deposit can soften the crispness of a pattern. Thin plating also fails fastest at the points that rub, so the specification should name where the plating will be examined, not only how thick it should be.
Specify joint strength by a pull test and polishing by a named standard finish with a reference photo. A reference photo settles most polish disputes because it converts a matter of taste into a comparison.
Solder faults are visible and predictable. They appear as a dark line at a joint, as a patch of discolouration around a join, or as a flow of solder onto a surface where it should not be. A specification should require the joint to match the surrounding metal in colour after finishing, and to be free of oxide and of visible solder spread.
Polishing faults are the mirror image: they are about what should have been removed and what should not have been removed. Written carelessly, the requirement becomes an instruction to polish everything flat, which destroys the design and the weight. Written properly, it protects detail as well as removing marks.
Give a nominal plus or minus tolerance for the critical dimensions and for finished weight, and state which dimensions are critical. Weight tolerance matters commercially as well as technically, because on a silver piece it is also a proxy for how much metal you paid for.
Dimension and weight are the two properties that catch everything else. A batch that is light usually means metal was removed during finishing, which often accompanies porosity repairs and over-polishing. A batch that is dimensionally out of line usually means a worn mould or die, which drifts gradually rather than failing suddenly.
Both should be measured with instruments rather than judged by eye, and both should be tied to the approved sample rather than to a drawing that nobody has compared against a physical piece.
AQL sampling tells you whether a batch is acceptable at an agreed defect rate; it does not prove the batch is free of the defect you care most about. It is a decision rule, not an inspection of every piece, so pair it with a full check on the one characteristic that would end the order.
AQL stands for Acceptable Quality Limit. It is a sampling method in which a defined number of pieces is drawn from a lot and inspected, and the lot is accepted or rejected against a threshold number of defects in defined classes, usually critical, major and minor. It is a lot-level decision rule, not a measurement of individual pieces.
Its limits are worth stating plainly, because buyers often treat an AQL result as a guarantee. A passed inspection does not mean the lot contains no defective pieces. It means the number of defects found in the sample stayed inside the agreed threshold. A small sample can miss a fault that appears later in the same lot, and a defect class that was not defined at inspection cannot be counted against the supplier afterwards.
AQL also cannot fix anything. Applied only at the end of production, it can only sort good pieces from bad ones. Applied at the in-process stages, the same method prevents value being added to a piece that will be rejected.
Pre-production sample catches specification errors, in-line inspection catches process drift, pre-shipment inspection catches the bulk, and incoming inspection catches freight damage. Skipping the in-line gate is the commonest cause of a pre-shipment failure, because by then the whole batch carries the drift.
Nabest runs four inspection gates, IQC on incoming material, IPQC during production, FQC on finished goods and OQC before shipment. The gates are not interchangeable, and the clearest way to write a specification is to say which gate each requirement belongs to.
| Gate | Applied to | Catches | Cannot catch |
|---|---|---|---|
| IQC, incoming material | Silver alloy, loose stones, findings, clasps, chains, packaging | Wrong alloy grade, wrong stone grade or size, undersized findings, damaged packaging | Anything created later on the line |
| IPQC, in process | Wax or dies, castings, settings, polishing, plating | Porosity at casting, loose seats before plating, plating appearance and thickness at the tank, joint faults before finishing | Defects introduced by packing or handling after the stage |
| FQC, finished goods | Assembled, finished and plated pieces | Stone security, surface finish, solder colour, dimensions, weight against the sample, function tests | How the batch is packed, labelled or counted |
| OQC, before shipment | Packed cartons, labels, paperwork | Short or over shipment, mixed models, wrong or missing labels, packing damage, documentation errors | Fine surface defects, because it inspects the packed lot rather than re-finishing every piece |
One page, one line per characteristic, each with a nominal value, a tolerance and a test method. Tie it to your commercial terms: Nabest quotes a minimum order quantity of 10 pieces per style, with sampling at 5 to 7 days and bulk production at 15 to 20 days, which is the window in which a specification dispute has to be settled.
A specification sheet that survives a production run has four sections: material, dimensions and weight, finish and function, and inspection. Every line in it should be checkable by someone who was not in the negotiation, with an instrument or a defined viewing condition, and against a physical approved sample.
Keep it short enough to be read at a bench. A specification that runs to many pages and repeats itself is usually ignored, and the paragraphs that get ignored are the ones about plating and finish, which is where the smallest differences show up most visibly to a customer.
Finally, tie the sheet to your commercial terms. Nabest quotes a minimum order quantity of 10 pieces per style, with sampling at 5 to 7 days and bulk production at 15 to 20 days, which means the specification is finalised at sampling. Changing a critical line after sampling has begun restarts the clock rather than adjusting it.
Lost or loose stones, followed by plating complaints. Stones cause the highest cost per claim because the piece usually cannot be repaired by the customer. Plating causes the highest volume of complaints because it is the first thing a customer sees and the property most affected by wear, perfume and household chemicals.
No. AQL sampling decides whether a lot is accepted or rejected against a threshold of defects found in a sample. It is a lot-level rule, not a promise about individual pieces, and a defect class that was not defined before inspection cannot be counted against the supplier afterwards.
As a thickness in microns with a tolerance, controlled and recorded at the plating station, plus named appearance requirements under a defined viewing condition and named inspection points where wear-through shows first, such as the inside of a band or the tips of prongs. Adjectives are not checkable and should not appear as the only requirement.
At the in-process gate, immediately after casting and before polishing or plating. Porosity sits below the surface, so polishing a porous casting removes metal and exposes further pits, and plating over it hides the fault until the customer wears the piece.
A supplier's own gates are a process control, and they are worth asking about in detail. Your own inspection, whether by AQL sampling at the factory before dispatch or by a third-party inspector on site, is the evidence that the goods you paid for are the goods that were specified, which is a different question.
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