Contact
Click below to speak to a Diamond Consultant or customer service.


or
Live Chat
8:00 am - 6:00 pm CST
Click below to speak to a Diamond Consultant or customer service.
or
Live Chat
8:00 am - 6:00 pm CST
Evaluating the combined effects of facet shapes and angles, girdle width, culet size, polish and symmetry on the overall appearance of a diamond is a daunting task, even for professional gemologists. Fortunately, all of these factors have already been taken into consideration when calculating the diamond's Cut grade.
Because Cut grade provides a single rating which weighs the combined impact of all of the factors listed above on a diamond's visual performance, it is a simple yet vital tool in evaluating a diamond.
Cut grade should be a primary consideration when evaluating a diamond. Only when comparing two diamonds of identical Cut grade should the individual components of Cut (such as girdle width, symmetry, polish, depth%, table %, and culet size) be used as further refinements or tie breakers.
Unlike the other "Cs" (carat weight, color, and clarity), the various Cut grades in existence today were not originated by GIA, and are not uniformly applied. In fact, GIA has only been assigning cut grades since 2005, and only to round diamonds.
Even though retailers use common terms to describe Cut (such as Excellent, Very Good, Fair, Poor) the terms are not uniformly defined or applied. In fact, a diamond seller may assign any cut grade they choose, based on any set of factors they wish. One retailer will use terms such as "Signature Ideal", "Ideal", and "Excellent"; while another uses "Ideal" to describe all three, and another uses "Excellent" for all. Be cautious when comparing cut grades from different sources, as they are most likely inconsistent.
To avoid confusion or misrepresentation of any diamond, Lumera uses the same cut grades as employed by GIA, and does not engage in "cut inflation" by creating other grades ("signature", "super ideal", etc.).
Also, be aware of diamond sellers who assign their own cut grades in place of what GIA has already assigned to a particular diamond. Many popular websites and retail stores display their own, more generous Cut rating, in place of the GIA grade.
At Lumera, the GIA cut grade is always shown. For diamonds without a GIA cut grade (because the diamond was certified before GIA began assigning cut grades in 2005, or is a shape that GIA does not currently assign cut grades to), Lumera will apply its own cut grade according to a proprietary formula. Like GIA, the Lumera cut grade is based on a variety of factors and is conservatively applied. In fact, when comparing our cut grade to that assigned by GIA, the Lumera grade is equal to or lower than GIA 90% of the time.
Cut grade is assigned by the GIA (or Lumera itself when there is no GIA grade), using the following scale:
Excellent |
Maximum fire and brilliance. Reflects nearly all of the light that enters the diamond, creating exceptional sparkle and life. |
Very Good |
Properly reflects most of the light that enters the diamond, producing superior fire and brilliance. Under normal lighting conditions, appears very similar to Excellent Cut, but for a lower price. |
Good |
Reflects a majority of the light that enters the diamond, for an above average appearance. An excellent value compared to higher cut grades. |
Fair |
Allows much of the light entering the diamond to escape from the sides or bottom, reducing perceived fire and brilliance. More acceptable in diamonds of less than .75 carats, where differences in sparkle are more difficult to perceive. |
Poor |
Allows most of the light entering the diamond to escape from the sides or bottom. The diamond may appear noticeably dull and lifeless, even to an untrained eye. Lumera does not offer Poor cut diamonds. |
Questions about cut or other aspects of a diamond? Ask a diamond consultant for answers. A consultant will answer any questions you have, and if you like, search for diamonds on your behalf that match your criteria. Chat online, or email consultant@lumeradiamonds.com.
Cut grade is the most important factor in determining the overall appearance of a diamond, because a poorly cut diamond will seem dull even with excellent clarity and color. Conversely, a well cut diamond can have a slightly lower color (G-H) or clarity (SI1-SI2) and still look quite beautiful, due to its superior ability to create sparkle and brilliance.
For superior brilliance, choose a diamond with a Cut grade of Very Good or Excellent for round diamonds, and Good or better in fancy shape diamonds. When choosing a diamond in this range, make sure its Symmetry and Polish are Very Good or Excellent, so that the impact of the above average Cut is not obscured.
For those on a budget, primarily concerned with size, a diamond of Fair - Good cut may be an acceptable choice, especially in fancy shapes. While the diamond will lack the scintillation and brilliance of a well cut diamond, it will allow a significant increase in size for the same price.
Avoid Poor cut diamonds, even if size is the primary concern. Most find these diamonds to be an unacceptable trade off, despite the lower price. Lumera does not offer Poor cut diamonds.
Visit the Lumera Diamond Buying Guide for additional tips and advice.