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Best way to measure the quality of a Princess cut?

netcbc

netcbc

Rough_Rock
Joined
May 22, 2010
Messages
65
Hi all I am in Toronto, I''m looking to ensure I''m getting a good deal but also a good quality stone.

I''ve selected GIA certed diamond, unfortunately it''s no longer online as it has been reserved.

I have it hwgem.com for an appraisal and to get an ASET scan, anything else I should try to do?

Shape Princess
Carat Weight 1.85 ct
Color F
Clarity is vs2
Depth % 74.2 %
Table % 68.0 %
Symmetry % Very Good
Polish Very Good
Dimensions 6.77x6.52x4.84 mm
L/W Ratio 1.04

Thanks!
 
Including an impartial expert eye will give you more than we can offer here. Suggest you ask specifically about the VS2 grade @ that carat weight.

It sounds like you'll be in an educated place with cut assessment. Harold passed away last year but his firm continues use of the AGS membership credentials - I would think that means they'll provide and discuss ASET (at a minimum) and may even be licensed to run AGSL's PGS software for the diamond; the finish grades will exclude it from a provisional AGS0 overall, but that does not take anything away from the light performance result.
 
Date: 5/25/2010 2:26:27 PM
Author:netcbc
Hi all I am in Toronto, I''m looking to ensure I''m getting a good deal but also a good quality stone.

I''ve selected GIA certed diamond, unfortunately it''s no longer online as it has been reserved.

I have it hwgem.com for an appraisal and to get an ASET scan, anything else I should try to do?

Shape Princess
Carat Weight 1.85 ct
Color F
Clarity is vs2
Depth % 74.2 %
Table % 68.0 %
Symmetry % Very Good
Polish Very Good
Dimensions 6.77x6.52x4.84 mm
L/W Ratio 1.04

Thanks!
Click to expand...
I agree with Sir Jon''s advice, In addition I''d ask for a photographed ASET and Idealscope and the output of a sarin in a .srn file format as well as the full AGS-PGS report . If you post the .srn file in the forum someone may be willing to import into Diamcalc and convert it to a .gem file where we can view it in various lighting conditions including ASET black 30.
 
Date: 5/25/2010 2:42:13 PM
Author: John Pollard
Including an impartial expert eye will give you more than we can offer here. Suggest you ask specifically about the VS2 grade @ that carat weight.

It sounds like you''ll be in an educated place with cut assessment. Harold passed away last year but his firm continues use of the AGS membership credentials - I would think that means they''ll provide and discuss ASET (at a minimum) and may even be licensed to run AGSL''s PGS software for the diamond; the finish grades will exclude it from a provisional AGS0 overall, but that does not take anything away from the light performance result.
Click to expand...
Ditto John, also ask for a detailed photograph as well as ASET and a Sarin or Helium scan if possible. Post all the info here then we can go from there.
 
If I were buying a Princess Iwould look for AGS0 princess cuts as they have been graded for cut quality.
 
Great advice given so far.
AGSL does grade Cut Quality on Princess cuts- which is one way to make sure you get a really well cut stone.
The AGSL cut grade is a bit controversial, although most experts would agree that the AGS 0 Cut grade stones are very well cut.
The controversy is that there are other styles of princess cuts - which are well loved by many- that would be downgraded under the AGSL system- primarily more shallow stones ( say depth under 69%) with larger tables ( larger tan 68%). It's unlikely you'll even find stones cut like this with AGSL reports- but ou've already indicated a preference for GIA- which I agree with.
Both looks can be very pretty.

Looking at stones in person is a very good idea, if at all possible.
 
Date: 5/26/2010 1:53:52 PM
Author: Rockdiamond
Great advice given so far.
AGSL does grade Cut Quality on Princess cuts- which is one way to make sure you get a really well cut stone.
The AGSL cut grade is a bit controversial, although most experts would agree that the AGS 0 Cut grade stones are very well cut.
The controversy is that there are other styles of princess cuts - which are well loved by many- that would be downgraded under the AGSL system- primarily more shallow stones ( say depth under 69%) with larger tables ( larger tan 68%). It''s unlikely you''ll even find stones cut like this with AGSL reports- but ou''ve already indicated a preference for GIA- which I agree with.
Both looks can be very pretty.

Looking at stones in person is a very good idea, if at all possible.
Click to expand...
Rd,

AGS uses light performance ray tracing to determine light performance, not proportions to grade princess cuts.

Final Cut grade = Maximum(Sum(Brightness ,Dispersion ,Contrast ,Leakage ,Weight Ratio, Durability ,Tilt), Girdle, Culet, Symmetry, Polish)

Just because your standards for what is "Ideal" or "pretty" are wider/lower than their Ideal 0 grade doesn''t mean that its a controversial standard.

A consumer should decide if they just want a "pretty" stone or if they want one of the "most beautiful" diamonds like many that attain the AGS ideal standard.

If a consumer wants the latter latter than your comments aren''t very helpful, if the consumer wants the former than they don''t need Pricescope, they can walk into ABC store and pick out their favourite average princess cut graded by GIA by going from jewelry store to jewelry store and just choose with their own eyes without asking any of us for advice.

