Jewellery Manufacturing Machinery Glossary

Automatic wax setting machine

A machine that places small stones into a wax model on its own. It lifts each stone out of a sorting tray with a suction nozzle and presses it into the wax at a position you have programmed, so the stones are already sitting in the model before it is cast. The Pro Mini sets up to 10,000 stones an hour; the X4 Pro Plus sets up to 15,000 across two stations.

Also called: diamond setting machine, stone setting machine, wax setter, CNC stone setting machine.

Station

One working position on a setting machine — one model being set at a time. A single-station machine sets a model, then stands idle while you change it over. A double-station machine lets you load the next model on one side while the other side is still setting, so the machine keeps working between batches instead of waiting for you.

See also: single vs double station.

Spot accuracy

How close the machine puts each stone to the position you programmed. Both Semsons Tech machines hold ±0.02 mm — about one fiftieth of a millimetre, finer than the eye can resolve. It shows up most in pavé, where a row of stones only looks right if every one of them sits on the same line.

Also called: placement accuracy, positioning accuracy, repeatability.

Five-axis motion

The setting head can move in five separate ways: three straight lines — left to right, front to back, up and down — plus two rotations. The two turns are what let the nozzle come at a stone position from an angle instead of only straight down, which is how a curved or domed surface gets set at all. The X4 Pro Plus rotates through 540°.

Also called: 5-axis, five-axis movement.

Wax model

The wax copy of the piece — injected, milled or 3D-printed — that the stones are set into. The metal is cast around the stones afterwards, so they end up held in the finished piece without anyone having to set them by hand into metal.

Also called: wax pattern, wax piece.

Sorting tray

A flat metal plate covered in a grid of small pockets. Stones are shaken across it until each one drops into a pocket table-up, ready for the nozzle to pick up. A standard tray has a 40 × 80 grid and holds 3,200 stones from 0.8 to 1.9 mm. Each tray is cut for one size band, because a pocket that fits a 1.0 mm stone will not seat a 2.5 mm one.

Also called: diamond sorting tray, stone tray, DSSMT tray. See the trays.

Deep-pocket grid

The tray pattern used for stones of 2.0 mm and above. A bigger stone needs a deeper pocket to sit flat and stay flat while the arm moves over it — a stone that tips is a stone the nozzle misses. Deeper pockets take up more room, so a deep-pocket tray holds 800 stones in a 20 × 40 grid rather than 3,200.

Wide-format tray

A longer tray that presents more stones per loading, so a long run is interrupted for refilling less often. Wide-format trays use a 30 × 85 grid holding 2,550 stones for 0.8 to 1.9 mm, and a 15 × 49 deep-pocket grid holding 735 for 2.0 to 3.0 mm.

Also called: DSSMT-01L, SSMWT tray.

Suction nozzle

The tip that picks a stone up with vacuum and releases it into the wax. Five nozzles cover the whole range from 0.8 to 3.0 mm — 502, 502B, 503, 503B and 504 — and each is matched to one size band. A nozzle is a wear part: when pickups start being missed, the nozzle is the first thing to change, not the machine.

Also called: pick-up nozzle, vacuum nozzle. Which one do I need?

Size band

The range of round-stone diameters that one nozzle and one tray are built for — 1.5 to 1.9 mm for the 503B, for example. Inside the band, pickup is reliable. Outside it, the stone either will not lift at all because the suction is too weak for it, or will not let go cleanly because it is too small for the tip.

Base with stud

A 76 mm metal disc with an upright pin, which holds the wax model in one fixed, repeatable position on the machine bed. Because the model always sits the same way round, the coordinates you programmed keep pointing at the same places on it. Replace the base when the face wears, when the pin is no longer square to it, or when corrosion sets in.

Also called: mounting base, wax mounting base. See the base.

Wax setting silicone

The putty that holds the wax model on its base through the run and peels off cleanly afterwards. SSMAB-01A and 01B are ready to use straight from the tub, with nothing to mix. AB silicone putty is a two-part version you knead together before use.

Also called: fixing putty, wax holding putty. Full guide.

Consumable

A part that wears out in normal running and is replaced on a schedule or on symptom: nozzles, silicone, trays and mounting bases. Nearly every stoppage in a setting room turns out to be a consumable rather than the machine itself, which is why the stocked ones go out the same day from Mumbai and Rajkot.

See also: consumables, spares and service.

Melee

Small round stones, generally under 2 mm, set in quantity as accent or pavé stones. Melee is what automatic setting exists for: the work is repetitive, the stones are too small to handle comfortably, and there can be several hundred of them in one piece.

Said: MEL-ee.

Pavé

A setting style where small stones sit so close together that the metal between them nearly disappears and the surface looks paved with stone. Micro-pavé uses stones of roughly 0.8 to 1.2 mm, which is the size range where setting by hand gets slowest and a machine gains the most.

Said: PAH-vay.

Table

The flat top facet of a cut stone — its largest face, the one you look straight down onto. “Table-up” means the stone is lying the right way round in its tray pocket, which is the only way round the nozzle can pick it up and set it.

