The 4Cs: Cut

A Diamond’s Cut Unleashes Its Light

Diamonds are renowned for their ability to transmit light and sparkle so intensely. Cut quality is the factor that fuels a diamond’s fire, sparkle, and brilliance. Precise artistry and workmanship are required to fashion a stone, so its proportions, symmetry, and polish deliver the magnificent return of light only possible in a diamond. The final beauty and value of a particular diamond depend more on cut quality than anything else.  If the diamond is not well cut, it will not interact with light as it should.

The GIA Diamond Cut Grading System for standard round brilliants in the D-to-Z color range is based on the assessment of seven components. The first three are appearance-based aspects: Brightness (internal and external white light reflected from a diamond). Fire (the dispersion of white light into all the colors of the rainbow). Scintillation (the pattern of light and dark areas and the flashes of light, or sparkle, when a diamond is moved). The remaining four are related to a diamond's design and craftsmanship: Weight Ratio (the weight relative to the diameter). Durability (the girdle thickness). Polish (the finish of the facets). Symmetry (the variation of different parameters that define the proportions).

In GIA’s system, each component is assessed individually, taking into account the relative importance of that component in the overall cut quality of the diamond. The GIA cut scale contains 5 grades: Excellent - Very Good - Good - Fair - Poor.

A diamond’s cut and its shape are often confused. A diamond’s shape refers to the general silhouette of the stone, its outline when viewed face-up (round, oval, heart, ...). While a diamond’s cut refers to how well the arrangement of the facets interacts with light (excellent to poor).

This short video explains the GIA cut scale and how GIA classifies round brilliant cut diamonds with a cut grade ranging from Excellent to Poor by factoring in a range of parameters including the diamond’s proportions, culet size, girdle thickness, polish and symmetry descriptions.