Show me a princess that doesn''t achieve AGS ideal grading that is "more beautiful" in a category they don''t consider in their cut grade and we''ll have something to discuss, otherwise you are just saying its okay for you and the consumer to have a lower standard for what is considered beautiful.
 
GIA doesn’t ‘measure the quality’ of the cutting on princess cuts at all, and AGS doesn’t do it using the information that you’ve provided. Your appraiser should be able to help you out and, in my opinion, that’s the best way to approach it. When you pick it up, read the report and ask lots of questions. It's hard to write a catch-all report that says everything that every potential client will want to know. If you aren't meeting in person with the appraiser they are, to an extent, guessing about what you want so don't be shy about asking questions. It's part of what you're paying them for.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
Since AGSL graded princess cuts are extremely rare, ccl may be correct that I made assumptions about which stones would qualify for their top grade. I could not find any info on the princess cut grade on the AGS site.
Based on what I've seen, the AGS 0 stones had smaller tables, associated with greater crown height- which impacts overall depth.
Which is a better cut- or a more beautiful stone?
One can't really "legislate" beauty.

Hopefully the OP will be able to use all the comments made to their advantage.

ETA- Neil- I agree that a qualified appraiser can assist in determining if a stone is considered well cut.
But I think it's super important to mention that an appraiser's opinion has limited value in determining if the consumer loves the stone. That is to say: An appraiser can make comments about how well a stone is cut- but that does not necessarily mean the consumer will love it.
 
David,

It’s not published in a way to make them especially easy to digest but here's the cutting guidelines for AGS Princess cuts in terms of the various dimensions and facet angles. The process also entails a personal inspection for symmetry, polish and a few minor details but this is the heart of the system.

The original question was about measuring the quality of the stone. Love is not a unit for that. Possibly cut grade isn't either, but I think it's what they were asking about. I agree that people should buy what they love, regardless of what AGS, GIA or any of us have to say about the matter.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
I'm with Neil here. Harold Weinstein Ltd is a capable outfit. They should be able to help you best. Their AGS Member credentials imply that you'll get a robust overview covering several landscapes and interpretations of pedigree. Write down any and all questions you have - they should gladly answer.

And while it might be interesting to return for comment on pictures/scans you may get from the appraisal, no one here can possibly give you more meaningful information from those things than a capable expert can with the diamond in his/her hands.
 
I agree that consulting a qualified appraiser is a great idea.
But I disagree that "love" is not a part of what constitutes great cut- for each of us.

After all, if a person did not love the stone, why spend the money.
It''s a far more difficult parameter to measure objectively, for sure.

I''ll try to find time to look over the AGSL documentation, but would you ( John or Neil) say it''s accurate that AGS favors stones with a tables smaller than 70%?
 
Are EGL love grades softer than GIAs?
 
If one wanted the "best cut" possible, then it''s pretty much agreed that some sort of AGS0 or GIA EX cut grade Round Brilliant will be, technically, the "best cut"

Preference comes into play as soon as we move from looking only at numbers, or stats based on light return and look at actual diamonds.
 
I didn’t say that love isn’t part of what constitutes a great cut for people. Love is the point, but it’s not what constitutes a great cut grade.

The guidelines go all the way up to 80% tables and can still get an AGS-0 cut grade. Most of the cutters who are producing stones aim for the smaller size tables because of personal preference and because the target is more forgiving. Going through the extra trouble to cut a 0 and then having it come back as a 1 or worse for some unexpected reason is a serious bummer for them.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
Date: 5/26/2010 3:33:21 PM
Author: kenny
Are EGL love grades softer than GIAs?
Click to expand...
EGL is in Europe and we all know about them. Then again, GIA is in CALIFORNIA.
23.gif


Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
Thanks for the great info Neil.
I agree- if a cutter misses the AGS0, they are stuck having to then spend more money on a GIA report. Bummer.

I see so very few fancy shaped stones with AGSL reports- but I''d love to see more.

Since I love diamonds so, I do place the emotional aspect pretty high on the scale.
 
Date: 5/26/2010 3:57:10 PM
Author: Rockdiamond

-snip- if a cutter misses the AGS0, they are stuck having to then spend more money on a GIA report. Bummer. -snip-
Click to expand...
Cutting to AGS0 rules will generally produce a lower yield in terms of weight and is more time consuming in terms of labor and the whole point for the cutters to put up with this is to get a premium price at the end. Double lab fees is just adding insult to injury.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
Date: 5/26/2010 3:27:22 PM
Author: Rockdiamond

...would you ( John or Neil) say it's accurate that AGS favors stones with a tables smaller than 70%?
Click to expand...
Yes - and GIA and AGSL both favor round brilliants with tables smaller than 63%.

"Hey! I know people who like RBs with 65 or 70% tables..." Are they wrong to like them? No way. But it's fair to say that modern grading metrics note that some visual components may be reduced in such diamonds. Fine. Viva le difference.

