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AGA Diamond

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niko555

Rough_Rock
Joined
Oct 31, 2007
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I have been in search for e-ring and I came accross AGA diamond that has the following specs:
7 X6.9X 4.72
AGA Cut - 2B
Apprx GIA color - H
Apprx GIA cut- VS2
Flouresense -negligible
67.9% depth, 56.8% table , 15.4% crown height
1.52ct

How are these parameters compare to GIA? What would be price diff if it was no flourense with 59 table and 61 depth?
 
I''d expect this diamond to be priced somewhere around $10,000 give or take (found that number using the price stats charts for a 2B diamond which is found under the price menu above). The depth of that stone is very large (ideal cut diamonds are often below 62% in depth), hence the 2B rating. Do you know the crown or pavillion angles? Try plugging those into the cut adviser on the tools menu and see what kind of performance you''d expect from those numbers. Since most of a diamonds visual performance is determined by its cut, if you haven''t done so already, compare that stone side by side with some 1A cuts to see how sensitive you are to cut.
 
If you post the cut angles, girdle characteristics, and the polish and symmetry... I can run them on GIA Facetware (or you can do the same by finding it on google) and you can get an estimate of the GIA cut grade.
 
Also, is this an AGA graded diamond or a diamond that the dealer has run through a table and predicted the AGA grade.
 
35.7% crown angle and 15.4% crown height
 
45% pavilion depth... thanku very much.
 
Is it a round stone or a nearly square one?
 
Is this supposed to be a round stone?
 
????
 
If this is a round brilliant, the total depth of 67.9% is outrageous. It could well be another shape, and then, the following info is useless.

Based upon the available info, and assuming that it is a round, this stone is not a 2B in the AGA-charts. Total depth is 67.9%, crown height is 15.4%, leaving 52.5%% for girdle and pavilion. Assuming a maximum of 5.5% (according to AGA 2B) for the girdle, the pavilion depth is minimum 47.0%. This leads us to an AGA-score of 4A at best.

The diameter of the stone is that of a well-cut 1.25 Ct.

The indication of approximate grades on colour and clarity (not cut as indicated) leads to believe that the stone has no grading report. What does ''apprx'' mean then? Is it actually 1 grade lower on each, or 2, or more? If we can deduct from very limited info, that the approximate AGA cut-grade is 4A in stead of 2B, how reliable is that colour- and cut-grade then?

All in all, I see more questions than answers about this stone.

Live long,
 
Thank you for your replies. The stone does have AGA certificate... and the total parameters as stated on the certificate are as follows:

It is a round 1.52 ct stone:

7 X6.9X 4.72
AGA Cut - 2B
Apprx GIA color - H
Apprx GIA cut- VS2
Flouresense -negligible
67.9% depth, 56.8% table , 45% pavilion depth
35.7% crown angle and 15.4% crown height

... thank u very much.


 
Provided the girdle measures anywhere from thin to slight thick 2B is correct.

All one needs to do is plug in the measures on the Do It Yourself grader to confirm the grade on an AGA report.
There are "rules" which are automated into the grading tool, and many folks don''t apply the rules looking instead only at the charts.
The rules are an essential element of arriving at a proper grade.
 
Thank you. So back to my original question - How are these parameters compare to GIA cert? What would be price diff in pricing if it was no flourense with better paramer for depth...
 
I imagine the value could be 20% to as much as 35% less than an "ideal cut", an AGA "1A to 1B" of the same color and clarity due to the overly deep perception. Much worse stones exist and this one may look very nice to you, but there are better cut stones in circulation which bring higher prices. We try to make our color and clarity grading to properly meet GIA standards.
 
The price should be significantly lower than an ideal cut diamond. In addition, it faces up only 7.00 mm across, so comparing it to normal 1.50 carat diamonds (appx 7.40 mm) is not really apples to apples.

GIA would give it Fair in cut (depth).
AGS cut guides predict 7 in light performance (table/angles).


Date: 11/5/2007 5:53:27 AM
Author: Paul-Antwerp

If this is a round brilliant, the total depth of 67.9% is outrageous. It could well be another shape, and then, the following info is useless.

