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IGI REPORT, PLEASE, HELP

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martin_a

Rough_Rock
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May 3, 2008
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hello;

Please, explain me the following.
Report from IGI:
carat 1.06
color h
clarity vs2
cut excellent
polish very g.
symm. very good

measur. 6.48-6.5x4.1
table 58%
crown height -angle 15% - 35.5
pavil. depth -angle 44.5% -41.6
girdle thin to med
culet pointed
total depth 63%

fluor. slight





When I input the # in HCA i got 5.3

My question is : what is cut grade then? why is excellent and in the same report the measurements show that it should be fair - good.
 

Stephan

Ideal_Rock
Joined
Feb 13, 2003
Messages
2,917
You can find a better diamond than this one.
Do you live in Europe?
GIA, AGS or HRD have a better reputation than EGL or IGI.
And even then, keep using HCA to eliminate the bad candidates.
Good luck!
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Welcome Martin!

Queen Mum is right ( Love the new av Stephan, I feel as if I should be curtsying in your presence
9.gif
) You can do better than this diamond, have you already bought it? With the crown and pavilion angles, it is what we call a steep deep. This means very basically these angles are too steep for the best light return( sparkle) and the diamond may leak light and look dark. Labels such as Excellent for cut don't mean a thing unfortunately, these terms are often used loosely and do not guarantee you a well cut stone. IGI are considered by some to be less accurate on grading in some cases as QM said, here is a link where you can read more.

http://diamonds.pricescope.com/grading.asp

Here is a range of numbers you can use to look for alternatives

depth 60 - 62.4%
table- 54-57 or even 58 if the cut is good
crown angle - 34- 35
pavilion angle - 40.6- 41
With the crown and pavilion angles evaluate diamonds with shallower combos ( CA 34- PA 40.6) and steeper ( CA 35 - PA 41) to make sure they work in harmony for that particular diamond, an Idealscope and vendor input/ your own eyes are needed for this.

polish and symmetry - very good and above
girdle- thin to slightly thick, medium, avoid extremes such as thin to very thick etc.

To make finding a lovely diamond easier if you decide against this one, centre your search around AGS0 and GIA Excellent cut grade.
 

Stephan

Ideal_Rock
Joined
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Messages
2,917
Hi Lorelei!
Pricescope should pay you for all the help you provide to newbies.
Martin, here is an interesting link where a famous cutter is talking about to deep pavilions.
Lorelei, you don''t have to

curtseyX.gif
 

Lorelei

Super_Ideal_Rock
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Messages
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Date: 5/4/2008 5:01:15 AM
Author: QueenMum
Hi Lorelei!
Pricescope should pay you for all the help you provide to newbies.
Martin, here is an interesting link where a famous cutter is talking about to deep pavilions.
Lorelei, you don''t have to
OMG, that is too funny!!!
31.gif


And you are too kind, thank you, I enjoy helping!
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
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Messages
18,423
Date: 5/3/2008 10:26:58 PM
Author:martin_a
hello;

Please, explain me the following.
Report from IGI:
carat 1.06
color h
clarity vs2
cut excellent
polish very g.
symm. very good

measur. 6.48-6.5x4.1
table 58%
crown height -angle 15% - 35.5
pavil. depth -angle 44.5% -41.6
girdle thin to med
culet pointed
total depth 63%

fluor. slight





When I input the # in HCA i got 5.3

My question is : what is cut grade then? why is excellent and in the same report the measurements show that it should be fair - good.
In many cass IGI follows and even uses GIA''s grading. Those proportions are very close to gIA Excellent i think - but GIA Excellent has a cut off at 62.9% depth.

If you really want to go deeply into the debate between various scientists and labs then read this http://journal.pricescope.com/Articles/50/1/Letter-to-the-Editor-of-the-Australian-Gemmologist.aspx
 

martin_a

Rough_Rock
Joined
May 3, 2008
Messages
4
Thank you.

