Most years, we host our Bench Jeweler Workshop in March, attracting jewelers from around the country. We all look forward to the unique opportunity to visit with our customers. Last year, we couldn’t hold it and this year it's a bit delayed, so we thought we’d focus on it by highlighting some of the most popular classes this month.

Taught by our diamond grading experts, our Basic Diamond Grading class fills up quickly. It includes the basic grading elements with participants using live product in the correct grading environment. Our grading experts provide guidance on determining diamond’s 4Cs (carat, clarity, cut, and color), cover common and unique inclusions, and explain how labs perform grading.

Participants learn how to use a loupe, tweezers, and other essential instruments, making this perfect for new jewelers and students. We can’t duplicate the Bench Jeweler Workshop experience here, but we can present the general concepts about diamonds.

A Word About Lab-Grown Diamonds

Blue Lab Grown Melee Diamond

blue LG diamond

Princess-Shape Lab Grown Melee Diamond

princess LG diamond

Pink Lab Grown Melee Diamond

pink LG diamonds

As LGDs grow more popular, it becomes increasingly important to stay informed. This class doesn’t specifically cover LGD grading, but since they are chemically, optically, and physically identical to natural diamonds, they are graded on the same 4Cs. In 2020, we saw an indication of their importance, with GIA® now grading them and issuing reports. The primary issue remains complete transparency with your customers. A customer must know that is what they are buying.

Anatomy of a Diamond

It all begins with knowing the parts of a diamond, as shown below. Diamonds come in many shapes: round, oval, square (Princess), emerald (octagon that is step-cut or radiant cut), antique cushion, cushion, Asscher, pear, marquise, and baguette — straight or tapered. This diagram features a round diamond, the most popular shape.

anatomy of a diamond

The 4Cs

Diamonds are graded and priced according to the 4Cs, a universal grading system developed by the Gemological Institute of America (GIA®) and recognized globally. What are the 4Cs? They stand for Carat, Clarity, Cut, and Color.

This refers to a diamond’s weight — not size, despite popular misconception. One carat equals 0.2 grams (200 milligrams), although you can also refer to diamond weight in points. One carat is 100 points, so a 75-point diamond is equal to 0.75 carats. If all other factors are equal, larger diamonds have a greater value than smaller diamonds.

Carat (CT) to Millimeter (mm) Size Reference


This refers to the presence of inclusions in a diamond. Inclusions are typically viewed with a loupe at 10X magnification, though you can see some without using a loupe. We rank inclusions on a scale of F (flawless) to I (included).


This refers to a diamond’s exact proportions and the size and arrangement of the facets. A diamond’s cut grade is an objective measure of the diamond’s light performance — or the amount of sparkle it has. Diamonds with fine proportions, symmetry, and polish optimize their interaction with light and display the best brilliance, light dispersion, and scintillation.


This refers to the extent to which a diamond is colorless. We grade on a scale of D (colorless) to Z (light yellow), and an expert determines a diamond's color by comparing the stone to a master color set. When diamonds form with traces of other minerals, rare "fancy" colors result.


Grading Labs

Numerous diamond grading labs exist, with some reports more valuable than others. GIA® has earned international esteem for following the most rigorous standards and issuing the most reliable grading reports. For example, one lab may grade a diamond's color F, while GIA may grade it G — the difference between a colorless and a near-colorless stone. Below, you'll see an image of a GIA® Grading Report.


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