Cut and Shape

Many people confuse the terms "cut" and "shape". The shape of a diamond is largely determined by the shape of the original uncut stone, whereas the cut of a diamond refers to its proportions, such as its depth and width ratio and the uniformity of its facets.  These characteristics seriously affect the brilliance, durability and other desirable properties of a diamond.

A good cut is essential to a diamond's beauty, because even a diamond with outstanding colour and clarity will not display the sparkle that diamonds are famous for if the quality of its cut is below standard. The main characteristics of a well-cut diamond are:

1. Width and Depth Ratio. The proportions of width and depth are very important for diamond brilliance, the reflection of white light that we see when we look at a diamond. Light traveling through a shallow cut diamond is lost out of the bottom of the stone. The lack of light play makes shallow cut diamonds appear lifeless. Light traveling through a diamond that's cut too deep escapes from the sides, darkening the stone. Light traveling through an ideal cut diamond is reflected back through the top of the stone, thus imparting maximum brilliance to the diamond.

2. Diamond Symmetry. "Symmetry" refers to the alignment of a diamond's facets, its flat and polished surfaces. The facets should be cut to achieve the best play of light. If the facets are misaligned, light will not bounce between them correctly, and the scintillation of the diamond is diminished. Diamonds graded Fair or Poor for symmetry usually have facets that are sufficiently misaligned as to affect scintillation.

3. Diamond Polish. The surface of the facets should be smooth and polished so that light can pass through them. If traces of polish are left on the facets, or if the facets have any roughness left on them, brilliance will be impaired to a greater of lesser degree.

To summarise, common problems with diamond cuts are: