Education > Cut / Clarity / Color / Carat Weight / Certification / Conflict Diamonds

The C's : Cut

Cut is inarguably the most important of the 4 Cs in determining a diamond’s beauty to the naked eye. It is also the most difficult to understand.

At Continental Diamond we stock a wide selection of very well cut diamonds along with the finest cut diamonds in the world, Infinity Diamonds. These diamonds that fall into the world’s top percentile for cut can actually improve the appearance of the other Cs:

Even average cut quality makes a diamond flash and sparkle in bright lighting, though it will not enjoy benefits to the other Cs. Poor cut quality may look attractive under bright lights but in normal lighting can make a diamond appear small, tinted and lifeless.

Common Cut Standards

Despite its preeminent importance, cut is the least discussed C in most markets. You are probably wondering why that is. One main reason is that color and clarity grading are easily learned, but understanding light performance within diamonds requires some geometry and physics. While some professionals seek education (including several staff members at Continental Diamond), the vast majority of workday salespeople are not trained on cut and do not pursue the knowledge.

It’s worth noting that most diamonds are cut to average quality in order to save carat weight. In fact, in-depth discussions about cut would reveal that there is a lack of quality in average stores. The fact that many grading labs include little or no information about cut only underscores the resistance to cut education felt in commercial markets.

Cut Standards: AGS, GIA and EGL

The American Gem Society (AGS) and Gemological Institute of America (GIA) are the leaders at enforcing standards for cut performance (although neither grades cut precision).

The American Gem Society (AGS) boasts the only cut grading system recognized by the science community. Published by SPIE, the International Society for Optical Engineering, theirs is a diamond-specific metric which evaluates angular spectrum in three-dimensions and takes different distances from the light source and tilt into account. Less than 1 in 20 round diamonds are capable of earning the AGS Ideal grade and this number falls to 1 in 100 for princess cuts. Only 2% of diamonds are sent to the AGS for grading, so diamonds graded there are rare. AGS is currently the only lab that grades princess cut diamonds for cut.

The European Gemological Laboratory (EGL) and GIA cut grades employ a two-dimensional cut metric for round diamonds. Approximately the best 15% of round diamonds will earn the top grade in the GIA system.

Tip: The information on a lab certificate is a good place to start and will help you to narrow down your choices. At Continental Diamond we feel strongly that there is absolutely no substitute for seeing diamonds in front of you with your own eyes. This way you can determine which diamond best suites your personal taste.

One Step Further in Cut: Performance and Precision

The cut grades issued by the AGS, GIA and EGL grade cut performance, but not cut precision. Here are simple explanations for both to help you further understand diamond cuts:

Cut Performance

This is how efficiently light gets in and out of a diamond. The components of performance are:

The benefit of Ideal cut is maximized light return for higher values in all these categories. Performance has been judged in diamonds for many years. The level of performance, particularly brightness and contrast, can be seen in the AGS ASET® and its predecessor the Ideal-Scope®.

Round Brilliant Examples in ASET® and Ideal-Scope®

Cut Precision

This is how well the diamond’s facets (mirrors) align with each other in 3-Dimensions. Precision components include:

Optical Symmetry - uniformity of patterning, such as the "Hearts & Arrows" pattern seen in precise round brilliants

Degree of crispness of those patterns

The benefits of high precision cut are increased contrast values, purer spectral colors during scintillation and improved performance in low-light conditions.

Precision is a young aspect of cut that became possible in the 1980s and 1990s in rounds - and is only now surfacing in fancy shapes. Achieving top precision requires the most modern tools, extra time and higher skill sets to accomplish. The level of precision can be seen by using an Optical Symmetry or "Hearts & Arrows" viewer.

Round Brilliant Examples in Optical Symmetry Viewer

For more information on ASET® and Ideal-Scope® see our Cut Performance Tutorial
For more information on "Hearts & Arrows" Optical Symmetry see our Cut Precision Tutorial

Super Ideal Cut Diamonds: Top Performance and Precision

Only a fraction of the world’s diamonds have both top performance and top precision; they are rare enough that most people have never even seen one. Such diamonds actually improve the appearance of the other Cs, which makes cut the most important characteristic of your diamond. It is critical to remember that labs do not judge both aspects of cut: a diamond can have great performance without enjoying the benefits of precision. Others can be very precisely cut without the benefits of top performance.

Interesting Fact: At Continental Diamond we hand select each diamond that we sell for its fine quality and exceptional value. We are extremely proud of our selection of Super Ideal cut Infinity Diamonds which we believe are the market leaders in cutting round brilliant and princess diamond that display unmatched beauty. We import these diamonds directly from the cutter in Antwerp to ensure that you are receiving the most beautiful diamond at the best value. Interesting Fact: A true Super Ideal cut Diamond is rarer than a common cut diamond with a grade of D in color and Flawless clarity.