In June 2025, the Gemological Institute of America announced a fundamental shift in how they evaluate lab-grown diamonds, moving away from the traditional 4Cs system that's been the industry standard since the 1940s. The new Premium/Standard grading system launched on October 1, 2025, and represents a major change for anyone shopping for or owning GIA-certified lab diamonds.
What Actually Changed
GIA previously graded lab-grown diamonds using the same detailed system as natural diamonds, providing specific grades like "D colour" or "VVS1 clarity" along with comprehensive Cut, Colour, Clarity, and Carat analysis. Starting October 1, 2025, GIA replaced this approach with a simplified quality assessment that assigns lab diamonds to one of two categories—Premium or Standard—or provides no grade at all for stones that fail to meet minimum quality standards.
According to Tom Moses, GIA's Chief Laboratory Officer, the change reflects market reality: "More than 95% of laboratory-grown diamonds fall into a very narrow range of colour and clarity, so it's no longer relevant to use the nomenclature created for natural diamonds."
Why GIA Made This Change
Lab diamonds are manufactured in controlled environments using HPHT (High Pressure High Temperature) or CVD (Chemical Vapor Deposition) processes, which produce remarkably consistent results compared to natural diamonds formed over billions of years with massive geological variation. More than 95% of lab diamonds fall within D-H colour (colourless to near-colourless), with the majority achieving VS1 or better clarity due to controlled crystal growth.
As lab diamond prices dropped dramatically, the cost of detailed GIA certification often exceeded the value of smaller stones, making traditional grading economically impractical. The new system also creates clear market separation between natural and lab-grown diamonds, reinforcing that these are fundamentally different products with different value propositions.
The New Grading Categories Explained
Premium Category
To earn the Premium designation, lab diamonds must meet strict criteria across all quality factors. This means D colour, VVS clarity or higher, excellent polish and symmetry, and for round brilliant cuts, an excellent cut grade. Premium represents the highest quality classification available under the new system.
Standard Category
The Standard category covers a broader range of acceptable characteristics, including E-J colour, VS clarity, very good polish, and very good symmetry (or good for fancy shapes). Round brilliant cuts require a very good cut grade. Stones that combine any mix of Premium and Standard criteria receive the Standard designation.
No Grade
Lab diamonds that fail to meet the minimum Standard criteria receive no GIA assessment. These stones are returned to the submitter with a $5 evaluation fee, while graded diamonds cost $15 per carat with a $15 minimum fee. GIA only accepts stones of 0.15 carats and above for evaluation.
Every graded stone receives a printed quality assessment document and laser inscription on the girdle stating "Laboratory-Grown" along with a unique GIA assessment number.
Industry Reactions
The Natural Diamond Council welcomed the change enthusiastically, viewing it as bringing "greater market clarity" and reinforcing the fundamental differences between natural and lab-grown diamonds. Natural diamond advocates argue the move validates what they've long maintained—that natural and lab-grown diamonds shouldn't be evaluated using identical frameworks.
Lab diamond companies had mixed reactions, with some expressing concern that the simplified system diminishes their product's perceived value. Amish Shah from ALTR criticized the move as "repositioning after failing to dominate market share," suggesting GIA's shift reflects their minimal presence in the lab diamond grading market rather than genuine quality concerns. GIA currently grades fewer than 5% of lab-grown diamonds, with most consumers choosing IGI for more affordable certification services.
What This Means for Shoppers
If you're shopping for lab diamonds now, you'll encounter the new Premium/Standard system on all GIA reports issued after October 1, 2025. Traditional 4Cs grading for lab diamonds ended on September 30, 2025, though all previously issued reports remain valid and may even become more valuable over time as documentation of precise quality grades.
The new system simplifies decision-making by grouping lab diamonds into clear quality tiers, but it removes the detailed information many buyers value when comparing stones. If you want specific colour and clarity grades, consider certification from IGI (International Gemological Institute), GCAL, or HRD Antwerp, all of which continue using traditional 4Cs methodology for lab diamonds at significantly lower costs than GIA.
Regardless of which grading system or laboratory you choose, the fundamentals remain unchanged: buy from reputable sources, understand exactly what you're getting, and prioritize the diamond's actual beauty and performance over paperwork. Focus on cut quality above all else, ensure proper certification for authenticity, and remember that a well-cut Standard grade diamond often looks more brilliant than a poorly cut Premium stone.
Alternative Grading Options
IGI (International Gemological Institute) remains the dominant player in lab diamond grading and continues providing full 4Cs analysis including specific colour and clarity grades. IGI certification costs significantly less than GIA while maintaining strong market recognition and retail acceptance.
GCAL & HRD Antwerp also maintain traditional 4Cs methodology with detailed analysis and documentation, offering shoppers additional options for comprehensive grading reports that provide specific quality metrics rather than broad categories.
The shift reflects both the maturing lab diamond market and the technological realities of controlled diamond growth. While GIA's new approach may work perfectly fine for shoppers who trust broad quality categories, those wanting detailed specifications should explore alternative certification options that better match their needs.
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