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How many facets?
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The standard number of facets of a Round Brilliant Cut gemstone is 57,
or 58 if the culet is included. On the Crown or upper part of the Diamond,
these consist of 1 table facet, 8 bezel facets, 8 star facets, and 16 upper
girdle facets for a total of 33. On the pavilion, or bottom part of the
Diamond, there are 16 lower girdle facets, 8 pavilion main facets and 1 culet.
What are the origins of the Round Brilliant Cut?
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Round is from the Middle English word “Rounden”, which means “Secret”.
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Although no single inventor has officially been credited with the invention of
the Round Brilliant Cut, many sources do credit a Venetian cutter named
Vincenzio Perruzzi and date the Brilliant's introduction to the 18th Century.
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The Russian mathematical genius Marcel Tolkowsky, a member of a large and
powerful Diamond family, subsequently calculated the cuts necessary to create
the ideal Diamond shape. As part of his PhD thesis in mathematics, Tolkowsky
considered variables such as the index of refraction and covalent bond angles
to describe what has become known as the Round Brilliant Cut.
What works best for Round Cuts?
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This cut is optically the most efficient. The Round Brilliant boasts one of the
best recoveries for well shaped rough Diamond; this translates into good value
for consumers.
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The Round Brilliant Cut is designed to provide maximum optics for the
brilliance and scintillation, making the gem sparkle and dance in the light.
Due to it's huge popularity there is a premium for purchasing "Ideal Cuts", and
they are more rare in the market. Cutting to "Ideal" generally entails losing
more weight from the rough Diamond than regular proportions. It is usually
possible to retain more weight from a Rough (unpolished) Diamond if it is cut
into a Fancy shape than if it is cut to a Round. The Depth percent of round
diamonds should range between 58.3% and 63%, table percent should be between
53% and 67%. Perfectionists look for a Depth of 59.5% to 62% with a table
of 55% to 58%.
The Quality Diamonds Basic Grading Chart has been used to
determine the quality of individual stones we sell on this website, using Table
and Depth percentages to give a general guide to a stones quality. We have used
this simplified method to assist customers who prefer not to delve into very
specific details, after all, if you are not completely satisfied with your
purchase, you have the right to a full refund, or to exchange your diamond for
30 days.
Quality Diamonds Basic Grading Chart
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Table %
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53.0%-58.0%
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52.0%-60.0%
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51.5%-63.0%
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51.0%-64.0%
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50.5%-67.0%
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50.0%-70.0%
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49.0%-72.0%
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<49.0%
>72.0%
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Total Depth %
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58.00%-62.30%
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58.30%-62.99%
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<58.30%
>62.99%
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The Full Grading Chart is the recognised chart for
grading diamonds right down to the finest detail. This chart is intended for
the true perfectionist and as such, you may want to call us on 0800 612 1017 to
talk to a diamond expert to ensure you are getting exactly what you require.
Full Grading Chart
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Table %
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53.0%-58.0%
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52.0%-60.0%
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51.5%-63.0%
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51.0%-64.0%
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50.5%-67.0%
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50.0%-70.0%
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49.0%-72.0%
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<49.0%
>72.0%
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Crown Angle
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34.0°-34.7°
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33.0°-35.1°
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32.1°-35.8°
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31.6°-36.4°
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30.1°-37.9°
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29.6°-39.4°
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29.0°-40.5°
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<29.0°
>40.5°
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Crown Height %
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14.3%-16.3%
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13.5%-16.8%
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11.6%-17.9%
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11.1%-18.1%
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9.6%-19.3%
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8.5%-20.5%
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7.8%-21.8%
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<7.8%
>21.8%
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Pavilion Depth %
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42.8%-43.2%
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42.5%-43.5%
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42.0%-44.0%
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41.5%-44.9%
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41.0%-45.5%
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40.5%-46.0%
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38.0%-48.0%
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<38.0%
>48.0%
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Girdle Thickness
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Thin to Medium
Or
Medium to Slightly thick
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Very thin to Medium
Or
Thin to Slightly thick
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Very thin to Slightly thick
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Very thin to Thick
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Very thin to Very thick
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Extremely thin to Extremely thick
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Total Depth %
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58.00%-62.30%
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58.30%-62.99%
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<58.30%
>62.99%
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Polish / Symmetry
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Excellent-Very Good
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Good to Excellent
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Fair to Good
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Poor
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