Is 60/60 a bad proportion for a round diamond- can we trust a GIA "EX" cut grade?

[Rockdiamond]

I''d say most people spending the kind of money we''re talking about here would have looked at diamonds.
Hopefully DF can give usmore details.

My point is that what you are calling "leakage" which sounds like a negative connotation, others might see as contrast, and actually find attractive.

 

[risingsun]

Date: 2/18/2009 6:10:21 PM
Author: MissGotRocks
GIA excellent cut graded stones have more variance in them. Many people have bought them and loved them - depending on how the angles work. I don't think anyone is trying to say that they are all bad - just that they require further interpretation.

I had a 60/60 stone graded by GIA before their cut grading came into play. It was a white, brilliant stone. I was looking to trade it up to a larger stone - it was at the 2 carat mark. When I started reading about H&A and AGS0 stones, I really thought it was some sort of marketing gimmick. Then I went to see an ideal cut stone. I ended up trading that 60/60 stone for a 2 ct. AGS0 ideal cut stone. The difference - to me - was night and day. Finally I found that 'sparkle' that I had been missing for so long. Then I began reading and learning about crown/pavillion angle relationships and started understanding a bit about how they worked - or didn't. I eventually traded up to a 2.22 AGS0 stone - and I've been nothing but thrilled with the performance. The edge to edge brillance these ideal cut stones provide is is just a different look to my eyes than the 60/60 stones - and I saw alot of them as well. Who knows what the future holds in terms of diamond cutting? I look forward to new and different as well although I think today's ideal cuts will always hold a place in my heart so I understand you feeling the way you do about your concept of a beautiful stone. The 60/60's and today's version of an ideal cut stone are two different animals. Once you have pointed out the differences, you need to step back and let people make their own decisions.

Many of us have spent many hours here trying to learn and absorb all we can about the particulars of diamond cutting and grading. Certainly doesn't make us experts - it just gives us knowledge to make an informed decision when buying. While I appreciate you presenting the virtues of another cut, it doesn't and won't cancel out what many of us have seen and experienced with our own eyes and wallets.

You can only present information to people - what they choose to do with it is another matter. Honking the horn harder doesn't make the information more acceptable or believeable. It's just a different point of view to consider - then you have to step back and let people decide for themselves what they want. We don't necessarily champion our group of experts here - we have just watched and learned and seen the fruits of what they say delivered. The proof is in the end result.

I think you have received some very good advice. You have made your position quite clear. Many of us prefer the diamonds offered by Brian Gavin, Paul Slegers, Maarten DeWitte, Gabi Tolkowsky and others. It's not only Garry and Serg who have this opinion about ideal cut diamonds. You need to respect our opinions, just as you want us to respect yours. Honking your horn louder will not serve you well on this forum.

 

[Rockdiamond]

Marian, sorry if this thread upset you in any way.
Since this is a forum about diamonds, it would seem that discussing them is the essence. I started this thread so as not to "thread-jack" someone asking for advice. It is not my intention to "honk any horns" rather to discuss this so that we''re not infringing on someone asking for advice. A conversation where everyone agrees is great- but having alternative viewpoints also seems interesting to many. Are the only choices to agree, or simply keep my opinions to myself?

In terms of "proof" once I did start the thread, someone immediately came out of the woodwork to state that he felt he''d bought a bad diamond based on what people had written here. Thankfully others came on to confirm that was not the case.

It is interesting that people get very upset at even the mention of other ways of looking at cut.
I''m not saying anything at all negative about any of the people you mentioned, or their diamonds.

But there have been many negative comments about "Steep Deep" diamonds- and also people stating flat out the GIA''s cut grade is not to be trusted.
GIA being what it is to this industry, it seems to be a valid conversation for those interested in buying diamonds, or learning about them.

