Reference
Jewellery manufacturing glossary
41 terms used across the ten stages of jewellery manufacturing, defined plainly — from wax setting and spot drilling accuracy through investment, burnout and induction melting to XRF assay and CVD screening. Where a term names equipment we supply, it links to that machine.
Written for people buying or running the machinery rather than for a dictionary. Where our catalogue publishes a figure we quote it; where it does not, you will find the term explained without one.
Stage terms
Design, moulding and wax
- Direct-castable resin
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A 3D printing resin formulated to burn out cleanly in investment, so the printed pattern goes straight into the flask in place of a wax. Our DC Black, DC Yellow and DC Green are direct castable.
See the equipment - Non-castable resin
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A printing resin intended for fit checks, client approvals and master models that will be moulded rather than burned out. Casting a non-castable pattern ruins the flask. Our NC Red and NC Red CWR are non castable.
See the equipment - LCD, DLP and MJM
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The three printing technologies in our range. LCD gives the largest build volume per rupee, DLP the finest XY resolution for detail work, and MJM wax jetting the highest daily throughput and tightest dimensional accuracy for production wax.
See the equipment - Vulcanising
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Curing raw rubber around a master model under heat and pressure to produce a reusable mould. Stage two of the ten-stage factory workflow, between printing the master and injecting wax.
See the equipment - Wax injection
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Filling a rubber or silicone mould with molten wax, usually under vacuum, to produce repeatable wax patterns. Stage three. The quality of this stage governs how well the setting stage performs — a poor wax cannot be rescued by a good setting machine.
See the equipment - Sprue
- The wax channel through which molten metal enters the mould cavity during casting. Wax patterns are attached to a central sprue to form a tree before investing.
Stage terms
Diamond and stone setting
- Wax setting
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Placing stones into a wax pattern before casting, so the metal is cast around them. Stage four of ten, and the stage where automation changes the economics most sharply.
See the equipment - Channel setting
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Stones set in a continuous groove between two walls of metal, with no individual prongs. One of the four setting types our machines support, alongside push, micro and prong.
See the equipment - Push setting
- A setting style where metal is pushed over the girdle of the stone to hold it, rather than gripped by prongs. Supported across the Semsons setting range.
- Micro setting
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Very small stones set close together, worked under a microscope. Micro setting is largely hand work at stage seven of the workflow — it is the part of setting automation does not replace.
See the equipment - Prong setting
- Stones held by individual metal claws. One of the four setting types listed for our automatic setting machines.
- Spot drilling accuracy
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How precisely a setting machine places each seat relative to its programmed position. All four Semsons setting machines hold plus or minus 0.02 mm, so accuracy is not what separates the models — throughput, nozzle count, station count and footprint are.
See the equipment - Suction nozzle
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The vacuum tip that picks up a stone and places it into the wax. Nozzle count is the main throughput lever across our range: three on the Mini Pro, four on the ST-3D 1000, eight on the ST-HDSSM.
See the equipment - Five-axis motion control
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The controller architecture that coordinates the machine's linear and rotary axes so a nozzle can reach a seat at the correct angle. Every Semsons setting machine runs an industrial-grade five-axis motion controller on a control system we developed in-house.
See the equipment
Stage terms
Investment, melting and casting
- Investment
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The gypsum-based refractory slurry poured around a wax tree and allowed to set, forming the mould. Vacuum mixing removes air that would otherwise print as surface defects on the casting.
See the equipment - Burnout
- Heating the invested flask in a furnace so the wax melts and burns away, leaving a clean cavity for metal. Stage five. A resin that is not formulated to burn out cleanly leaves residue and ruins the cast.
- Induction melting
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Melting metal by inducing current in it directly, rather than heating it with a flame. Faster, cleaner, more uniform and more controllable, with reduced heat-induced oxidation — and flameless, silent operation at the bench.
See the equipment - IGBT
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Insulated-gate bipolar transistor — the switching technology behind every induction melting machine in our range. It is what allows precise, efficient power control at the 3.5 kW to 12 kW output levels the range spans.
See the equipment - Bottom pouring
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Pouring metal from the base of the crucible rather than tipping it from the top. Because oxide and dross float, bottom pouring means the cleanest metal enters the flask first.
See the equipment - Vacuum casting
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Casting under reduced pressure so gas is drawn out of the metal and the mould fills more completely. Reduces gas porosity, which is one of the two defects that most often send a flask back.
