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Jul
15

Diamond Proportions

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All diamonds are cut differently, some better than others. Depending on how they are cut will depend on how nice the diamond is. For example, if the proportions are skewed or incorrect one side might be longer than the other and your diamond could be lopsided. In addition, the sparkle that you can get out of the diamond depends greatly on the proportions because of light refraction. Below you will find some of the proportions to look for with each basic shape that will help you get the most out of your diamond.

Depth Percentage – The depth of a stone measured from the table to the culet. It is expressed as a percentage of the stone’s diameter at the girdle.

Table Size – The size of the table of a fashioned diamond is expressed as a percentage of the stone’s narrow-girdle diameter. On a round brilliant, it is measured from corner to opposite corner, rather than from flat side to flat side.

Ratio : Is referred to the overall diamond in LENGTH to WIDTH.

Girdle – The outer edge, or periphery, of a fashioned stone; the portion that is usually grasped by the setting or mounting; the dividing line between the crown and pavilion.

ROUND BRILLIANT
Excellent Very Good Good Fair / Poor
Depth % 59.0% – 61.0% 58.5% – 58.9% or 61.1% – 62.5% 58.0% – 58.4% or 62.6% – 63.0% Outside the ranges
Table % 52.4% – 57.5 % 57.6% – 59.5% 59.6% – 62.5% Outside the ranges
Ratio 1.00 : 1.00 1.001 – 1.005 : 1.00 1.006 – 1.01 : 1.00 Outside the ranges
Girdle Medium, Facted Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

MARQUISE BRILLIANT
Excellent Very Good Good Fair / Poor
Depth % 56.0% – 72.0% 52.0% – 55.9% or 72.1% – 75.0% 48.0% – 51.9% or 75.1% – 78.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 61.0% 61.1% – 62.5% Outside the ranges
Ratio 1.95 – 2.05 : 1.00 1.80 – 1.94 or 2.06 - 2.10 : 1.00 1.70 – 1.79 or 2.11 - 2.15 :1.00 Outside the ranges
Girdle Medium, Facted Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

OVAL BRILLIANT
Excellent Very Good Good Fair / Poor
Depth % 56.0% – 65.0% 55.0% – 55.9% or 65.1% – 67.5% 54.0% – 54.9% or 67.6% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 61.0% 61.1% – 62.5% Outside the ranges
Ratio 1.45 – 1.55 : 1.00 1.35 – 1.44 or 1.56 - 1.60 : 1.00 1.30 – 1.34 or 1.61 - 1.65 : 1.00 Outside the ranges
Girdle Medium, Facted Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

PEAR SHAPE
Excellent Very Good Good Fair / Poor
Depth % 56.0% – 65.0% 55.0% – 55.9% or 65.1% – 67.5% 54.0% – 54.9% or 67.6% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 61.0% 61.1% – 62.5% Outside the ranges
Ratio 1.55 – 1.65 : 1.00 1.45 – 1.54 or 1.66 - 1.70 :1.00 1.35 – 1.44 or 1.71 - 1.75 : 1.00 Outside the ranges
Girdle Medium, Facted Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

HEART SHAPE
Excellent Very Good Good Fair / Poor
Depth % 56.0% – 65.0% 55.0% – 55.9% or 65.1% – 67.5% 54.0% – 54.9% or 67.6% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 61.0% 61.1% – 62.5% Outside the ranges
Ratio 1.00 – 1.05 : 1.00 1.06 – 1.10 : 1.00 1.11 – 1.20 : 1.00 Outside the ranges
Girdle Medium, Facted Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges


RADIANT CUT
Excellent Very Good Good Fair / Poor
Depth % 60.0% – 63.0% 59.0% – 59.9% or 63.1% – 65.0% 58.0% – 58.9% or 65.1% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 65.0% 65.1% – 75.0% Outside the ranges
Ratio 1.00 – 1.20:1.00 1.21 – 1.25 :1.00 1.26 – 1.35 : 1.00 Outside the ranges
Girdle Medium Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

EMERALD CUT
Excellent Very Good Good Fair / Poor
Depth % 60.0% – 63.0% 59.0% – 59.9% or 63.1% – 65.0% 58.0% – 58.9% or 65.1% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 65.0% 65.1% – 75.0% Outside the ranges
Ratio 1.35 – 1.55 : 1.00 1.30 – 1.54 or 1.56 - 1.65 : 1.00 1.25 – 1.29 or 1.66 - 1.70 : 1.00 Outside the ranges
Girdle Medium Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

ASSCHER CUT
Excellent Very Good Good Fair / Poor
Depth % 59.0% – 65.0% 58.0% – 58.9% or 65.1% – 67.0% 57.0% – 57.9% or 67.1% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 65.0% 65.1% – 70.0% Outside the ranges
Ratio 1.00 – 1.05 : 1.00 1.06 – 1.09 : 1.00 1.10 – 1.12 : 1.00 Outside the ranges
Girdle Medium Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

PRINCESS CUT
Excellent Very Good Good Fair / Poor
Depth % 60.0% – 75.0% 59.0% – 59.9% or 75.1% – 77.0% 58.0% – 58.9% or 77.1% – 79.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 65.0% 65.1% – 75.0% Outside the ranges
Ratio 1.00 – 1.05 : 1.00 1.06 – 1.10 : 1.00 1.11 – 1.15 : 1.00 Outside the ranges
Girdle Medium Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

CUSHION SHAPE
Excellent Very Good Good Fair / Poor
Depth % 59.0% – 65.0% 58.0% – 58.9% or 65.1% – 67.0% 57.0% – 57.9% or 67.1% – 70.0% Outside the ranges
Table % 53.0% – 57.9 % 58.0% – 65.0% 65.1% – 75.0% Outside the ranges
Ratio 1.00 – 1.20 : 1.00 1.21 – 1.25 : 1.00 1.26 – 1.35 : 1.00 Outside the ranges
Girdle Medium Thin to Thick, Facted Very Thin to Very Thick, Facted Outside the ranges

 

Visual Representation