 

[John P]

Date: 2/18/2009 7:33:45 PM
Author: MikeRato1

john, i was never told i bought a crap diamond, nor did i say someone told me that, i just said that ''i feel'' that way. the main reason i feel that way is because i value garys opinion alot and thats the reason i was using his hca tool during my search, and when i say ''during'' i mean right there in front of the sales associate. i understand that alot of these forums are opinions and i greatly appreciate everyones (expert or not) so if there is a topic that i do not agree with i just do not take part

Ah - ok. So when you said "here''s the crappy numbers" no one from PS had ever said that to you? Huge relief. It''s a bummer you were under that impression at all. I wish you''d posted the details at the time because I suspect your feelings would have been assuaged then, especially the way you describe your journey.

The HCA is a valuable tool but does overprotect in that 2.0-2.5 area without added information. I can''t think that''s a bad thing Mike, since there are diamonds in that zone which, because of imprecision, variations, digging, etc., are not in the class yours is in. I hope this thread has shed some light.

 

[John P]

Date: 2/18/2009 7:13:28 PM
Author: Rockdiamond

John- thank for posting those!

The second 60/60 is exactly the type of stone I'm talking about.
Could you do a side view of that one?

I understand why you want the side views. Picking a few tenths of a degree in avg angle is pretty tricky that way, especially on stones with variance, but I admire your courage. I'm going to post a slew of them for you in a minute.

Date: 2/18/2009 8:57:57 PM
Author: Rockdiamond

The other aspect to remember is that if there is a clear detriment to the appearance of the stone, a cutter would be foolish to follow that course on purpose.
Even though I feel that many buyers are safe with a GIA EX cut grade- I also make sure to remind people to get detailed photos, videos, and a money back guarantee.
If the stone is bad looking, the GIA cut grade isn't going to satisfy the buyer.

Oof. That's a little utopian David. If you multiply even 1% more weight retention over a million carats of production you get hundreds of thousands of dollars profit that would otherwise wind up as diamond dust. Pushing that steep/deep area is not going to get better, it's going to get worse. Now that GIA's EX has been out for three years more big manufacturers are learning to game the system.

Dealer education continues to be a problem too. Forget that dealers can stock GIA EX which might be problematic away from their spotlights and not even know it. I did a random walk-by of a jeweler near our Dallas dealer yesterday and was shown a 60T-63.6%D round (GTL report from 2001). She told me it was an EX cut by today's standards because P&S were both EX.

 

[John P]

David, here are nine profile views of diamonds at or near 60-60. All of them are GIA EX. They range from brilliancy properly returned to the eye that would earn AGS0 to severe enough under-table & girdle leakage to be penalized to AGS6 when ray-traced. Based on these views and the fact that all are GIA EX, which do you suppose you could recommend?

 

[risingsun]

David~I''m not upset with you. I am just saying that there are other points of view. A number of these views come from vendors/cutters who are well respected in the field. When buying a diamond online, many of us want to be careful to choose a stone with the best parameters--as we believe them to be--and use all the tools available when making a decision. I would like to know what kind of experience you have had with ideal cut diamonds, as many of us define them on this forum. Have you had the opportunity to really examine them, live with them and see how they perform? I think it would be worth it

 

[John P]

Date: 2/18/2009 8:57:57 PM
Author: Rockdiamond

Part of this discussion is about what is called 'Steep Deep'- that is to say a diamond graded EX cut grade by GIA but not thought to be deserving of the 'Ex' cut grade. I'm paraphrasing what I have read here- steep deep what you need to watch out for in GIA EX cut grade.
What if, just for the sake of conversation we can say that not all people would see the phenomenon described as negative in the viewing. Say enough people actually picked what is described as 'steep Deep' to be included in GIA's EX cut grade.

It would not be in line with their other categories David. Consider color, where most people cannot differentiate between D and E, yet that division (and premium) exist. It's even more pronounced in clarity and finish, where no human can differentiate between the top grades, yet the division (and premium) exist.

Now take cut, where you have a top grade where brilliancy is allowed to be compromised at the steep/deep end due to leakage (leakage...not contrast where those facets will light up once the diamond is tilted). Now you have some round BRILLIANTS in a lower division of brilliancy, but at the same grade. That is not in-line with the standards of visibility in grading for which GIA earned their reputation.

