Diamond Certification Guide
Last updated 17 October 2026
Quick answer
A diamond report records laboratory findings about the stone examined. Its fields depend on the service and issue date. Check the laboratory record, confirm that it belongs to the diamond offered, and assess appearance separately.
What is diamond certification?
Diamond certification is a common name for a laboratory grading report. GIA uses the term report rather than certificate. A report describes the stone examined and the findings covered by that service; check its title and date before comparing details.
A grading report supports comparison, but it is not a monetary valuation or a promise of resale value. GIA does not appraise stones. IGI lists appraisals as a separate US service, so an IGI grading report should not be read as an appraisal.
A report still needs context, though. Read it alongside the 4Cs of diamonds, and then judge the diamond itself through images, video or an in-person viewing wherever you can.
What is on a diamond grading report?
Report number
The number used to retrieve the laboratory record. A matching online result does not, by itself, identify the physical stone.
Shape and measurements
The outline, cutting style and millimetre dimensions, which help you understand face-up size.
Carat weight
The diamond weight, usually recorded to the hundredth of a carat.
Colour and clarity
Individual grades appear on applicable grading reports. Fancy-colour reports use different colour descriptions, while a GIA lab-grown Quality Assessment gives an overall category.
Cut, polish and symmetry
GIA gives an overall cut grade to standard round brilliant D-to-Z natural diamonds. IGI also offers optional fancy-shape cut grading. Polish and symmetry are separate finish assessments.
Fluorescence
Where recorded, this describes the response to ultraviolet light. Read the scale used on that report; the field is not shown on every assessment.
Origin
Check whether the report identifies natural or laboratory-grown origin. This does not itself establish a country of origin, mine or supply-chain history.
GIA vs IGI: which is better for diamonds?
GIA and IGI offer services for natural and laboratory-grown diamonds. The report title tells you which service was used; a loose-stone report and a jewellery report can cover different details. IGI explains its options in its own diamond reports overview.
On 1 October 2025, GIA introduced Premium and Standard classifications for its Laboratory-Grown Diamond Quality Assessment. The service covers eligible loose, colourless-to-near-colourless stones of at least 0.15 carats. GIA still assesses quality factors to determine the category; stones below the minimum criteria do not receive an assessment. Its coloured lab-grown report services are separate.
Compare reports with the same scope, then consider the actual stone, its appearance and its price. An overall quality category is not interchangeable with an individual colour or clarity grade. Ask how the seller has matched the diamond to the report as well as whether the report record has been checked.
| Factor | GIA | IGI |
|---|---|---|
| Services | Natural-diamond grading and separate laboratory-grown assessment and report services. | Natural and laboratory-grown diamond reports, plus jewellery reports. |
| Report fields | Read the report title and date: grading reports and quality assessments show different information. | Read the report type: assessments of mounted stones are limited by the setting. |
| Lab-grown diamonds | Premium or Standard for the eligible colourless-to-near-colourless Quality Assessment service; coloured-diamond reports are separate. | Individual colour and clarity grades on lab-grown grading reports; check the cut field for the shape and service. |
| How to use it | Check the online record, then arrange a physical match to the diamond when needed. | Check the online record, then arrange a physical match to the diamond when needed. |
How to verify a diamond certificate
- Find the report number on the document.
- Enter the number through the grading laboratory's report lookup tool, such as GIA Report Check or IGI Report Verification.
- Compare the online record with the document, including its date, measurements and reported results.
- Have a qualified professional check the physical match when needed, including identifying characteristics and any inscription. A copied inscription can match a genuine report number.
- Use photos, video or a viewing to judge appearance. These do not replace laboratory testing when the natural or laboratory-grown identity is in doubt.
Lab-grown diamond certification
There is no single format for every lab-grown report. IGI grading reports can show individual colour and clarity grades; the cut assessment depends on the shape and service. For a report on finished jewellery, the mounting can limit the available assessments. Read any qualifications and comments on the actual document.
An older report may use a different format. It records findings from the examination associated with that report, not a continuing check of the stone. Confirm the record and its match to the diamond. If condition or identity is uncertain, ask the laboratory about verification or re-evaluation rather than relying on the issue date alone.
The report should make the assessed laboratory-grown origin clear, but compare only the fields it actually provides. Our insights piece on how GIA changed lab-grown grading covers what it means for buyers in more detail.
If the origin question is still on your mind, read are lab-grown diamonds real?
Sources and further reading
- GIA: current laboratory-grown diamond services
- GIA: Quality Assessment introduced on 1 October 2025
- GIA: grading, certification and appraisal terminology
- GIA: report verification and counterfeit inscriptions
- GIA: how to read a diamond grading report
- IGI: laboratory-grown diamond reports
- IGI: round and optional fancy-shape cut grading
- IGI: report scope and service terms
- IGI: separate appraisal service
Frequently asked questions
- What is a diamond certificate?
- Buyers often use certificate to mean a laboratory grading report. It records the findings covered by the chosen service, such as identity, measurements and quality assessments. GIA calls its documents reports, not certificates. Read the title and date to understand the scope.
- What is a GIA certified diamond?
- The phrase usually means a diamond accompanied by a GIA report. GIA does not certify or appraise diamonds. Check the report type and online record, then confirm that the document belongs to the stone offered; the report number alone cannot establish that match.
- Is GIA or IGI better for lab-grown diamonds?
- Compare the information you need. IGI lab-grown grading reports provide individual colour and clarity grades. GIA uses Premium or Standard for its eligible colourless-to-near-colourless Quality Assessment service, with separate coloured-diamond reports. Check the actual report and stone rather than choosing on the laboratory name alone.
- Can a diamond certificate be faked?
- Yes. Documents can be copied or altered, and GIA has documented counterfeit laser inscriptions. Check the report through the official laboratory site. If the match is uncertain, have the physical diamond examined by a qualified professional or the laboratory; a matching number alone is insufficient.
- Do all engagement ring diamonds need certification?
- Ask what documentation is supplied for the centre stone and any accents. A report helps compare the characteristics it covers, but a jewellery report and an individual loose-diamond report are different services. Where stones are mounted, the setting can limit the assessment.
- Does a certificate guarantee a beautiful diamond?
- No. A report gives technical information, but it does not replace looking at cut quality, light performance, shape balance and how the diamond appears in the setting.
