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GIA Explains the 4Cs
GIA 4Cs Interactive Sliders
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Diamond Education
Colour · Clarity · Cut · Carat Weight
Explore the four factors used to describe diamond quality: colour, clarity, cut and carat weight. Together, the 4Cs provide a consistent way to describe and compare a diamond’s characteristics, although no single grade tells the complete story of how a diamond will look.
Established in 1931, the Gemological Institute of America — better known as GIA — is an independent, non-profit institute specialising in gemmological research, education and laboratory services. GIA founder Robert M. Shipley introduced the concept of the 4Cs in the 1940s, creating a shared language for describing diamond quality. At John Macintyre & Son, we specialise in GIA-graded mined diamonds.
Please note: this interactive tool is provided by GIA and uses American English, including the spelling “color”. Throughout our own website, we use the UK spelling “colour”.
Interactive Guide
Compare the individual grades more closely with GIA’s interactive sliders, or learn how mined and lab-grown diamonds are formed, identified and graded.
Last reviewed: October 2026 · Interactive tool courtesy of GIA®.