See the equipment - Porosity
- Voids inside a casting, caused by trapped gas or by metal shrinking as it solidifies. It is usually invisible until polishing opens it up, which is why it is expensive.
Stage terms
Polishing and finishing
- Magnetic polishing
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Bulk finishing using fine magnetic pins driven by a rotating field. Because the pins are small and highly mobile they reach into gallery work, under bezels and inside detail that larger media cannot enter.
See the equipment - Vibratory finishing
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Bulk finishing using media in a vibrating bowl. Better than magnetic for general deburring and even surface finishing across a batch. Most production floors run both.
See the equipment - Electro polishing
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Brightening a surface electrochemically rather than mechanically, so it does not round detail the way aggressive mechanical polishing can. Stage nine, final polishing.
See the equipment - Ultrasonic cleaning
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Cleaning by cavitation in a liquid bath — microscopic bubbles collapse against the surface and lift compound out of detail and recesses. Skipping the cleaning steps between stages is the usual reason a final finish looks patchy.
See the equipment - Sand blasting
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Propelling abrasive media at a surface for preparation or for a deliberate matte finish. Available wet and dry.
See the equipment
Stage terms
Marking, welding and lasers
- Laser marking
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Changing a surface with a focused beam to leave a permanent hallmark, purity stamp, logo or serial number. Removes almost no material, and happens near the end of production at stage eight.
See the equipment - Laser cutting
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Removing material with a focused beam to separate or shape metal. Happens early, around design and moulding — a different job from marking, and a different machine.
See the equipment - Laser welding
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Joining, repairing or building up precious metal with a focused pulse instead of a flame. Because heat is delivered locally rather than spread across the piece, it can be used close to set stones and finished surfaces.
See the equipment - YAG laser
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Yttrium aluminium garnet — the solid-state laser source in our jewellery welding machine, catalogue-specified as single doped at 200 W output and 150 J single pulse energy.
See the equipment - Pulse ramping
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Shaping how power is delivered across the pulse rather than dumping it all at once. In practice it gives cleaner welds with less spatter and less cracking on sensitive alloys.
See the equipment - Pulse width
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How long each laser pulse lasts, specified at 0.1 to 20 ms on our welding machine. Short pulses deliver energy before heat can spread, which is what makes welding beside a stone possible at all.
See the equipment - Hallmarking
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Applying the official mark that certifies the precious-metal content of a piece. In a modern factory this is a laser marking operation at stage eight, before final polishing.
See the equipment
Stage terms
Testing, measurement and gemology
- XRF
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X-ray fluorescence — a non-destructive method of determining what a piece is actually made of by measuring the characteristic X-rays its elements emit under excitation. The sample is not cut, scraped or dissolved.
See the equipment - Non-destructive testing
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Any test that leaves the item intact and saleable. It is why XRF suits finished jewellery, incoming scrap and customer walk-ins equally.
See the equipment - Fineness and karat
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Two ways of stating precious-metal purity. Fineness is parts per thousand (999 fine); karat is parts per twenty-four (24kt). Both of our benchtop analyzers are catalogue-specified at plus or minus 0.03 percent on gold.
See the equipment - ppm
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Parts per million — the trace concentration level the Signet Si-Pin is specified to detect down to, against a 1 percent floor on the FSDD. If trace detection matters to your work, that difference is the whole decision.
See the equipment - CVD diamond
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Chemical vapour deposition — one of the processes for growing diamond in a laboratory. A standard thermal diamond tester cannot separate it from natural stone, which is what a CVD tester is for.
See the equipment - Girdle
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The band at the widest part of a cut stone, where the crown meets the pavilion. A girdle reader magnifies any inscription laser-marked onto it.
See the equipment - Refractometer
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An instrument that identifies a gemstone by measuring how much it bends light. A core gemological instrument rather than a machine.
See the equipment - Sieve
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A graded screen used to sort loose stones by size. With an assorting lamp, tweezers, a loupe and a carat scale, it is the minimum equipment a sorting bench needs.
See the equipment
Still deciding
A term is not a specification
Knowing what bottom pouring is will not tell you whether you need it. Send us your designs, your volumes and your incoming power supply, and we will tell you which stage is actually limiting your output — including when the honest answer is that you do not need a new machine yet.