Based upon the available info, and assuming that it is a round, this stone is not a 2B in the AGA-charts. Total depth is 67.9%, crown height is 15.4%, leaving 52.5%% for girdle and pavilion. Assuming a maximum of 5.5% (according to AGA 2B) for the girdle, the pavilion depth is minimum 47.0%. This leads us to an AGA-score of 4A at best.

The diameter of the stone is that of a well-cut 1.25 Ct.

The indication of approximate grades on colour and clarity (not cut as indicated) leads to believe that the stone has no grading report. What does 'apprx' mean then? Is it actually 1 grade lower on each, or 2, or more? If we can deduct from very limited info, that the approximate AGA cut-grade is 4A in stead of 2B, how reliable is that colour- and cut-grade then?

All in all, I see more questions than answers about this stone.

Live long,
Click to expand...
Perhaps compare it to poorly made 1.25 ct diamonds in terms of pricing.
 
About 8 to 10 years ago, a fellow gemologist appraiser friend of mine published a highly complex price guide based on actual asking prices for many sizes of round and fancy shape diamonds. It used the AGA Cut Class system and he personally measured each of the thousands of diamonds tio determine the cut class before the publication was made quarterly. It was too heavy for becoming profitable because of the high cost of shipping it, and it was just a bit ahead of the digital, intnert age where large files could be emailed for free.

He and I initially figured that the better the cut, the higher the asking price, but what we found was unexpected. Actually, the asking prices of fine cuts often were equal to or less than the no rules world of secondary and thrid level cut diamonds. Why? Because diamonds cut to non-standard proportions are priced according to the whim of each dealer and highly subject to any offer to purchase for most any price where a profit might exist. Finely cut diamonds need to be priced in a much tighter, highly competitive manner, so that people will know they are valued correctly. Little discount is available after the asking price is set.

Had we been able to track actual transaction prices I believe we may have found what we had expected; transaction pricing for fine stones being higher than for poorer cut ones.

Asking prices on less than finely cut diamonds are not always value based, but based on how much you might know or how much might be offered. If this diamond''s value is that of a 1.25ct well cut stone, then we are seeing an 18% value reduction for cut quality based only on weight without regard to how much more 1.50ct diamonds are said to be worth for their extra weight increment. I think this puts my low estimate of 20%+ right near the right zone for discounting.
 
Thank you very much for this information. It sounds this is not the diamond that I like. I compared it to 1.1 ct stone GIA with ideal cut and they look similar in size...

Would would be ideal parameters in terms of depth/height/width for a stone of 1.5 ct?

I was looking at GIA stones but also was told that AGA stones are graded accurately to match GIA certs and I would like to ensure that it matches...
 
Hi niko555, welcome to PS.
35.gif
I would run very fast away from that diamond. Sounds like you already figured that one out.
2.gif
You would end up paying for weight that is hidden in the depth of the stone (not visible in the 'width' or horizontal plane [referred to as spread] of the stone).

A really good resource is to read the sections under the knowledge section at the top of the page. To go directly to the cut charts in that section is
http://diamonds.pricescope.com/round.asp

The spread chart from that faq section...
https://www.pricescope.com/community/threads/mm-to-carat-stone-conversion-chart.17578/

Also Amazon has a really nice size chart for weight too (I just can't get to it right now)

If you would like to post your criteria for a stone selection (such as size, color, clarity, budget), many on here are always happy to give suggestions for stones if you are interested (you can take or leave the suggestions, half the fun is doing the searches!). If not interested in getting suggestions, then refer to the Holloway Cut Advisor here (plug in the #s) - look for a value under two - values over two usually would be weeded out, anything under two could be considered for further eval (does not matter the actual # - a 2 is not better than a 1 for example - although there is a caveat that often people prefer stones with a score between 1 and 2 as opposed to under 1. This is a good tool for any stones you cannot see with your eyes (i.e. internet searching). Aiming for a stone that falls within the white box will get you a stone with a cut that would meet possible criteria for an AGS 0. Some like to aim for a stone that falls within both the white box and the green one and thus is both an AGS0 and GIA Ex candidate.

http://www.pricescope.com/cutadviser.asp



ETA:
I believe this is the size chart from amazon...
images.amazon.com/media/i3d/01/actual-diamond-size.pdf
 
Date: 11/5/2007 12:33:50 PM
Author: oldminer
Provided the girdle measures anywhere from thin to slight thick 2B is correct.

