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Learn about Table Percentage
The table is the large flat facet on the crown or top of a diamond.
The table directly affects scintillation, or sparkle in a diamond.
The combination of table size and crown angle governs the balance between brilliance,
flashes of white light returning to the eye from within the diamond, and dispersion,
the play of spectral colors seen by the eye created by refracted light as it prisms
through a diamond's facets.
Research indicates that it is better to select a round brilliant cut diamond that has a
table percentage between 53 and 62%. Diamonds with table percentages between this range deliver
greater brilliance and are considered to have very fine-ideal cut.
The following offers you information to support this position.
Tolkowsky Cut
The Tolkowsky theoretically brilliant cut is a standard of proportions and facet angles
that were mathematically calculated by Marcel Tolkowsky in 1919. The Tolkowsky theoretical
model presents 53% as ideal table percentage. Today, highly respected gemological institutions
endorse standards that include variations from the Tolkowsky model.
Two highly respected gemological institutions have published systems for grading diamond cut:
the Gemological Institute of America (GIA), and the American Gem Society (AGS).
These highly respected gemological institutions have developed
systems for classifying cut quality.
GIA's system as outlined in GIA's diploma study course
uses this four class system:
Class 1 = Ideal, Class 2 = Fine, Class 3 = Fair, Class 4 = Poor.
GIA Class 1 Ideal endorses a table percentages between 53 and 60% as Ideal and 61% to
64% as GIA Class 2 Fine
The AGS system uses a 0 to 10 system: Cut grade 0 as Ideal, 2 as Very Fine and 10 being the
lowest grade and quality.
The AGS cut grade 0 ideal endorses table percentages between 51.6% to 57.5%
as ideal with 57.6 to 62% as very fine AGS cut grade 2.
There are slightly more very fine cut diamonds available with table sizes that
are slightly over 60%. To say that diamonds with table percentages under 60% are only acceptable is like
saying D - flawless is the only acceptable choice in regards to a diamonds color and
clarity grades. As a Certified-Gemologist Appraiser, I have examined many very fine cut diamonds with
table percentages which vary slightly from perfect ideal. These diamonds also display extreme
brilliance.
Unlike strict ideal cut, selecting a diamond that has very fine cut offers
the option of greater savings and more diamond choices. Today only a few diamond cutters
cut diamonds with rare table percentages under 58%. In contrast, there are slightly more
diamonds available cut with table percentages between 59% and 62%. Diamonds in this range
also display extraordinary brillliance. AGS cut grade 2 (very fine) includes diamonds
with table percentages up to 62%. The great majority of diamonds sold today have table
percentages much higher than 62%. To select a diamond that has a table percentage
under 62% ensures you have chosen a diamond that is very fine in cut quality with regards to
table percentage.
Recently, the Gemological Institute of America announced a 59% table produces greater
brilliance. GIA's conclusion was based on evidence provided by a new three-dimensional
computer ray tracing instrument. Fine cut diamonds that have table sizes below
62% cost more because a larger portion of the rough diamond is sacrificed to cut
ideal proportions.
Bill Boyajian, President of the Gemological Institute of America
shares information regarding ideal table size.
Research indicates that table sizes that are under 62% deliver
exceptional brilliance. Diamonds with table sizes under 59% create slightly
greater dispersion of light which results in the emission of slightly more spectral colors.
Diamonds with table sizes that are 59%, or slightly higher, offer
the viewer greater amount of brilliance, or white light returning to the eye.
When table size is lower, dispersion increases and brilliance is lowered. When table
size is higher, brilliance increases and dispersion is lowered. Because beauty is determined
by the eye of the beholder, it is unlikely that a specific table percentage will be
absolutely defined by GIA. Research indicates, and gemologists agree that diamonds
with table measurements under 62% have superior brilliance and dispersion.
Diamonds in these ranges usually require that the diamond cutter cut away more
diamond weight in order to achieve this higher quality of brilliance.
The brilliance of your diamond depends on proper cutting. Certified-Plus Diamonds selects only
ideal to premium cut diamonds to ensure that the diamond you choose will be as brilliant as
it is beautiful. A diamond with these premium proportions will cost more but its brilliance
is well worth the added investment.
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