Natural vs Lab-Grown Melee: How to Compare Parcels

Natural melee diamonds formed in nature; lab-grown melee diamonds were produced through a controlled growth process. Both are diamonds. GIA explains that laboratory-grown diamonds have essentially the same chemical, physical and optical properties as natural diamonds. They are different from diamond simulants such as cubic zirconia.

That similarity does not mean that two parcels have identical workmanship or appearance. A fair comparison still needs to address the individual stones and the consistency of the lot. Natural origin does not establish a tight size tolerance, and laboratory-grown origin does not establish flawless material or uniform cutting.

Melee refers to small diamonds commonly used as accents. GIA’s melee guide describes them as generally weighing below 0.20 carat, while noting that trade definitions vary. For an order, the actual dimensions and cutting style are more useful than the word “melee” alone.

For the broader origin comparison, read Uniglo’s lab-grown versus natural diamond guide.

Start with a common specification sheet. If one quotation is for full-cut rounds in a narrow diameter band and another is for a broader size mix, the price difference does not isolate the effect of origin.

Write “natural diamonds” or “laboratory-grown diamonds” clearly in the enquiry, purchase order and parcel label. If a piece uses different origins in different components, identify those components in the production record. A centre-stone report describes that stone; it does not establish the origin of the accompanying melee.

For lab-grown goods, ask for the declared growth method where available and relevant to your sourcing requirements. HPHT and CVD are growth methods, rather than parcel-quality grades. Uniglo’s CVD versus HPHT buying guide explains that distinction.

State any treatment requirements separately. HPHT can describe growth of a lab-grown diamond or treatment of an already existing diamond; those are different uses of the term. If the brief requires untreated natural melee, ask for evidence addressing that requirement as well as natural origin.

Keep supporting documents linked to the exact lot you purchase. A report for another shipment, a photograph of a machine or a general supplier statement is different from evidence about the parcel delivered to your workshop.

Appearance is not a dependable origin test. GIA’s identification guidance explains that traditional observations and instruments cannot reliably distinguish natural from lab-grown diamonds; advanced testing is needed.

Ask what screening or identification was performed, which stones it covered, and whether the method was suitable for their sizes, shapes and colours. Establish whether every stone was examined or a sample was checked. A quality sample is useful for evaluating a lot, but checking selected stones cannot establish the origin of all untested stones.

GIA’s Melee Analysis Service separates natural diamonds from laboratory-grown diamonds, simulants and potentially HPHT-treated natural material, within its submission criteria. Its service covers round and fancy-shaped melee. Confirm eligibility and available services with the laboratory for your particular goods.

A screening referral is a request for further investigation, rather than a final lab-grown identification. In a published GIA parcel examination, subsequent testing identified both natural and HPHT-grown diamonds among referred stones. Ask how referrals were resolved and what happened to stones outside the method’s operating criteria.

IGI’s screening protocol describes screening every diamond and returning natural diamonds in tamper-proof packaging labelled with the analysis date, seal number, result, weight and customer reference. If supplied with such documentation, match those identifiers to the package received.

Opening a package does not change the stones’ origin. It does make subsequent handling important: splitting, topping up or combining goods can break the connection between the original tested lot and the parcel now offered. Record those movements and arrange suitable checks before making an origin claim about a newly assembled lot.

Ask for the diameter band in millimetres for round melee. Where a sieve reference is used, confirm its millimetre mapping and the supplier’s permitted variation. Avoid assuming that an identical sieve label means identical sorting between suppliers.

For fancy shapes, request length, width and the variation permitted in each. Where fit requires it, add depth, girdle requirements and outline characteristics. A pear-shaped stone with the right length and width can still differ in shoulder shape or point placement from the stone used to develop the setting.

Agree the tolerance with the setter or production team. There is no single millimetre tolerance suitable for every pavé design, channel or fancy-shape setting. Record how measurements will be checked and how out-of-range stones will be handled.

Keep weight units clear. One carat equals 100 points; a 0.01-carat diamond weighs one point. Average stone weight can help estimate quantity, but it does not define diameter. If count matters, ask whether the stated quantity is measured or estimated, and verify that the unit is carats or points before calculating.

A colour or clarity range is a useful description, but it does not replace checking the distribution of goods within it. Ask whether a label represents a stated range, a minimum, a parcel assessment or individual grading. Establish who assigned it and under what procedure.

