Setting laboratory-grown diamonds at scale: why automatic wax setting pays off

Laboratory-grown diamonds are getting cheaper, and jewellery that uses more of them is growing. For a manufacturer that changes one thing above all: the number of stones in each piece, and so the number of stones your floor must set every hour. This guide covers what the 2026 market data shows, what you need to know about setting and casting laboratory-grown diamonds, and how automatic wax setting fits in.

Search engines and buyers say "lab-grown diamond". In this article we use the term in the BIS standard, laboratory-grown diamond, which is the one to put on your tags and invoices.

What the market data shows in 2026

• Prices are falling. JCK, citing Edahn Golan's wholesale price list, reported laboratory-grown diamond wholesale prices down 26% over 2025 and 13% year on year in Q2 2026.
• Indian export value fell while volume rose. GJEPC reported polished laboratory-grown diamond exports of US$1.13 billion in 2025-26, down 10.55% in dollar terms "even as volumes increased, indicating ongoing price correction".
• Jewellery set with them is growing. In the same release, GJEPC reported exports of gold jewellery studded with laboratory-grown diamonds up 31.30% to US$1,425.51 million.
• 2026 has started higher. Polished laboratory-grown diamond exports rose 17.08% to US$685.10 million in April to September 2026, according to GJEPC figures reported in October.

Cheaper stones let a designer put more of them into a piece at the same retail price. That is good for the buyer and for the manufacturer's sales, but it multiplies setting work.

Is a laboratory-grown diamond set like a natural one?

For the machine, yes. GIA explains that laboratory-grown diamonds have the same crystal structure as natural diamonds and nearly the same chemical, optical and physical properties. A setting machine does not know or care where a diamond came from. It cares about the stone's size, shape and consistency.

Whatever their origin, stones sorted into tight size bands feed a machine more evenly than mixed parcels, because each suction nozzle is made for one band of sizes.

Casting laboratory-grown diamonds in place: what to watch

Wax setting means the stones are set into the wax model and stay there through investing, burnout and casting. Diamond is the classic stone for this. The technical literature gives clear rules:

• Keep burnout cool enough. In a Santa Fe Symposium paper, Dr Ian McKeer recommends a top burnout temperature of 630 °C rather than 730 °C so diamonds do not burn, and notes that a burnt diamond has a frosted or milky surface. Follow your investment maker's stone-casting schedule.
• Use a stone-casting investment. Boric-acid-treated or special investments protect diamonds from oxidation during burnout, within limits. Note that a Rio Grande technical sheet warns boric acid is not recommended for cubic zirconia, as it can discolour it.
• Cool slowly. Quench only when the flask is cool. Rushing it can fracture stones.
• Keep stones small and clean. McKeer notes most stone-in-place casting uses stones up to about 2 mm. Avoid heavily included or fractured stones, and make sure stones do not touch, because the metal shrinks as it cools.
• Test every new lot first. The Rio Grande sheet advises comprehensive tests of stone suitability before production.

Two points specific to laboratory-grown stones

• Temporary colour change in some CVD stones. GIA's 2024 update reports that some CVD laboratory-grown diamonds change colour when heated, for example to 550 °C, and that these changes are temporary and fully reversible. Do not grade colour straight out of the flask.
• Treated colours are a risk. GIA says heating an irradiated diamond above 500 °C changes most blue-to-green colours. Keep treated fancy-colour stones, natural or laboratory-grown, out of stone-in-place casting.

We are not aware of any published study testing laboratory-grown diamonds specifically in stone-in-place casting. That is why the test cast is not optional.

Why automatic wax setting pays off with more stones per piece

When a piece carries forty stones instead of ten, hand setting becomes the slowest step in the factory, and skilled setters are hard to hire. An automatic wax setting machine picks each stone with a suction nozzle and places it in the wax model to ±0.02 mm.

Features that matter when pieces carry many stones of several sizes:

• Stone sizes from 0.8 to 3.0 mm. Five suction nozzle sizes cover 0.8–0.9, 1.0–1.2, 1.3–1.4, 1.5–1.9 and 2.0–3.0 mm stones.
• Large stone trays. Our diamond trays fit the X4 Pro Plus, Pro Mini and ST-HDSSM. The DSSMT-01 tray, for example, holds 3,200 stones of 0.8–1.2 mm, and the X4 Pro Plus's four trays hold 12,800 stones at a time.
• Several sizes or colours in one run. The X4 Pro Plus can set up to eight colours or sizes, or a mix of both, in one run.

Rated speeds are machine figures. Real output depends on your designs, stone sizes and wax quality, which is why we confirm a realistic figure against your own samples before quoting. See why wax quality decides setting output and how to choose a setting machine.

A production checklist for laboratory-grown diamond jewellery

1. Buy calibrated lots and record the supplier and growth method (CVD or HPHT) for each lot.
2. Test-cast every new lot in your own investment and burnout schedule before production.
3. Keep treated colour stones out of stone-in-place casting.
4. Check colour after the stones have rested under light, not straight out of the flask.
5. Use the full term, "laboratory-grown diamond", on tags, invoices and certificates.
6. Size setting capacity to stones per hour, not pieces per day.

Planning a laboratory-grown diamond line and want a setting figure based on your own designs? Send an enquiry or call +91 98216 12340.