The way a diamond is cut, its width, depth,
roundness, size and position of the facets
determine the brilliance of the stone. Even
if the color and clarity are perfect, if
the diamond is not cut to good proportions,
it will be dull and less impressive to the
Flat, top facet of the diamond.
Crown: Upper portion of
the diamond, above the girdle.
Girdle: Part that separates
the top and bottom of the diamond. This
is the widest part of the stone.
Pavillion: Bottom portion
of the diamond, below the girdle.
Culet: The tip of the bottom
of the diamond. This is the most fragile
piece of the stone.
Diameter: The widest part
of the diamond as measured by the girdle
Depth: Total height of
the diamond measured from the table to the
The table of a diamond has a very important
influence on the overall brilliance of the
stone. The best cut diamonds have a table
that is 56-62% of the size of the girdle
DIAMETER AND THICKNESS
The basis for checking the overall proportions
of a diamond is the diameter of the girdle,
the part that separates the top (crown)
and bottom (pavillion) of the stone. All
other measurements are related as a percentage
of the girdle diameter.
Because very few round
diamonds are absolutely round, the girdle
diameter is measured in at least four directions,
with the highest and lowest values reported
on grading reports. You may see the Measurements
section of a grading report look something
like this: 5.44 - 5.46 x 5.75 mm. This means
that the girdle is 5.46 mm at its widest
point, and 5.44 mm at its least widest point.
The third number represents the Depth of
the diamond, which is the measurement from
the top of the table to the culet.
The pavilion is the bottom portion of the
diamond, below the girdle. The height of
the pavilion greatly contributes to the
diamond's overall brilliance. If the pavillion
is too long or too shallow in proportion
to the rest of the diamond, light will "leak"
out from the bottom of the stone resulting
in a duller looking diamond.
DIAMOND CUT GRADE IS DETERMINED
The overall cut grade of a diamond is determined
by taking into account all of the factors
described above and plotting the results
into a table. The table below shows the
values used in determining the overall cut
grade of a diamond. After each factor of
the cut receives a grade, the overall cut
of the diamond is determined by the lowest
grade any of the factors received. For example,
even if all measurements are ideal but the
table size is only good, the overall cut
grade of that diamond will only be good.
||Thin - Slightly
- Slightly Thick
- Very Thick