IGI’s diamond sorting service describes parcel colour and clarity ranges, with cut/finish and other parameters available on request. This illustrates why the scope of the supplied document matters. Uniglo’s diamond certificate guide provides background on laboratory documentation; for melee, read the specific parcel document and its coverage.

For a visual comparison, use clean stones on the same neutral background under the same lighting. Compare several groups from each lot. Look for stones that appear noticeably warmer, tinted, veiled, darker or less consistent with their neighbours. Ask a qualified reviewer to investigate persistent differences rather than attributing them to origin from a tray photograph.

A halo, a pair of earrings and a long tennis bracelet may require different matching decisions. Define the requirement against the finished design. If stones must match a centre diamond or an existing section of jewellery, provide that reference before ordering.

Establish whether the goods are single-cut, full-cut or a specified fancy cutting style. GIA describes single-cut round melee as having 17 or 18 facets and full-cut rounds as having 57 or 58. These are different products, so a quotation comparison should identify the style explicitly.

Ask what a seller’s “EX–VG” or similar finish description covers. Is it an internal sorting category, a parcel-level assessment or documented grading? Do not automatically interpret a commercial abbreviation as an individual laboratory cut grade for every stone.

Have the setter assess features relevant to production, including outline consistency, girdle variation and condition. Inspect a representative selection under magnification and view the goods together at the scale of the intended design. When a new specification is important, an agreed trial setting can help establish whether it works before placing a larger order.

Request dated quotations for the same specification, quantity and delivery basis. Record currency, quotation validity, testing charges, delivery costs and any sorting or return arrangements. This is more useful than applying a fixed “lab-grown discount” to every melee size and quality.

For production, distinguish the purchase weight from the quantity that passes your agreed checks. If unusually many stones need re-sorting, replacing or excluding from the job, the initial price per carat may give a misleading impression of value.

Cost per accepted stone = total attributable parcel cost ÷ number of stones accepted for the specified job.

The following example is invented to demonstrate the calculation. It is not a market quotation, an origin-price comparison or a typical rejection rate. It could be applied to competing natural parcels or competing lab-grown parcels.

Offer A has the lower purchase price per carat, while Offer B has the lower cost per stone accepted for this particular job. The accepted-stone percentages are 80% and 95% by count, not by weight. Account separately for supplier credits or any recoverable value of stones excluded from the job; rejection from one design does not necessarily make a stone unusable elsewhere.

Use a brief that both suppliers can answer. The acceptance process below is a proposed purchasing framework, rather than a laboratory grading standard.

Keep origin verification separate from any permitted quality variation. Agreeing an allowable proportion of dimensional outliers does not authorise undeclared origin mixing. Likewise, a parcel that passes origin testing still needs to meet the dimensional and appearance requirements ordered.

Before opening, photograph the label and any seal, and compare them with the invoice and screening documents. Record the lot number, weight and condition of the package. Keep natural and laboratory-grown goods clearly identified in separate storage and production records.

Inspect according to the quality plan agreed before purchase. Spread the selection across the parcel instead of choosing only the best-looking group. Record sample size, measurements and discrepancies. Sampling offers limited evidence about quality; use an agreed full inspection where the job requires it, and retain the separate origin-testing record.

Raise discrepancies within the agreed inspection period and before setting affected goods. Ask whether the supplier will replace outliers, re-sort the parcel, issue a credit or accept a return. Once you have accepted the lot, reserve appropriately matched spares if repairs or repeat production are anticipated.

For replenishment, recheck the new lot against the approved specification and retained reference. “Same supplier” and “same grade label” should not be the entire matching procedure for a later shipment.

Browse Uniglo’s natural and lab-grown melee diamond parcels, then send the origin, shape, cutting style, millimetre requirements and intended design when requesting a quotation. Ask for available parcel-specific documentation and clarify the inspection arrangements.

Contact Uniglo Diamonds with your specification to discuss suitable options. A complete brief makes the quotation easier to compare and gives your setter a clearer basis for assessing the goods.

• What Are Melee Diamonds? A Buying Guide for Jewellers
• Melee Diamond Size Chart: Sieve Sizes, Millimetres and Points
• Single-Cut vs Full-Cut Melee Diamonds