The cut of a diamond (not to be confused with the shape of the diamond) is often viewed as the most important aspect to consider when looking for a piece of diamond jewellery. The cut has a significant impact on three qualities of the diamond: brilliance, fire and scintillation.
Too Deep Cut
Too Shallow Cut
Brilliance refers to the brightness of the diamond, created by reflected white light entering the diamond and exiting at the top.
When a diamond is moved, areas of contrasting light and dark can be seen that varies from facet to facet; this is known as scintillation.
Flashes of colour emitted by the diamond as a result of the dispersion of reflected white light. This is the rainbow-like flash often seen when a diamond is tilted.
These three factors are mainly affected by how shallow or deep a diamond is cut. For optimum brilliance, fire and scintillation, a diamond should be cut so that the reflected light exits purely from the top of the diamond. Diamonds that have been cut too deep or too shallow will lose light from the sides rather than the top, causing a huge loss in these three qualities.
An excellent cut diamond will produce the maximum amount of brilliance, fire and scintillation. Light will enter the diamond and reflect out of the top with a very small amount of light lost.
A diamond with a ‘very good’ cut will reflect most of the light that has entered it, producing a superior brilliance, fire, scintillation and overall sparkle.
A good cut diamond will reflect most of the light that enters the diamond, however it will produce less brilliance and fire than an excellent or very good cut diamond.
Fair cut refers to a diamond that lacks an optimum level of brilliance and fire caused by a significant loss of light from the bottom or side of the diamond rather than through the top as with better cuts.
A poor cut diamond will lose most of the entering light through the bottom or sides. It may appear dull and an obvious lack of sparkle will be observed.