Wholesale Lab-Grown Melee and Calibrated Small Diamonds: A Buyer’s Guide

A workshop sets 60 stones of 1.30 mm into an eternity band. The parcel was sold as 1.30 mm, but a gauge shows stones from 1.26 to 1.35 mm. The setter files seats wider for some and packs metal around others, the band takes an extra day, and in daylight two stones look whiter than their neighbors. Each stone was a lab-grown diamond of the right grade. The parcel was not calibrated tightly enough for the setting.

Melee are small diamonds, usually under about 0.20 ct, used in pavé, halos, bands, tennis bracelets and accents. For manufacturing, the questions are size within tolerance, a narrow color and clarity range, consistent make, and confidence that every stone in the parcel is what it is sold as. Buy by millimeter size or sieve range, agree tolerances and quality ranges in writing, and ask how the parcel is sorted, screened and documented.

What to put in a melee order

Sizes: millimeters, sieves and weight

Swipe the table to see more →

Weights are approximate for well-cut rounds. Sieving groups stones by passing them through plates with set hole sizes, so a sieve range always holds some spread. Calibrated stones are measured more precisely. Channel, invisible, line and eternity settings need calibrated sizes; scattered pavé can often use a sieve range.

Swipe the table to see more →

Fancy-shape melee needs closer outline matching than rounds. Ask for a reference sample per shape and size.

Color, clarity and make

Melee is sold in ranges, not single grades. Agree the range in writing and keep a reference sample from the approved lot. Tighter ranges cost more but look more even in finished jewelry. Brilliant-cut melee hides small inclusions well; step-cut baguettes and carrés show more, so aim a clarity band higher for them.

Poorly cut melee looks dull or dark beside well-cut stones, and the difference shows most in a halo, where small stones sit next to a bright center stone. Check a sample under magnification for symmetry, polish and girdle thickness.

How parcels are sorted

Polished melee is sorted by size, by sieve or by measurement, then by color and clarity range under consistent lighting, and checked for make. Calibrated stones are measured one by one or on automated equipment. Ask how sorting is done for your order and how gauges and machines are checked.

Mixing and screening

Small stones rarely have individual reports, so the parcel description is all the buyer has. A lab-grown parcel should contain only lab-grown diamonds, with no simulants, and a natural parcel no lab-grown stones.

Screening devices range from handheld testers to automated machines that handle large numbers of melee. A 2024 GIA review notes that most screening devices give only a “pass” or “refer” result, and that some have wrongly passed simulants. A “refer” result means the stone needs laboratory testing, not that it is natural or lab-grown. Ask:

1. Is the parcel screened, and with which device or service?
2. What happens to referred stones?
3. Can the screening be stated on the invoice or parcel sheet?

Growth method and treatment

Much lab-grown melee is HPHT-grown, in line with China’s production, which is mostly HPHT. If your program requires as-grown stones or a specific growth method, state it in the order and get it confirmed in writing, because parcel documents do not show it unless asked.

Documentation and checks on delivery

For melee, documentation is usually at parcel level: total weight, stone count or size, shape, color and clarity range, laboratory-grown origin, and growth method or treatment status where stated.

On delivery:

• Check size distribution with a gauge or sieves.
• Compare color against a master set or the reference sample.
• Check a sample under magnification for clarity and make.
• Screen for origin if your program requires it.
• Record results against the agreed tolerances before stones go to the setter.

Melee is priced per carat for a given size, quality range and tolerance. Tighter tolerances, narrower color ranges and fancy shapes cost more, so compare quotes on the same specification.

Melee questions

Written byKai Chen

Sales & Technical Director, NUVU

11+ years supporting global clients with lab-grown diamond product consultation and market analysis.

Credentials: GIA Graduate Diamonds (GD)

About NUVU. NUVU is the international brand of New Perspective Superhard Materials Co., Ltd. in Zhecheng, Henan, China. We grow HPHT lab-grown diamonds in-house and cut, polish and match stones in our own workshop.