Cut
The final criteria buyers use in determining the quality of a diamond is its
cut. The cut is the shape and proportion of the stone, as determined during
the diamond-cutting procedure. Round brilliant diamonds are cut with 58 facets.
A good cut has more sparkle or scintillation. The shape of the diamond, however,
is largely a matter of personal preference and does little to affect the
value. It is the work of the diamond polisher to allow the diamond to be
cut in such a way as to permit the maximum amount of light to be reflected
through the diamond. It is the cut that enables a diamond to make best use
of the light.

1. When a diamond
is cut with good proportions (an ideal cut), light is reflected from
one facet to another and then dispersed through the top of the stone.
2. If the cut of the diamond is too deep, some light escapes through the opposite
side of the pavilion.
3. If the cut is too shallow, light can escape from the pavilion before the reflection.