4Cs of Diamond Quality by GIA

The 26 D-Flawless diamonds of various shapes and sizes cut from the Lesotho Promise crystal. Courtesy: Graff

Once upon a time, there was no agreed-upon standard by which diamonds could be evaluated. Traders and jewelers used terms such as river or water to describe diamonds that were the most colorless, and Cape to describe pale yellow diamonds from South Africa’s Cape of Good Hope region. A diamond’s cut was described as “made well” or “made poorly.”

Then in the 1940s, Robert M. Shipley, the founder of GIA, coined the term 4Cs to help his students remember the four factors that characterize a faceted diamond: color, clarity, cut and carat weight. The concept was simple, but revolutionary.

His successor, President Richard T. Liddicoat, expanded his work by developing the now universally-utilized GIA D-to-Z Color Scale and GIA Clarity Scale for diamonds. He also established the scientific methods and procedures for objectively grading a diamond’s quality.

The creation of the Diamond 4Cs and the GIA International Diamond Grading System™ meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they are purchasing.

Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world. As the creator of the Diamond 4Cs and the International Diamond Grading System™, GIA is trusted by museums, auctions houses, and consumers all over the world to grade nature’s finest treasures.

Learn more about the history of the 4Cs.

Richard T. Liddicoat using a Diamond Scope in 1946. Photo: Leonard Charles & Associates, Inc.