Diamonds-Capetown Diamond Corporation

The way a diamond is cut and polished is vital.
It is the precision and delicacy of the cut that
dictates the maximum amount of light the
diamond will refract and reflect. The better it
has been cut, the greater will be its
brilliance, sparkle, and fire.
When a diamond is cut to good proportions,
light is internally reflected from one facet to
another and then dispersed through the
crown, or top, of the diamond.(1)

If the cut is too deep, some light will escape through the opposite side of the pavillion, or bottom, of the diamond.(2)
If the cut is too shallow, some light will escape through the pavilion, or bottom, before it can be reflected. (3)
So a well cut diamond is comprised of facets with the correct angles, which are perfectly placed to maximize the diamond's brilliance. It is the quality of the cut and its final polish that unlocks the hidden beauty.

While most diamonds are cut to close tolerances primarily determined by the skill and eye of each cutter, certain measurable standards have evolved to determine whether a diamond is poorly cut or well cut. For better cut diamonds only consider stones that meet the criteria for grades A+/A/B.

NOTE: Poorly cut stones are worth 20-50% less than their well cut counterparts. In other words, a 1 carat round I-VS2 poorly cut diamond could be worth 20-50% less than a 1 carat I-VS2 well cut diamond.

USE THE FOLLOWING CHART WHEN COMPARING THE QUALITY OF CUT
AMONGST CERTIFIED GEMSTONES YOU'RE CONSIDERING.

At this time the GIA does not rate "cut" in lay terms. This chart will help you
decipher the six characteristics that together make up a stones proportions.
Scroll down to view a sample excerpt from a GIA report.
Industry standard cut grades for round stones.

A+ Excellent Ideal cut stones.

Grade A stones with Excellent Polish and Excellent Symmetry.

A Very Good Depth% Table% Girdle

58.8-61.5 55-63 No very thick or extreme

Cutlet Polish Symmetry

No large or chipped Good Good

B Good Depth% Table% Girdle

57.5-62.9 55-65 No extreme thick or thin

Cutlet Polish Symmetry

No large or chipped Good Good

C Fair Depth% Table% Polish Symmetry

<57.5 or >62.9 <55 or >65 Fair Fair

D Poor Depth% Table% Polish Symmetry

<56 or >65 <52 or >69 Poor Poor

Sample excerpt from GIA Certificate with proportional data highlighted

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Industry standard cut grades for round stones.
A+	Excellent	Ideal cut stones.
		Grade A stones with Excellent Polish and Excellent Symmetry.

A	Very Good	Depth%	Table%	Girdle
		58.8-61.5	55-63	No very thick or extreme
		Cutlet		Polish	Symmetry
		No large or chipped		Good	Good

B	Good	Depth%	Table%	Girdle
		57.5-62.9	55-65	No extreme thick or thin
		Cutlet		Polish	Symmetry
		No large or chipped		Good	Good

C	Fair	Depth%	Table%	Polish	Symmetry
		<57.5 or >62.9	<55 or >65	Fair	Fair

D	Poor	Depth%	Table%	Polish	Symmetry
		<56 or >65	<52 or >69	Poor	Poor