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History of the 4 C's

Diamonds have long been celebrated around the world as one of the finest, most beautiful natural wonders. Like so many precious and valuable items, diamonds require a universal method by which their value is determined. In the mid 20th century, the Gemological Institute of America (GIA) developed the 4 C’s to allow trained jewelers to grade the quality of diamonds and communicate that to buyers. At Adlers Jewelers, we use this grading system to assist our customers in choosing the best diamonds for them.


Diamonds naturally come in a variety of shades, from transparent to a yellow-ish brown. The less color found in a diamond, the more valuable it is. A diamond’s color grade is denoted on a scale from D, colorless, to Z, light yellow or brown. Completely colorless diamonds are very rare; most diamonds used in jewelry fall into the “nearly colorless” category. At the GIA lab, a master set of diamonds was established for each letter on the scale to ensure uniform grading. 


A diamond’s clarity is determined by the amount of inclusions present. Inclusions are naturally occurring byproducts of the jewel’s formation and actually help professionals to separate naturally formed diamonds from lab grown ones. The GIA’s clarity scale consists of 11 grades, from flawless to I3. Flawless diamonds’ inclusions can only be seen at a high level of magnification, while I3 diamonds’ inclusions can be seen by the naked eye. Flawless diamonds are more uncommon and thus much more valuable.


The cut refers to the way a diamond is shaped, given various facets that allow the stone to uniquely reflect light. There are many different cuts used in jewelry. A diamond’s proportions directly affect how it sparkles and its overall aesthetic. The GIA’s cut scale has five grades ranging from excellent to poor and is used for round cut diamonds. The cut grade is determined by a range of factors, evaluated by specialized technology.

Carat Weight

The last C stands for carat weight. One carat is equivalent to 200mg or one fifth of a gram. If all other Cs are equal in value, a one carat stone would be more valuable than four quarter carat stones put together. But, all factors on the grading scale must be considered to determine a diamond’s value, which means that bigger is not always better.

How to Read a GIA Diamond Report

A GIA diamond report is more than a simple grade. It is an accurate, unbiased, scientific profile of your gem. Each diamond is given a unique report number, which you can use to look up your gem online. This report provides in-depth information on each of the 4 C’s, ensuring you clearly understand your gem’s overall grade. An evaluation of the gem’s fluorescence is also given as an additional description of the gem’s unique characteristics. An asterisk next to a grade indicates that a treatment has been used to alter the color or clarity of the gem. The treatment used will also be detailed in the report.

Trust Adlers Jewelers for Incredible Diamonds

Our customers at Adlers Jewelers can browse a range of exquisite diamonds, choosing just the right gem whose characteristics match your particular preferences and budget. Our Westfield jewelry store is stocked with loose diamonds and diamond jewelry that will be cherished for a long time. Request an appointment today for a personalized consultation with one of our team members, or browse our inventory online.