Buying · Chapter 23

Verifying the stone, not just the paper

A real report and the right stone are two separate facts. How to confirm both before payment—and what to do when the record is old, hidden, or unfamiliar.

A report number that checks out proves that a report exists. It does not, by itself, prove that the diamond in front of you is the one it describes.

Two questions, not one

The first question is whether the report is genuine: does the issuing laboratory hold a record with this number, and does that record match the document you were shown? The second is whether this stone is the one on the report: do its weight, measurements, shape, and inscription agree with that record? An online report check answers the first. Only the stone—on a scale, under a loupe, or in a trusted jeweler’s hands—answers the second.

Worth remembering: Check the record, then check the stone against it.

Look the number up yourself

Type the laboratory’s address into the browser yourself rather than following a link or scanning a code supplied by the seller, then enter the report number. Compare every material line with the document and the listing: shape, carat weight, measurements, color, clarity, origin, growth method, treatment, and comments. A matching number with different measurements or grades is not a match. A PDF or printout can be edited; the laboratory’s own record is the reference.

Read the inscription, but don’t lean on it alone

Many graded diamonds carry a microscopic inscription on the girdle, usually the laboratory’s name or prefix and the report number, often with a laboratory-grown notation where it applies. It can be found under a 10× loupe with some patience, or quickly under a jeweler’s microscope. Ask to see it before the stone is set, while the whole girdle is accessible. An inscription can be polished away or added after grading, so it supports the match rather than proving it: weight and measurements still need to agree.

The picture on the report may not be your diamond

Some reports print a photograph or illustration labeled as a sample or representative image. It shows the shape and cutting style, not the particular stone, so a difference between that picture and the diamond is not in itself a warning sign. Read the caption beside any image. The clarity plot, where a report includes one, is drawn from the actual stone and is the more useful map for matching inclusions.

When the seller won’t share the report number

Some sellers hide or blur report numbers in their listings, often so that the same stone cannot be compared elsewhere. That is a commercial choice, but a buyer should still receive the number before paying—it is the only way to check the record independently. A seller who will not provide it until after payment is asking for trust the paperwork cannot yet support.

Worth remembering: No report number before payment means no independent check before payment.

In-house grades and unfamiliar laboratories

A document issued by the seller, or by a grading service the buyer cannot readily look up, is not an independent report. Grades from different laboratories are also not interchangeable, even when the words match. If a stone carries only an in-house or unfamiliar document, treat its grades as the seller’s description—or ask for the stone to be graded by an established independent laboratory before purchase.

Old reports, recut stones, and records that don’t appear online

A report describes the diamond as it was on the date it was graded. If a stone has since been recut, repaired, or chipped, its weight, measurements, and sometimes its grades have changed, and the old report no longer describes it; regrading produces a new report. Older reports may also be missing from a laboratory’s online lookup, or may have been superseded. Keep the original document, contact the laboratory directly with the number, and for an insurance claim or resale, ask a qualified appraiser to examine the stone and note whether it still matches the report.

Pressure is information too

Live auctions, direct messages, and countdown offers compress the time available for checking. A price far below comparable listings, reluctance to share the report number, and requests to pay by methods without buyer protection are each reasons to slow down, not to hurry. A seller confident in a stone can wait for it to be verified.

Three steps before you pay

First, look up the report number on the laboratory’s own website and confirm every material fact matches the listing and document. Second, confirm the stone itself: weight and measurements against the record, and the girdle inscription under magnification, before it is set. Third, get it in writing: an invoice naming the laboratory, report number, weight, and grades, with the inspection and return terms that apply.

Worth remembering: Record, stone, invoice—each should describe the same diamond.

Essential language

Report check: A laboratory’s own online lookup of the record held for a report number.
Girdle inscription: A microscopic laser marking on the diamond’s outer edge, usually a laboratory prefix and report number.
Representative image: An illustration of a shape or cutting style printed on a report; not a photograph of the specific stone.
In-house grading: Grades assigned by the seller or an affiliated service rather than an independent laboratory.
Recut: Re-polishing a diamond after grading, which changes its weight and measurements and can change its grades.

Questions to take with you

Did I look the report up on the laboratory’s site myself, and does every line match?
Do the stone’s weight and measurements agree with the laboratory’s record?
Have I seen the girdle inscription under magnification before setting?
Is the image on the report a photograph of this stone or a representative image?
Has the stone been recut or repaired since the report date?
Will the invoice name the laboratory, report number, and grades?