Quality and Grading of Laboratory-Grown Diamonds
The fact that a diamond is laboratory-grown does not automatically reveal whether it is beautiful, well cut, free of visible inclusions, transparent, or desirable in the market. Origin and quality are different axes.
Laboratory-grown diamonds may differ in weight, dimensions, color, clarity, transparency, cut, polish, symmetry, and luminescence. In 2026, however, laboratories do not all describe these differences using the same reporting system.
Five Separate Questions
For a laboratory-grown product, it is useful to ask in sequence:
- Is the material diamond?
- Is its origin natural or laboratory-grown?
- If it is laboratory-grown, what is the growth method, and is there any post-growth treatment?
- What is the stone’s quality under the system of the particular laboratory?
- What is its market value in the specific channel and on the specific date?
A report may answer some of these questions, but not all of them.
The 4Cs as a Description of Properties
The carat is a unit of mass regardless of origin. Color, clarity, and cut geometry are also genuine observational or measurable properties of a laboratory-grown diamond. The 4Cs can therefore be applied conceptually to laboratory-grown material.
A particular laboratory may, however, choose to use a different nomenclature system. The most important modern example is GIA’s shift in 2025.
Factual Snapshot: GIA, August 8, 2026
Since October 1, 2025, GIA no longer issues a classic natural-diamond 4C grading report for loose colorless-to-near-colorless laboratory-grown diamonds weighing 0.15 ct and above. Instead, it uses a Laboratory-Grown Diamond Quality Assessment with an overall classification of Premium or Standard.
To qualify as Premium, all Premium criteria must be met: D-equivalent color, VVS or higher clarity, Excellent polish and symmetry, and Excellent cut for a standard round brilliant.
Standard encompasses a combination of Premium and Standard criteria down to defined minimums: E–J color-equivalent, VS clarity, Very Good polish, Very Good symmetry for round shapes or Very Good or Good for fancy shapes, and Very Good cut for a standard round brilliant.
If any criterion falls below the Standard threshold, the stone does not receive a GIA Quality Assessment classification. This is not the same as saying that it “is not diamond” or has no commercial value.
GIA currently offers a separate Laboratory-Grown Colored Diamond Report, which includes a full quality assessment, clarity plot, and an assessment of growth type and post-growth treatment for colored laboratory-grown diamonds. GIA’s D–Z and fancy-color services must therefore not be conflated.
An Older GIA Report Remains a Historical Document
Before October 2025, GIA used a different format and more traditional 4C nomenclature for laboratory-grown diamonds. An older report is not thereby “invalidated”; it remains a document of the results and methodology at the time it was issued.
When comparing an old and a new GIA document, it is therefore incorrect to automatically map one nomenclature onto the other.
IGI: A Separate Current System
IGI continues to issue a Laboratory Grown Diamond Report using the D–Z color scale, clarity categories from Flawless/Internally Flawless through Included, and cut information. It uses overall cut grading for round brilliants, while for fancy shapes it provides its own multicomponent approach incorporating finish, proportions, shape-specific requirements, and an assessment of light return.
IGI also states that the growth process and treatment can be recorded in the comments upon request. This is not the same as GIA’s Premium/Standard system, and no informal crosswalk should be constructed between them.
HRD Antwerp: The 4Cs Remain in Its Laboratory-Grown Report
HRD Antwerp currently states that it issues a separately labeled Laboratory Grown Diamond Grading Report for laboratory-grown diamonds, using the same basic 4C nomenclature as in its natural report. Laboratory-grown origin and the laser inscription are marked clearly.
This, too, is an institutional model, not proof that one universal industry report format exists.
GCAL by Sarine: Additional Focus on Measurement and Light Performance
GCAL by Sarine issues laboratory-grown certificates that may contain the 4Cs, growth method, and additional analyses of proportions, optical symmetry, and light performance. Its 8X concept is a proprietary system. Claims about its superiority, accuracy, or market distinction are treated in this book as company claims unless supported by independent evidence; the existence and description of the report product itself can be supported by the issuer’s official documentation. The system should not be mapped to GIA, IGI, or HRD grades as if the categories were identical.
ISO and CIBJO Are Not a Grading Crosswalk
ISO 24016:2020 concerns the grading of natural unmounted polished diamonds above 0.25 ct and must not be extended to laboratory-grown diamonds. Terminology documents such as ISO 18323 and the CIBJO Diamond Blue Book address nomenclature and disclosure, but they do not create one universal laboratory-grown grading report.
Growth Method, Treatment, and Quality Grade Are Not the Same Fields
CVD-grown, HPHT-grown, HPHT-treated, D-equivalent, VVS-equivalent, Premium, Standard, and Excellent describe different things. One stone may, for example, be CVD-grown, subsequently HPHT-treated, and of very high commercial quality. Another may be as-grown HPHT with weaker clarity or polish.
Quality must therefore not be inferred from the growth method.
Report, Inscription, and Physical Matching
A report number and QR code help locate the digital record. A laser inscription helps link the stone to the document. But an online record is not proof that the stone in hand is physically the same specimen.
Physical matching includes comparison of weight, dimensions, shape, inscription, clarity characteristics, and other relevant details. This applies to both natural and laboratory-grown products.
How to Compare Two Laboratory-Grown Diamonds
First, determine whether they belong to the same product and report category. Then compare weight and dimensions, color in the language of the specific report, clarity and transparency, cut in the same shape context, and polish and symmetry. Only then does it make sense to compare price.
If the report formats differ, do not assume that identically named or similar-sounding categories are fully equivalent.
Chapter Summary
- Laboratory-grown origin is not a quality grade.
- Carat, color, clarity, and geometry remain genuine properties of a laboratory-grown diamond.
- In 2026, laboratories do not use a single report system for laboratory-grown products.
- Since October 1, 2025, GIA has used Premium/Standard for applicable D–Z laboratory-grown diamonds.
- GIA’s colored laboratory-grown service is separate and retains a more detailed description of color and clarity.
- IGI continues to use detailed 4C nomenclature in its laboratory-grown report.
- HRD Antwerp currently uses a separately labeled laboratory-grown report with 4C nomenclature.
- GCAL by Sarine has proprietary quality and light-performance elements.
- Constructing an informal crosswalk among different laboratory systems is not professional.
- ISO 24016 must not be applied to laboratory-grown diamonds.
- Growth method, treatment status, and quality grade are separate pieces of information.
- A report and laser inscription help identification but do not replace physical matching of the stone.
[VISUAL 54.1: Five axes of laboratory-grown assessment—material, origin, growth/treatment, quality, and market value]
[VISUAL 54.2: GIA Quality Assessment since 10/1/2025—Premium, Standard, and below threshold]
[VISUAL 54.3: Institutional report models in 2026—GIA, IGI, HRD Antwerp, and GCAL by Sarine without an artificial crosswalk]
[VISUAL 54.4: Report verification versus physical matching—number, QR, inscription, weight, dimensions, and clarity characteristics]