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 Cut
Quality For Loose Diamonds
The cut of a
diamond is related to the proportions and symmetry of a diamond.
Often cutters choose to sacrifice some of the
diamond's beauty to achieve a stone that is a larger carat weight.
Cut, more than any other quality aspect, gives the diamond its
sparkle. A diamond gets its brilliance and scintillation
by cutting and polishing the diamond facets to allow the maximum
amount of light that enters through its top to be reflected and
dispersed back, also through its top. With proper cutting
(diagram 1) the light passes through the top, bounces off the
sides, and then travels back out the top, giving the diamond optimum
brilliance. If the diamond is cut too shallow (diagram 2), light
passes through the bottom of the diamond. If the diamond
is cut too deep (diagram 3), light passes through the side of
the diamond, in both cases inhibiting maximum brilliance.
Two popular overall proportion indicators are Total
Depth Percentage (D%) and Table Percentage (T%) . D%
is the diamond's depth expressed as a percentage of its width
(average diameter for rounds). T% is the diamond's "table"
width expressed as a percentage of its overall width (diameters
for rounds). Round diamonds with cutting proportions within
the range generally considered attractive have depths from 55
to 63 percent. The table size of most round diamonds lies
between 56 and 64 percent . With non-round shapes ("fancy"
shapes), much greater proportion variations
are encountered. In most fancy shapes, higher D% and T%
are more common and are dependent on width to length rations.
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QUICK
REFERENCE GUIDE TO DESIRABLE CUT PARAMETERS
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PARAMETERS
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S
H A P E S |
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(In
Importance Order)
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ROUND
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PEAR
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MARQUISE
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OVAL
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Depth%
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59
- 62.5
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59
- 66
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59
- 66
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59
- 66
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Table
%
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53
- 61
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54
- 62
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54
- 62
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54
- 62
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Length/Width
Ratio*
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N/A
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1.50-1.75
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1.75-2.25
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1.30-1.65
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Girdle
Thickness
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V.Thin-Thick
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Thin-Thick
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Thin-Thick
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V.Thin-Thick
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Florescence**
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None
- Faint
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None
- Faint
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None
- Faint
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None
- Faint
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Symmetry
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Polish
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Culet
Size
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None-Med.
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None-Med.
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None-Med.
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None-Med.
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PARAMETERS
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S
H A P E S |
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(In
Importance Order)
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EMERALD
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PRINCESS
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RADIANT
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HEART
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Depth%
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60
- 75
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64
- 79
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62
- 75
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56
- 62
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Table
%
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59
- 75
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60
- 75
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58
- 75
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54
- 62
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Length/Width
Ratio*
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1.4-1.7
/ 1
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1.0-1.2
/ 1
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1.2-1.5
/ 1
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.9-1.1
/ 1
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Girdle
Thickness
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V.Thin-Thick
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Thin-Thick
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V.Thin-Thick
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Thin-Thick
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Florescence**
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None
- Faint
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None
- Faint
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None
- Faint
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None
- Faint
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Symmetry
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Polish
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Excl.-
Good
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Culet
Size
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None-Med.
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None-Med.
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None-Med.
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None-Med.
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*
Only in reference to Fancy Shapes and depends on personal taste.
** Most Significant
with high colors (actually helps lower color diamonds).
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