Guide to Diamond Cuts Part 1: Grading Scale, Quality, and Value

In a previous article, we talked about the 10 Best Diamond Shapes in the world, which include all-time favorites like the Tiffany Cut and Emerald Cut. However, your knowledge of that particular subject would be in vain if you know little about the cut, which is possibly the most important of the 4Cs (cut, clarity, color, and carat weight).

The Difference Between “Diamond Cut” and “Diamond Shape”

“Diamond Cut” refers to how skillful a lapidarist (gem cutter) cuts and polishes a diamond, as well as how well-proportioned the stone is, its overall symmetry and depth. Although often interchanged with “Diamond Shape,” Diamond Cut does not necessarily refer to the shape of the stone, such as a Round or Heart Shape.

Quality cut impacts a diamond’s brilliance and luminosity. If it’s well-cut, a diamond will glimmer and shine, reflecting a spectrum of stunning colors back to your eyes. Meanwhile, a poorly cut diamond appears dull rather than brilliant.

How the GIA Grades Diamond Cut Quality for Round Diamonds

The Gemological Institute of America’s (GIA) grades for round-shaped diamonds range from Excellent to Poor. Several factors are involved in the GIA’s process of grading diamond cuts, including brilliance, fire, symmetry, and polish. You should only consider round brilliant diamonds with an excellent cut, which provides the highest level of brilliance and fire. You should also ensure that the symmetry and polish of the gemstone are Excellent or Very Good.

GIA and AGS Diamond Cut Grade Chart

A certified gemologist at the GIA analyzes each diamond under magnification to pinpoint the cut grade, which could be:

  • Excellent. As mentioned, Excellent Cut Diamonds have the highest level of brilliance and fire. These diamonds dazzle with outstanding sparkle since almost all of the incoming light reflects on the flat facet or surface (table).
  • Very Good. Exceptional fire and brilliance are the main characteristics of a diamond with a Very Good Cut, with most of the entering light reflecting through the diamond’s table. Very Good diamonds have a similar radiance to those of Excellent grade, at least to the naked eye.
  • Good. Good Cut Diamonds feature brilliance and sparkle, with much of the entering light reflected through the table. These diamonds deliver beauty at a much lower price.
  • Fair. Fair Cut Diamonds provide little brilliance because entering light exits through the sides and bottom of the diamond. These diamonds can be a good choice for smaller-carat jewelry. They often act as side stones to a center gem with a higher grade.
  • Poor. Poor Cut Diamonds offer underwhelming brilliance, fire, or sparkle. Entering light immediately departs through the bottom and sides of the diamond.

The American Gem Society (AGS) diamond cut grade chart also includes an Ideal grade. When looking at AGS diamonds, they recommend Ideal Cut Diamonds, as not all Excellent Cut Diamonds have the best quality.

Not All Excellent Cut Diamonds Are Excellent

55 percent of all round diamonds receive an Excellent cut grade from the GIA, yet around 25 to 30 percent of them are not recommended. Jewelry consultants and appraisal specialists examine thousands of excellent-cut diamonds, only to find many bad specs. Therefore, even though it’s important to look at the diamond cut grade on the GIA certificate, you should also seek the opinion of other experts to avoid buying an excellent diamond that’s actually mediocre.

How Cut Grade Affects Price

The price of a diamond mostly depends on the overall quality and precision of the cut. For instance, the quality of this diamond is about as perfect it can get. In all angles, the diamond’s proportions are as exact as possible. As a result, you will pay a higher price for an Ideal Cut Diamond compared to one with an excellent cut.

If the facets of a diamond are beautifully proportional, for example, they refract and reflect entering light back to your eye in great fashion. The facets and pavilions of poorly-cut diamonds do not refract and reflect light as sublimely.

The amount of light reflected and brilliance found in most excellent- and ideal-cut diamonds are worth the additional cost. Fire and brilliance are the qualities that boost a diamond’s value and appeal. Those that are less radiant — no matter the table size or carat weight — may hold less merit.

In other words, the cut of a diamond is the trait that impacts its beauty the most. As such, if you have the money to splurge on diamond jewelry, pieces with higher diamond cut prices are worth every dollar. If you’re working with a tight budget, it may also be wise to forgo a GIA grade in clarity and color to ensure you’re choosing an ideal cut diamond.

Factors That Undercut the Price of a Diamond

Several elements are involved in determining Diamond Cut Quality. These include the proportions, facets, ability to capture and reflect light, and finishing touches on a diamond. The finer these elements are as a whole, the higher the quality and price of a diamond. And, although Color and Clarity also have substantial roles in a diamond’s worth, again, Cut is the most critical of the 4Cs.

Recap: What to Look for in a Diamond Based on Its Cut

Whether it’s for the love of your life or a gift for yourself, remember that these factors affect the price of a diamond:

  • Proportions (depth, width, table)
  • Facets (symmetry of the windows, mirrors, and steps of a diamond)
  • Fire (dispersion of colored light)
  • Brilliance (overall brightness of white light reflection)
  • Scintillation (the way a diamond sparkles when light moves)
  • Finishing details (treatment and polishing)

The team here at Biltmore Loan and Jewelry hopes that this article makes your search for a high-quality diamond easier, simple, and accurate. If you need further assistance in finding and choosing a diamond, keep an eye out for the second portion of this article, where we will be diving deeper into the qualities you should look for in a diamond cut.

Where to Sell Jewelry in Phoenix, AZ

If you have a collection or piece of jewelry that you’re ready to let go of, we are a reputable diamond jewelry buyer in Chandler and Scottsdale. Rest assured that our in-house GIA-certified specialist can determine the true value of your jewelry and offer a competitive price. Fill out this online appraisal form to get started.