All one needs to do is plug in the measures on the Do It Yourself grader to confirm the grade on an AGA report.
There are ''rules'' which are automated into the grading tool, and many folks don''t apply the rules looking instead only at the charts.
The rules are an essential element of arriving at a proper grade.
Click to expand...
Forgive me, Dave, but I do not understand.

The stone has a pavilion depth of 45%. If I check the charts, this indicates the stone being at least 3A.

Calculating a total depth of 67.9, with a crown height of 15.4 and a pavilion depth of 45, I see a girdle thickness of 7.5%. In no way can this be considered thin to slightly thick. I would think that this is extremely thick, which would bring the stone back into a grade of 4A.

I look forward to your clarification.

Take care,
 
Paul; You are not alone. Few people have read the "rules". The flex built into them allows for what I consider the logic of pricing to mix properly with correct grading.

This is on the website along with the cut grader, but most folks rush through the charts.

AGA Rules For Determining "Overall" Cut Grade
Chart: Please Select... Emerald Heart Marquis Pear Princess Oval Radiant Round Old Euro Cut
1A grade:
All characteristics are best when 1A, but may include a single 1B characteristic. You pay a premium for this cut and you should insist on getting exactly what you are paying for.

1B grade:
All characteristics need to be all 1B or 1A to 2B. Only a single class 2 characteristic is permitted. The class 2 characteristic should be within 2% or 2 degrees of the 1B characteristic.

2A grade:
All characteristics need to be 2A or 1A thru 2B. Only a single 2B parameter is permitted and it must be within 2% or 2 degrees of the 2A characteristic. (crown angle degree rounds only)

2B grade:
All characteristics need to be all 2B or 1A thru 3A. Only a single 3A characteristic is permitted and the 3A characteristic cannot be a very thick girdle or more than 1 degree too shallow a crown angle. The 3A characteristic must be within 2% or 1 degree of the 2B characteristic. (crown angle degree rounds only)

3A grade:
A stone may be all 3A or 1A thru 4A. Any characteristics of 4A must be within 2% or 1 degree the 3B characteristic. More than a single 4A characteristic and the stone cannot grade 3A. An overall class 4 girdle thickness cannot grade 3A overall. An overall girdle thickness is NOT determined by a single thin or thick area of a girdle. "Overall" has a meaning equivalent to "the major portion." (crown angle degree rounds only)

3B grade:
As stone may be all 3B or 1A thru 4B. Any single characteristic of grade 4B must be within 2% or 1 degree of the 4A measurement. Only one class 4 characteristic permitted. Stones with class 4 extremely thick or extremely thin over all girdles may not be graded overall 3B. (crown angle degree rounds only)

4A grade:
A stone may be all 4A or 1A thru 4B. Only two 4B characteristics are permitted at most. (crown angle degree rounds only)

4B grade:
Is all 4B or may be any combination from 1A thru 4B. Stones with more than two 4B characteristics are automatically 4B.
 
Thank you for the in-depth explanation. After review, I am considering the following diamond for purchase:

1.48 ct, round

7.58 X 7.45 X 4.29 mm
slighly thin to medium girdle (not sure what this means)
32.9 avg crown angle and 11% crown height
57.1% pavilion depth, 63% table and 43.3% pavilion depth
AGA cut class - 2B
Fluoresence - none
appr GIA color - H
appr GIA clarity - VS2

is this a decent stone and what would be a price to buy it at considering rapoport values. Would it be graded the same by GIA, hence the same price range?
 
Again, it is a different variety of a non-ideal make. Again, it may look nice to you, but the value proposition is similar to the other. It does have larger visible size going for it.
 
What are the ideal parameters for this kind of diamond and giving these parameters how much off rapoport is it worth paying?
 
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