Gem grading is changing, and one of the most influential names in the industry is leading the shift. The Gemological Institute of America (GIA) has announced it will discontinue the use of its iconic 4Cs grading system—cut, colour, clarity, and carat—for lab-grown diamonds by the end of this year. Instead, these diamonds will be evaluated using a new descriptive model, categorizing stones as “premium,” “standard,” or ungraded if they fall below a certain threshold.
This marks more than a technical change, it’s a redefinition of how the diamond industry talks about value. GIA, a non-profit organization widely recognized as the authority in gemology, is making it clear that lab-grown and natural diamonds are not the same product and shouldn’t be measured by the same criteria.
Tom Moses, GIA Executive Vice President and Chief Laboratory and Research Officer, said, “More than 95% of lab-grown diamonds entering the market fall into a very narrow range of color and clarity. Because of that, it is no longer relevant for GIA to describe man-made diamonds using the nomenclature created for the continuum of color and clarity of natural diamonds.”
GIA’s move follows years of evolving terminology around lab-grown diamonds, including the earlier decision to move away from the word “synthetic.” But this new grading approach goes further, placing emphasis on the physical, emotional, and market distinctions between naturally formed and human-made diamonds.
Natural diamonds are shaped over billions of years beneath the Earth’s surface. They carry individual growth patterns, subtle flaws, and colors that make each one distinct. Their rarity, combined with their emotional and symbolic significance, has made them valued not just as jewellery but also as collectibles. For communities involved in responsible diamond mining, natural stones also continue to contribute to local economies and livelihoods.
Lab-grown diamonds, on the other hand, are manufactured using high-pressure high-temperature (HPHT) or chemical vapor deposition (CVD) techniques. They can be mass-produced and often appear near-identical in appearance, which limits their variation and, by extension, their value in terms of emotional meaning, investment, and scarcity.
By drawing a sharper line between the two, GIA is also addressing the language used by some lab-grown diamond marketers. Words like “sustainable” and “equivalency” have created confusion for consumers trying to understand what they’re buying. The new grading system is designed to cut through that noise and make room for clearer, more informed decision-making.
Removing the 4Cs from lab-grown diamonds is also about protecting consumer trust. The 4Cs were originally developed by GIA to help buyers understand natural diamonds. Using the same tool to describe factory-made stones, GIA believes, no longer serves today’s market.
Gemological labs across the world are expected to follow GIA’s lead once the change rolls out by the end of 2025. This shift is poised to reshape how diamonds are graded, marketed, and understood, clearly separating rarity from replication, emotion from manufacture, and long-held value from mass production.
