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Advice on a Diamond (Newbie)

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mmja07

Rough_Rock
Joined
Apr 10, 2009
Messages
17
Hi! Just starting my search for a diamond. Been trying to read up on everything "I should know", and getting overwhelmed.

What would be the particular critique on the following diamond: (attached is the IS)

CCCC: Round, GVS1, 1.54
Measurements: 7.38 x 7.43 x 4.60

Depth: 62.1
Table: 56
Crown Angle: 35
Crown: 15.5%
Pavilion Angle: 40.8
Pavilion: 43%
Lower Girdle: 75
Girdle: Thin to Medium Faceted

Pol: Excellent
Sym: Excellent
Flu: None

Are there any recommedations for measurements or the other numbers for this size range??

Appreciate all the help! :)

dia1_154_xx.jpg
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 4/10/2009 8:43:44 AM
Author:mmja07
Hi! Just starting my search for a diamond. Been trying to read up on everything 'I should know', and getting overwhelmed.

What would be the particular critique on the following diamond: (attached is the IS)

CCCC: Round, GVS1, 1.54
Measurements: 7.38 x 7.43 x 4.60

Depth: 62.1
Table: 56
Crown Angle: 35
Crown: 15.5%
Pavilion Angle: 40.8
Pavilion: 43%
Lower Girdle: 75
Girdle: Thin to Medium Faceted

Pol: Excellent
Sym: Excellent
Flu: None

Are there any recommedations for measurements or the other numbers for this size range??

Appreciate all the help! :)

Hi mmj,

The Idealscope image shows some leakage as you can see, probably due to the 35/ 40.8 crown and pavilion combo. This is a duo which can in some cases be fine or can show leakage as above, hence my preference for an Idealscope image in these cases. The numbers for well cut rounds stay the same regardless of size, so you are on the right track. Here are some numbers you can use as a guide to help you find a well cut round diamond.

depth - 60 - 62% - although my personal preference is to allow up to 62.4%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above

note - with crown and pavilion angles at the shallower ends ( CA 34- PA 40.6) and steeper ( CA 35- PA 41) check to make sure these angles complement in that particular diamond - eyeballs, Idealscope, trusted vendor input - check as appropriate!


As the above implies, configurations depend on each other. A little give here can still work with a little take there.


From expert John Pollard.


With that said, here's a "Cliff's Notes" for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded): A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle. If pavilion angle = 40.6 lean toward a 34.5-35.0 crown. If pavilion angle = 41 lean toward a 34.0-34.5 crown.



GIA "EX" in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).
 
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