GIA doesn't have a metric for princess cuts. When it comes out I'll be surprised if the upper threshold for table size differs much from AGSL, the old AGA charts and current ray-tracing studies; at or near 70%. Remember that AGSL and GIA are within 1% on the upper end for round brilliant table size allowed (Ideal/Ex): In fact candidates for AGS0 range from 47-61% while candidates for GIA EX are limited to 52-62%. AGSL allows more table sizes but has fewer configurations possible since their metric follows the inverse c/p cutter's line more closely.

Back on point: AGSL will award 0 in light performance if the diamond meets minimum requirements for brightness, dispersion & contrast without too much light loss through the pavilion, regardless of table size. Logically at some point increasing the table size can prevent top dispersion/contrast. In RBs the top number (AGSL and others) is around 63%. In Princess cuts (AGSL and others) that threshold is around 71%.

"Hey! I know people who like PCs with 75% or 80% tables..." Are they wrong to like them? No way. But it's fair to say that modern grading metrics note that some visual components may be reduced in such diamonds. Fine. Viva le difference.
 
Thanks John- and Neil.
I think that introducing rounds into the conversation will highlight a few differences.
The tolerances of table and depth are far more limited on rounds.
For example, I don''t know of anyone who loves rounds with tables above 63%, as a rule. But larger tables on princess cuts- even with shallow crowns- can produce some stones that are quite pretty.
 
Date: 5/26/2010 3:57:10 PM
Author: Rockdiamond
Since I love diamonds so, I do place the emotional aspect pretty high on the scale.
Click to expand...

I so love diamonds so, which is why I love tools like HCA, IS, and ASET to help me pick one I'll love without the luxury of being able to see it first.

Since I'm assured of a better-performing diamond these tools contribute to, rather than take away from, the emotional and romantic experience when you are buying sight-unseen online.
 
Luckily, I get to see all the diamonds we buy in person.
If you were to do it that way, Kenny, you might find that you loved some stones that did not score well on HCA, or produce and IS or ASET that you liked. "Performance" and diamonds- that's one we'll have to agree to disagree on as I don;t feel the term is applicable.


But we agree- emotion does play a part. Therefore if you like doing it the way you do, it's not up to anyone to say you're wrong.
 
Date: 5/26/2010 4:53:19 PM
Author: Rockdiamond
If you were to do it that way, Kenny, you might find that you loved some stones that did not score well on HCA, or produce and IS or ASET that you liked.
Click to expand...

If buying online why bother taking the risk since the tools identify diamonds we know are well cut?

Since you say diamonds rejected by the tools are so beautiful you'll have no trouble selling them to your walk-in customers.
If you don't get walk in customers then get with the program, join the 21st century, and stop buying the rejects.
 
Thanks for the thoughtful advice Kenny!
I don;t know who the "we" you refer to is, but I'm sure those in your group are very happy doing things the way you suggest.
There are always going to be other ways of selecting great cut....that may produce results contrary to your methods
 
Date: 5/26/2010 5:08:30 PM
Author: Rockdiamond
Thanks for the thoughtful advice Kenny!

I don;t know who the 'we' you refer to is, but I'm sure those in your group are very happy doing things the way you suggest.

There are always going to be other ways of selecting great cut....that may produce results contrary to your methods
Click to expand...

Online purchases are increasing.
Tools support that method because buyers cannot see the diamond.
Diamonds rejected by the tools will be less in demand.

Go ahead and keep defending the diamonds that are rejected.
You have the right to drive on the wrong side of the road with your business.
Just don't be surprised by the bumpy ride.
 
Kenny- Clearly, you have some sort of agenda- but I honestly don''t feel it''s at all relevant to this conversation.
 
My agenda is good cut.

Everyone has an agenda.
 
Yes, and as a professional, I am not anonymous. NO one knows who you are, or why you''re here constantly attacking.
I LOVE great cut on stones.
Hopefully, it''s a positive aspect to this forum having different professional viewpoints contributed.
 
David stop playing the victim card, I''m not attacking you.
No need to twist things around again and make it personal.

It is you who who attacks good cut, over and over, year after year, in new and surprising ways, from every angle possible.
You get into arguments with most every supporter here on PS of good cut and the tools.

It is astonishing that you don''t realize you come across as a diamond seller defending poor cut.
 
Hi all, wow this thread really took off, I'm meeting with HW tomorrow, I'm not exactly sure what to ask though lol..

I guess what got me started was seeing the youtube video from GOG of 2 identical looking princess cuts however one sparkled way more then the other.
http://www.youtube.com/watch?v=FIGufTup_F8&feature=related

I had thought a ASET image would be sufficient but seems to be a lot of other variables now?

With the details so far, how does the stone look? I'll be trying to get ASET soon but won't be able to get the sarin or idealscope.
GIA Certed
Shape Princess
Carat Weight 1.85 ct
Color F
Clarity is vs2
Depth % 74.2 %
Table % 68.0 %
Symmetry % Very Good
Polish Very Good
Dimensions 6.77x6.52x4.84 mm
L/W Ratio 1.04
 
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