CVD

Chemical vapour deposition — one of the two ways laboratory diamonds are grown, by building carbon up in layers out of a gas. A CVD stone runs through exactly the same trays and nozzles as a natural stone of the same diameter.

Also called: lab-grown diamond, CVD diamond.

HPHT

High pressure, high temperature — the other way laboratory diamonds are grown, by squeezing and heating carbon much as the earth does. Like CVD stones, HPHT stones set no differently from natural diamond of the same size.

Also called: lab-grown diamond, HPHT diamond.

CZ

Cubic zirconia, a man-made stone used widely in volume jewellery. To the setting machine it is simply a round stone: a 1.3 mm CZ uses the same tray and the same nozzle as a 1.3 mm diamond.

Also called: cubic zirconia, American diamond.

Ultrasonic cleaner

A tank of liquid vibrated tens of thousands of times a second, so that the liquid does the scrubbing and nothing solid ever touches the piece. The Semsons Tech ST4820 has a 2.3 L tank and runs at 40 kHz. An ultrasonic cleaner removes dirt, not tarnish.

See also: what size do I need?

Cavitation

The thing that actually does the cleaning. The vibration makes millions of microscopic bubbles form and collapse in the liquid, and each collapse fires a tiny jet at whatever is beside it. Because the bubbles go wherever the liquid goes, they reach the underside of a prong and the inside of a chain link — places no brush can get to.

Transducer

The part bonded to the floor of the tank that turns electricity into vibration. Larger tanks need more of them, so that the whole tank cleans evenly.

Frequency (kHz)

How many thousands of times a second the transducers shake the liquid. A lower frequency makes bigger, harder-hitting bubbles; a higher one is gentler and finer. 40 kHz is the usual setting for jewellery and gentler on stone settings; 28 kHz suits casting plaster and heavy polishing compound. A dual-frequency tank switches between the two.

SUS304

A common grade of stainless steel, often used for the tanks and baskets of ultrasonic cleaners because it resists corrosion from water and cleaning liquids. Ask the seller which grade a tank is made from.

Also called: 304 stainless, 18/8 stainless.

XRF

X-ray fluorescence — a way of reading what a metal is made of without harming it. The analyser shines X-rays at the piece; every metal inside it glows back at its own characteristic energy, and the instrument reads those energies as a list of percentages. Nothing is scratched, filed or dissolved. The Signet Si-Pin benchtop analyzer returns a result in 5 to 60 seconds.

Also called: XRF analyser, gold purity tester, karat tester.

Non-destructive testing

Any test that hands the item back exactly as it arrived. It matters in gold because the older methods do not: a touchstone test rubs metal off, and a fire assay consumes the sample altogether. XRF reads the piece and leaves it unmarked, so finished stock and a customer’s own jewellery can both be tested.

Also called: NDT, non-destructive assay.

Karat

Gold purity counted in twenty-fourths. 24K is pure gold, 22K is 22 parts gold to 2 parts other metal, 18K is 18 parts in 24. An XRF analyser reports the karat and the exact percentage together. Note that this is not the carat that weighs a stone — same sound, different measurement entirely.

Also written: K, kt, carat (of gold).

Hallmarking

The official mark certifying that a piece really is the purity it is sold as. In India it is administered under the Bureau of Indian Standards (BIS), and hallmarking centres are among the steadiest users of XRF testing.

Also called: BIS hallmarking.

Plating detection

Catching an item that is gold only on the outside, over a cheaper metal underneath. XRF reads to a depth of 15 to 20 microns, so it sees past a plated layer and flags the piece instead of reporting the surface as if it were solid.

Tungsten fill

A fake gold bar with a tungsten core. It is the hardest fake to catch by weighing, because tungsten is almost exactly as dense as gold, so the bar passes a density check. XRF reads composition rather than density, which is what gives it away.

Also called: tungsten-filled bar, salted bar.

Job work

Manufacturing carried out for another business, on their metal and to their designs. It is how a great many smaller units and karigar workshops operate. Job work usually means short runs that change often, which tends to favour a single-station machine over a double.

Karigar

The skilled craftsperson who makes jewellery by hand — the bench worker a workshop is built around. Automatic setting is not a replacement for one: it takes the repetitive melee off the bench so the skilled hand work stays where it belongs.

See also: automatic vs manual setting.

SEEPZ

The Santacruz Electronics Export Processing Zone in Mumbai — a customs-bonded special economic zone, and India’s largest cluster of modern studded-jewellery manufacturing. More than half the country’s studded jewellery exports come out of it.

See also: Semsons Tech in Mumbai and SEEPZ.

GJEPC

The Gem and Jewellery Export Promotion Council — the industry body under India’s Ministry of Commerce. It maps and supports the country’s manufacturing clusters and runs training institutes in Mumbai, Delhi, Surat, Jaipur, Varanasi and Udupi.

JMA

The Jewellers Manufacturers Association. Semsons Tech holds a JMA award.