I guess the way I worded my question was a bit vague.
What I actually wanted to find out was:
1. For this IGI report cut is the outcome of the measurements (correct me if I am wrong)
2. With the same measurements I get hca 5.3 which is just between fair and good.
What I actually wanted to find out was:
For IGI it is excellent for GIA as Harry mentioned it was close excellent, somehow for HCA is not even good. Are we talking about much stricter standards or HCA has different set of standards (what good in hca world is bad in GIA and vice versa) ?
Also if someone would not mind could I get an idea what would the good price on that one be and what would be the difference in price if pavil. goes from 41.6 to 40.6.
 

martin_a

Rough_Rock
Joined
May 3, 2008
Messages
4
Date: 5/4/2008 4:19:30 AM
Author: Lorelei


http://diamonds.pricescope.com/grading.asp


Here is a range of numbers you can use to look for alternatives


depth 60 - 62.4%

table- 54-57 or even 58 if the cut is good

crown angle - 34- 35

pavilion angle - 40.6- 41

With the crown and pavilion angles evaluate diamonds with shallower combos ( CA 34- PA 40.6) and steeper ( CA 35 - PA 41) to make sure they work in harmony for that particular diamond, an Idealscope and vendor input/ your own eyes are needed for this.
Hello LORELEI;
Are you saying that "cut" is not a sum of depth, table , crown , pavil?
 

diamondseeker2006

Super_Ideal_Rock
Premium
Joined
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Messages
58,547
The crown and pavilion angles must be complementary, and the table and depth must be within a certain range to be considered "ideal" or "excellent". When the depth is greater than the 60-62 range, it can negatively affect the diameter of the stone thereby causing it to appear smaller than it would with less depth. I always look for depths of 60-62, personally.
 

Lorelei

Super_Ideal_Rock
Premium
Joined
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Messages
42,064
Date: 5/4/2008 1:21:58 PM
Author: martin_a







Date: 5/4/2008 4:19:30 AM
Author: Lorelei


http://diamonds.pricescope.com/grading.asp


Here is a range of numbers you can use to look for alternatives


depth 60 - 62.4%

table- 54-57 or even 58 if the cut is good

crown angle - 34- 35

pavilion angle - 40.6- 41

With the crown and pavilion angles evaluate diamonds with shallower combos ( CA 34- PA 40.6) and steeper ( CA 35 - PA 41) to make sure they work in harmony for that particular diamond, an Idealscope and vendor input/ your own eyes are needed for this.
Hello LORELEI;
Are you saying that 'cut' is not a sum of depth, table , crown , pavil?
Hi Martin!

Sorry, what I meant to say was that some of us PSers generally prefer a slightly smaller table at 54- 57%, that you could certainly consider a 58% table if the rest of the diamond had good proportions, in other words, if the overall cut and performance was great.

Also by limiting to 62% depth only means that some excellent stones could possibly be missed, that is why I personally recommend 62.4% as my personal cutoff. Going slightly past 62% won't always have a negative effect on the diamond by making it look much smaller necessarily.
1.gif
I did forget to add in my earlier post, and I normally do this but forgot this time for some reason, that the 62.4% is my preferred cutoff for depth.
 

martin_a

Rough_Rock
Joined
May 3, 2008
Messages
4
Thank you.
I am reposting the questions below that I believed were just missed ( because I asked too many questions:))
I guess the way I worded my question was a bit vague.
What I actually wanted to find out was:
1. For this IGI report cut is the outcome of the measurements (correct me if I am wrong)
2. With the same measurements I get hca 5.3 which is just between fair and good.
What I actually wanted to find out was:
For IGI it is excellent for GIA as Garry H mentioned it was close excellent, somehow for HCA is not even good. Are we talking about much stricter standards or HCA has different set of standards (what good in hca world is bad in GIA and vice versa) ?
Also if someone would not mind could I get an idea what would the good price on that one be and what would be the difference in price if pavil. goes from 41.6 to 40.6.
 

