Gemological Laboratory Center of Europe

Independent grading reports for diamonds and jewelry.

Independent grading reports for natural and laboratory-grown diamonds, colored gemstones and finished jewelry. Every report carries a unique number and QR code, verifiable online at any time.

Verify a report Our reports

The laboratory

We do not buy, sell or broker stones. We only examine them, so the report in your hand answers to one thing: the stone.

GLC works as an independent third party. Each piece is examined with professional laboratory equipment, and its characteristics are recorded as found at the time of evaluation.

3Report types

11Clarity grades, FL to I

D–ZColor scale

Every stone, under the loupe.

Our gemologists examine each piece by hand, under controlled lighting and 10× magnification, comparing color against reference stones before a single grade is written.

Reports

Three reports. One standard.

Choose the report that fits the piece. Each one is issued as a physical document and carries a unique number you can verify here.

Diamond Report

A full account of a loose or mounted diamond: carat weight, color, clarity and cut, measured against an international grading framework.

Natural, laboratory-grown (CVD / HPHT) or simulant
Carat, color, clarity and cut grade
Polish, symmetry and proportions
Fluorescence and measurements
Permanent treatments disclosed

Jewelry Report

For finished pieces. We document the metal, the mounting and every stone group, without taking the piece apart.

Metal type, color and purity (karat)
Jewelry weight in grams
Center stone and total carat weight
Graded "as mounting permits"
Photograph of the piece and estimated retail value

Gemstone Report

Identifies the species and variety of a colored stone, and records any treatment that examination can detect.

Species and variety
Natural, synthetic or simulant
Treatment detection and disclosure
Country of origin, when conclusive

Process

From your hands
to the record.

Seven stages, the same for every piece that passes through the laboratory.

Registration

Each piece is logged on arrival, photographed and given its own file, so its chain of custody is recorded from the first minute.

Identification

Every stone is screened to establish whether it is natural, laboratory-grown or a simulant, and whether it has been treated.

Weight & measurements

Precision electronic balances and gauges record the jewelry weight in grams and the stones' carat weight and dimensions.

Clarity & color

Inclusions and blemishes are assessed under 10× magnification; color is judged against reference stones under controlled lighting.

Cut & finish

Proportions, polish and symmetry are evaluated, together with the quality of the setting and the overall finish of the piece.

Report issued

Results are fixed into a numbered report with a photograph of the piece and printed on secured stock, or delivered as a digital report.

Online verification

The report number and QR code lead back to this site, where anyone can confirm the details at any time.

Education

The language of a diamond.

Carat, color, clarity and cut. Four characteristics that, together, describe how a diamond looks and what it is.

Carat

The unit of weight for gemstones. One carat equals 200 milligrams, or 0.2 grams.

Color

Graded by the absence of color, from D (colorless) to Z (light yellow or brown), under controlled light.

Clarity

How visible inclusions and blemishes are under 10× magnification, across eleven grades.

Cut

How well the proportions and finish return light to the eye as brilliance, fire and scintillation.

Inside a diamond

Point at the stone.

Move over the diamond, or tap a point, to see what a gemologist sees: the parts of the cut, and the characteristics that decide its clarity grade.

Tip: use Tab to move between the points.

Clarity scale

Graded under 10× magnification by a trained gemologist.

Color scale

Compared face-down against master stones, under controlled daylight-balanced light.

Report security

Built to be trusted.

A GLC report is protected on paper and online, so a buyer can always tell an authentic report from a copy.

Unique number

Every report carries its own number, issued once and never reused.

QR verification

Scanning the code opens the report's record on this site, with the photograph of the piece.

Secured stock

Hologram, security screen and microprint lines on every printed report.

Digital report

A complete digital copy of the report, ready to share or save as a PDF.

How to spot a fake report

Four checks, under a minute.

Scan the QR code.It must open a page on glc-lab.com. Any other address is not ours.
Compare the photo.The online report shows the photograph taken at the laboratory. It must match the piece in front of you.
Check every detail.Number, weight, metal and grades must match the paper exactly. A report marked cancelled or replaced is no longer valid.
Tilt the report.The hologram shifts as the paper moves. A photocopy stays flat.

Something doesn't match? Don't complete the purchase, and contact the laboratory.

Verify a report

Knowledge

Why a report matters.

Two stones can look alike and differ greatly in value. An independent report records what a stone is, how it was graded, and who stands behind the grading.

Natural or laboratory-grown?

Laboratory-grown diamonds share the physical and chemical properties of natural diamonds, so they cannot be told apart by eye. Every GLC report states clearly which one it is, and for laboratory-grown stones notes the growth method when known (CVD or HPHT).

What does "as mounting permits" mean?

When stones are set in metal, parts of them are hidden. We grade without taking the piece apart, so mounted stones are graded as far as the setting allows, and weights and grades are given as approximate.

Are treatments disclosed?

Yes. Permanent treatments detected during examination are noted in the comments. GLC does not issue reports for stones with non-permanent treatments.

How do I verify a report?

Enter the report number in the verification box on this page, or scan the QR code printed on the report. You will see the details recorded by the laboratory and the photograph of the piece.

What if I lose my report?

A replacement can be issued, but the piece must be brought back to the laboratory first, so we can confirm it is the same item.

Locations

Six countries. One standard.

LondonUnited Kingdom

New YorkUnited States

Tel AvivIsrael

DubaiUnited Arab Emirates

AntwerpBelgium

ParisFrance

Report check

Verify your report.

Enter the number printed on your GLC report, or scan its QR code.

About GLC

Independent by design.

GLC, the Gemological Laboratory Center of Europe, issues gemological evaluation reports based on examination with professional equipment. Our work is limited to evaluation. We take no part in the sale of the pieces we grade.

IIndependent third party, with no stake in any sale.

IIConsistent grading, recorded as found at the time of evaluation.

IIIEvery report numbered, and verifiable online.

Terms of the report

GLC is a gemological company that issues gemological evaluation certificates based on examinations conducted using advanced professional equipment. The certificate issued is a physical document. GLC is not obligated to have the certificate listed or available in the company’s online database or website. The gemological and monetary evaluation of the jewelry is determined at the sole discretion of GLC and constitutes an estimate only, based on the company’s internal standards and grading criteria. The stated diamond weights are approximate and provided as estimates only. GLC shall not be liable for any future claims, losses, or disputes arising from the use or reliance on the certificate. GLC acts as an independent third party and is not involved in the sale of the jewelry. Its role is solely to provide a gemological evaluation. In the event of loss of the certificate and issuance of a replacement, the jewelry must be resubmitted for verification to confirm that it is the same item.

Contact

Bring us the stone.

For fees, turnaround or a custom service, write to us. We reply on working days.

info@glc-lab.com

[Laboratory address]
[Phone] · [Opening hours]