A diamond cutter spends years mastering his craft, learning how
best to cut a rough diamond to achieve the ultimate cut with the
fewest imperfections and the least loss of carat weight. The
better the cut, the more valuable the diamond.
Mathematician Marcel Tolkowsky was the first to discover the
exact angles to which a diamond must be cut in order to produce
maximum brilliance. In an Ideal Cut, all of the light that
enters the stone refracts internally from 57 to 58 precisely
placed facets and disperses through the top of the diamond,
producing fire and brilliance. Only a round brilliant cut
diamond can achieve the proven mathematical proportions and
symmetry of an Ideal Cut. However there is some question as to
exactly what an "Ideal cut" in the industry.
Very Good Cut
A Very Good Diamond Cut is close to an Ideal Cut, with only
slight variations in its measurements. It may achieve Ideal Cut
proportions but vary in its polish or symmetry rating. Hence, a
Very Good Cut diamond still creates remarkable brilliance and
luster, often reflecting back the maximum amount of light if its
table and depth percentages match those of an Ideal Cut.
A Good Diamond Cut is well proportioned and reflects back a very good
amount of light.
Many diamonds are “spread” in their cut to increase carat weight
when cutting from the original rough. Although you may end up
with a diamond that appears larger, your sacrifice will be
brilliance and fire.
When cut too deep, a diamond loses light out of the bottom,
leaving the center of the diamond dark in appearance.
When cut too shallow, a diamond loses light out of the bottom,
reducing brilliance and giving the stone a dark, glassy
A diamond's cut is graded by several measurements. Its depth
percentage, a measurement of the height vs. the width of the
stone and its table percentage, a measurement of the diameter of
the top facet of the stone vs. the stone's average width, are
two key factors in determining the quality of a diamond’s cut.
These percentages are detailed on the GIA Gem Trade Laboratory
Diamond Grading Report or other grading laboratories that
accompanies most of our store's loose diamond.