JulieN

Super_Ideal_Rock
Premium
Joined
Jul 25, 2005
Messages
13,375
Date: 5/5/2008 2:04:54 PM
Author: martin_a

Thank you.
I am reposting the questions below that I believed were just missed ( because I asked too many questions:))

I guess the way I worded my question was a bit vague.
What I actually wanted to find out was:
1. For this IGI report cut is the outcome of the measurements (correct me if I am wrong)
2. With the same measurements I get hca 5.3 which is just between fair and good.
What I actually wanted to find out was:
For IGI it is excellent for GIA as Garry H mentioned it was close excellent, somehow for HCA is not even good. Are we talking about much stricter standards or HCA has different set of standards (what good in hca world is bad in GIA and vice versa) ?
Also if someone would not mind could I get an idea what would the good price on that one be and what would be the difference in price if pavil. goes from 41.6 to 40.6.

probably it is like GIA''s. everything must be in a certain range.

however, this range does not take into account the idea of complementary angles based on the table, which is what HCA does.
 

Stephan

Ideal_Rock
Joined
Feb 13, 2003
Messages
2,917
When GIA gives an excellent cut grade, are they talking about yield?
31.gif

Sorry, I didn''t want to hijack your thread!
 

zerj

Rough_Rock
Joined
Apr 25, 2008
Messages
78
I don''t know what exactly determines the ''cut'' grade at the testing labs. Certainly those measurements have a strong effect on the cut grade but I believe other factors may be involved as well. Correct me if I am wrong but I thought AGS graded diamonds wouldn''t use thier top grade AGS0 if polish/symetry weren''t also listed as excellent. So at that lab at least there are 2 other factors.

As far as the HCA goes I don''t believe any of the labs officially use the HCA for grading. One important thing to note on the HCA is the different grading outlines of ''excellent'' for GIA and AGS labs are shown. If you look at the graph spat out by HCA it''s pretty clear that some GIA excellents are coming from the blue (5-7) area''s in the HCA.

I don''t know why GIA would grade these ''excellent'' cuts unless either they completely don''t believe the HCA or there are mitigating factors i.e. excellent symmetry overcoming the suspect rough cut dimensions. I thought I saw a post on here mentioning that there were some very pretty stones that had an HCA above 2.0 however the the overall percentage of these are a lot lower than the percentage of nice stones with an HCA below 2.0. So it just isn''t worth it as a consumer to examine them especially if for the most part we are buying over the internet sight unseen.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
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Messages
18,423
Date: 5/5/2008 3:29:47 PM
Author: zerj
I don''t know what exactly determines the ''cut'' grade at the testing labs. Certainly those measurements have a strong effect on the cut grade but I believe other factors may be involved as well. Correct me if I am wrong but I thought AGS graded diamonds wouldn''t use thier top grade AGS0 if polish/symetry weren''t also listed as excellent. So at that lab at least there are 2 other factors.

As far as the HCA goes I don''t believe any of the labs officially use the HCA for grading. One important thing to note on the HCA is the different grading outlines of ''excellent'' for GIA and AGS labs are shown. If you look at the graph spat out by HCA it''s pretty clear that some GIA excellents are coming from the blue (5-7) area''s in the HCA.

I don''t know why GIA would grade these ''excellent'' cuts unless either they completely don''t believe the HCA or there are mitigating factors i.e. excellent symmetry overcoming the suspect rough cut dimensions. I thought I saw a post on here mentioning that there were some very pretty stones that had an HCA above 2.0 however the the overall percentage of these are a lot lower than the percentage of nice stones with an HCA below 2.0. So it just isn''t worth it as a consumer to examine them especially if for the most part we are buying over the internet sight unseen.
Good explanation Zerj

Also no one sends me diamonds to grade for money, so I can afford to be hard
10.gif
 
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