Certified vs Uncertified Loose Stones: The mm Test
Most loose stones sold in the trade have no certificate at all, and that is not a red flag — it is how the market for small stones works. What decides whether a stone is usable is a measurement, and you can take it yourself in under a minute.
What melee is, and why it has no papers
Melee is the trade word for small cut stones, roughly anything under 2.5 mm or under about 0.10 ct. They are the stones in a halo, a pavé band, a tennis bracelet, around a bezel.
At that size, individual documentation is impossible. A laboratory report costs a fixed amount per stone regardless of size; on a 1.5 mm stone worth a few dollars, the report would cost more than the stone. So the trade does not issue one. Melee moves in parcels — small paper packets, sealed and weighed — sold on weight and size.
How small stones are actually sold
Weight. A parcel is sold by carat weight, often in lots of a carat or more, with a stated stone count. Forty stones at 0.01 ct is 0.40 ct.
Sieve size. Melee is sorted through plates with round holes, producing standard bands — 1.20–1.40 mm, 1.40–1.60 mm and so on. A parcel marked 1.30–1.40 means every stone passed through the 1.40 hole and none through the 1.30. That band is the specification, and it is more precise than carat weight, because a parcel averaging 0.012 ct can contain stones from 0.008 to 0.018 and still hit the average.
The mm test
Here is what a certificate would not tell you, even if you had one: whether the stone fits.
Settings are machined to accept a specific diameter. A 1.5 mm seat takes a 1.5 mm stone; a 1.7 mm stone will not go in, and a 1.3 mm stone rattles and loses a prong within a month. When you buy a parcel for a repair or a custom piece, the question is never "is this good quality" — at this size everything is eye-clean and the colour is uniform — it is "is this the size the seat was cut for".
Millimetres are the specification; the certificate is not. A document reading "0.015 ct, VS, G" says nothing about fit.
Where a tenth of a millimetre shows
At melee scale small differences are visible, because they are relative. Going from 1.3 mm to 1.5 mm is a fifteen per cent increase in diameter and about a third more face area; the eye reads that as a different stone.
| Diameter | Typical use | What 0.1 mm does |
| 1.0–1.2 mm | Micro-pavé, delicate bands | Barely visible; prong coverage suffers |
| 1.3–1.5 mm | Standard pavé, halos | Seat will not take it, or sits loose |
| 1.6–1.8 mm | Halo surrounds, channel sets | Visible step in a graduated row |
| 2.0–2.5 mm | Side stones, three-stone shoulders | Breaks symmetry against its pair |
| Above 3 mm | Centre stones, single-stone pieces | Noticeable; worth documenting |
What tolerance is normal
A parcel sold as 1.30–1.40 mm contains stones across that band, and a good supplier sorts tightly inside it. Expect plus or minus 0.05 mm on individual stones in a well-graded parcel, up to 0.1 mm in cheaper goods. If you are setting a row flush, buy from a single parcel and set in order rather than mixing parcels — that is how the trade avoids visible steps.
For a matched pair, buy more than you need. Two stones ordered as 1.5 mm may differ by 0.08 mm and look wrong together; ten lets you pick a pair matching within 0.02 mm.
When you must have a report
Three situations, all about value rather than quality. A centre stone above roughly half a carat — at that size the stone is a significant share of the piece's cost and the report is a small percentage of the price. The piece is being insured or appraised — a report from an issuer the insurer recognises carries more weight than a seller's invoice. You are buying at a distance — if you cannot hold the stone, an independent document is the only substitute for your own eyes, though it still describes grades rather than cut quality.
When paperwork is wasted money
For melee, and for any stone under a couple of hundred dollars, a certificate is usually the wrong purchase. It does not improve the stone or change the fit, and it adds cost better spent on a larger stone or a better setting. What you need instead is a supplier who states the size band, holds to it, and supplies replacements from the same lot six months later when a stone is lost.
What to send a jeweller instead
Four lines, and they solve the problem a certificate was supposed to solve: diameter in millimetres with the tolerance you will accept, shape and cut, quantity, and the colour and clarity you need. If the reply comes back in millimetres rather than carats, you are dealing with someone who understands the job.
What we make
We cut stones in our own factory in Wuzhou, Guangxi, and have since 2008 — including melee, supplied by millimetre band rather than by certificate, because that is the measurement a setting needs. Single moissanite stones ship with a GRA card, and lab-grown diamond with an IGI report where the size justifies one.
Finished pieces run from $17 to $2,020, most around $98, set in 925 silver and 9K, 14K or 18K gold, with lab-grown emerald, ruby and sapphire alongside the diamond and moissanite. Shipping is free over $99 and $5.99 below it, and unworn pieces in original packaging can come back within 30 days.
