breaking down GIA's 4C's

As with any industry - the jargon can be intimidating. First time buyers may not know the meaning of the words used by overly zealous salespersons intent on making a sale. So, as an aluma of the Geological Institute of America’s Graduate Diamond program, I’m going to break down what exactly the 4C’s are and how you can use them to make informed purchasing decisions.

But first - some relevant history!

Until the middle of the twentieth century, there was no agreed-upon standard to judge diamonds until GIA founder Robert M. Shipley, a former retail jeweler, set out to standardize and professionalize the American jewelry industry. Through GIA, he and his team created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut and Carat Weight – the factors that, when combined, define a diamond's quality and ultimately determine its value. 

Before the International Diamond Grading System™, diamond merchants used inconsistent terms to describe diamonds. For example, terms like river or water were used to describe near colorless diamonds while clarity was described broadly as being “without flaws” or “with imperfections.” Unsurprisingly, it was difficult for jewelers to accurately communicate the characteristics of diamonds to potential buyers. 


First off - the only of the 4c’s that was already clearly defined before was carat, which had been consistently used to describe weight since the 1500s. 1 carat = 0.2 grams. 

So let’s get into the 3 remaining C’s. 



GIA Color Scale



GIA Clarity Scale


GIA Cut Scale