Diamond Certification: A Complete Guide to Grading Reports
A diamond grading report is one of the most important documents you'll receive with a diamond purchase. This guide explains what certification is, what grading reports contain, how IGI and GIA compare for lab-grown diamonds, and what buyers should look for when evaluating a certified diamond.
What Is a Diamond Certification?
A diamond certification — more accurately called a diamond grading report — is an independent assessment of a diamond's characteristics, produced by a recognized gemological laboratory. It is not an appraisal of monetary value. It is a document that describes the stone's measurable physical attributes so that buyers, sellers, and insurers can reference a consistent, third-party evaluation.
Grading reports are issued by independent laboratories, not by the jeweler or retailer selling the stone. This independence is what gives the report credibility. Common issuing laboratories include the International Gemological Institute (IGI) and the Gemological Institute of America (GIA).
Why Diamond Certification Matters
A grading report provides objective documentation of a diamond's characteristics. Without one, you are relying entirely on the seller's description of the stone.
- Provides an objective, third-party assessment of the diamond's 4Cs
- Confirms whether the stone is natural or lab-grown
- For lab-grown diamonds, identifies the growth method (CVD or HPHT)
- Documents the laser inscription number for traceability
- Supports insurance appraisals and future resale
- Allows side-by-side comparison of different stones on consistent terms
Every EX3 Diamond is independently graded by IGI and laser-inscribed with its unique report number. We include the full grading report with every purchase.
What Is on a Diamond Grading Report?
A standard grading report from IGI or GIA will include:
- Report number — unique identifier, also laser-inscribed on the stone
- Shape and cutting style — e.g., Round Brilliant
- Measurements — diameter and depth in millimeters
- Carat weight
- Color grade — D through Z scale
- Clarity grade — FL through I3 scale
- Cut grade — for round brilliant diamonds: Excellent, Very Good, Good, Fair, Poor
- Polish and symmetry grades
- Fluorescence — none, faint, medium, strong, very strong
- Growth method — CVD or HPHT (lab-grown reports only)
- Clarity diagram — plotting inclusions and blemish locations
- Security features — hologram, barcode, QR code
IGI vs. GIA: Which Laboratory Is Better for Lab-Grown Diamonds?
Both IGI and GIA are internationally recognized gemological laboratories. For lab-grown diamonds specifically, IGI has become the industry standard.
| Feature | IGI | GIA |
|---|---|---|
| Grades lab-grown diamonds | Yes | Yes |
| Uses same 4Cs scale as natural diamonds | Yes | Yes |
| Discloses CVD or HPHT growth method | Yes | Yes |
| Industry standard for lab-grown | Yes — most widely used | Growing adoption |
| Turnaround time | Faster | Longer |
| Report verification | igi.org | gia.edu/report-check |
EX3 Diamond uses IGI grading because it is the most widely recognized certification for lab-grown diamonds among buyers and retailers worldwide. IGI reports are fully verifiable online and use the same grading standards as natural diamond reports.
How to Verify a Diamond Certificate
You can verify any IGI or GIA grading report directly on the laboratory's website using the report number printed on the document and inscribed on the stone.
- Locate the report number. It appears on the physical report document and is laser-inscribed on the girdle (outer edge) of the diamond, visible under 10x magnification.
- Visit the laboratory's verification website. For IGI reports, go to igi.org and use their report check tool. For GIA, visit gia.edu/report-check.
- Enter the report number. The laboratory database will display the grading information on record. Compare it to the physical report to confirm they match.
- Check the date. The report should be current and accurately describe the stone you are purchasing.
What to Look for in a Diamond Certificate
When reviewing any diamond certification, check for the following:
- Report issuer: Confirm it is from a recognized independent laboratory (IGI, GIA). Be cautious of in-house or retailer-issued certificates.
- Growth method disclosed: For lab-grown diamonds, the report should clearly state CVD or HPHT.
- Report number matches inscription: The number on the report should match the number laser-inscribed on the stone.
- 4Cs clearly stated: Color, Clarity, Cut (for round brilliant), and Carat weight should all appear.
- Verifiable online: You should be able to confirm the report on the laboratory's official website.
- Avoid reports without a laboratory name or address. Reputable laboratories are identified and contactable.
Frequently Asked Questions About Diamond Certification
Is a diamond certificate the same as an appraisal?
No. A grading report documents the diamond's physical characteristics. An appraisal assigns a monetary value based on market conditions and is typically provided by a jeweler or certified appraiser for insurance purposes. Both documents are useful, but they serve different purposes.
Can a diamond be recertified?
Yes. Diamonds can be submitted to a laboratory for a new grading report, though this is rarely necessary unless the stone has been significantly altered or the original report is lost.
What does it mean if a lab-grown diamond is certified?
A certified lab-grown diamond has been independently evaluated by a gemological laboratory using the same grading standards applied to natural diamonds. The report confirms the stone's 4Cs, discloses its growth method, and provides a verifiable record of its characteristics.
Do all EX3 Diamonds come with certification?
Yes. Every diamond sold by EX3 Diamond is certified by IGI. The grading report is included with your purchase and can be verified online using the report number.
Shop Certified Lab-Grown Diamonds
All EX3 Diamonds are independently graded and come with full IGI certification. Browse our selection of certified lab-grown diamonds — available in a range of carat weights, cuts, and grades.
