It is a common misconception that when talking about a diamond’s cut, we’re talking about its shape (eg. round, heart, pear, etc). Cut actually refers to how well a diamond’s facets interact with light to create sparkle and brilliance.

Of all the 4C’s, a diamond’s cut is the most complex and has the greatest impact on its …

• Brightness: The amount of internal and external white light that is reflected from the diamond
• Fire: The scattering of white light into a broad range of colours
• Scintillation: The amount of sparkle a diamond produces and pattern of light vs. dark areas resulting from reflections within the diamond

A well-cut diamond also reflects the design and craftsmanship that went into producing the diamond. It includes features such as the diamond’s weight to diameter ratio, girdle thickness, symmetry of its facet arrangement and quality of polish on all its facets.

In simple terms, the cut grade of a diamond refers to its light performance, meaning the degree to which the diamond retains and reflects the light that enters it. A diamond with a good cut will be highly reflective and exhibit the best possible amount of sparkle. Conversely, diamonds that ‘leak’ light through the bottom or side are usually cut too shallow or deep, and will thus have a less favorable cut grade.

Hence, it is the cut of a diamond that affects the way light travels through the gem, how much is reflected in the eye and how much leaks out the back.

A well-cut diamond gives off more bright sparkle and shine, therefore being more highly valued. A diamond that is cut poorly or too thin will have a lot of light leakage, eliminating its potential for sparkle, and diminishing its value. It takes great skill and craftsmanship to transform a diamond in the rough into a dazzling gem.

The Gemological Institute of America (GIA) have created an objective rating system that is widely-accepted as the standard for evaluating a diamond’s cut (in addition to the other qualities of the 4C’s).