By the way I am a HUGE fan of GIA and very proud of the diploma on my wall. The fact that they launched a cut grade in 2006 still has me standing on a chair, lighting a match and sounding my air-horn. The system has room for improvement, but so did the AGS system when it was introduced (still does). It has undergone revisions as research and technology have improved and I am sure GIA's system will evolve and improve as well. I don't believe any system is perfect, which is why I want a number of cross-references and data if I am asking to comment on the pedigree of any diamond I don't have in-hand.

 

[Rockdiamond]

Marian, thank you for that.
I really don''t want to upset anyone!

I have had extensive personal experience with AGS O cut grade"Ideal Cut" as well as many other diamonds with GIA EX cut grades.
We have made jewelry with these stones, and seen how they perform once set.
I''ve looked at a tremendous amount of GIA EX cut grade diamonds under just about every conceivable lighting situation. I have yet to see even one that would be considered "poorly cut".

I''m not saying I don''t love the smaller tabled stones- I do.
I love a slightly larger table, slightly shallower diamond more, but that''s my personal taste.
Both are beautiful.


Let me again state very clearly that I admire and respect John, Paul, and others who are working with what they consider to be the best cut diamonds.
But it also bears repeating that many experienced diamond people feel that "ideal cut" has more to do with shrewd marketing than actual beauty if we''re comparing to other well cut diamonds. I''m not saying this is a fact, but it is an opinion held by some of the top people in the diamond business.


Now let me look at the diagrams John has so graciously provided.

 

[John P]

Date: 2/18/2009 8:57:57 PM
Author: Rockdiamond

What if, just for the sake of conversation we can say that not all people would see the phenomenon described as negative in the viewing. Say enough people actually picked what is described as 'steep Deep' to be included in GIA's EX cut grade.

I wanted to come back to this, as I think it's a key point of departure. After all, what is 'taste' versus 'quality?'

Some people like warmer colors. Cool, we can point them to those grades.
Some people like eye-visible inclusions. Cool, we can point them to those grades.
If someone likes reduced brilliancy we can reserve VG and lower cut. But time and research, far before GIA was around, has shown that most people want a brilliant to return as much light as possible to the eye...

BRILLIANT CUT 101

We're all familiar with what constitutes diamonds cut for best brilliancy versus too shallow or too deep. Why? Just Image-Google 'diamond cut light' and you get these familiar graphic (I disagree with the term 'Ideal' in some of these. No matter, it's the optical concept that's relevant).

What do these all shows? That there are optimum angles for brilliancy. Angles too shallow or deep result in reduced brilliancy.

http://www.arthursjewelry.com/images/articles/diamond_light.jpg
http://www.supergemsgroup.com/index-new.asp?section=prelog/Diamond_Info&action=diamond_4c_cut
http://rhinodiamonds.com/images/diamond_cut2.jpg
http://www.goldsmithlf.com/extra/diamondcut2.jpg
http://www.arainjewellers.com/i/4cs1.jpg

GIA includes the concept in their online tutorial and in formal education coursework.

http://howtobuyadiamond.gia.edu/TRA_ChallengeFrameSet.htm

So the universal idea of a BRILLIANT cut is that it returns light to the viewer's eye, resulting in brilliance.
Leakage (deep) and shadow (shallow) reduce brilliancy. Such diamonds are not doing the best job as BRILLIANTS.

Here's the same fundamental graphic along with ASET and IS images. Angular spectrum shows clearly that the shallow diamond would have reductions in brilliancy due to shadow and the deep diamond would have reduced brilliancy due to leakage. Neither is doing its job as a BRILLIANT.

This is why IS and ASET images are helpful here. They show clear correlations for brilliants to these age-old graphics.

 

[John P]

Date: 2/19/2009 4:40:03 PM
Author: Rockdiamond

I'm not saying I don't love the smaller tabled stones- I do.
I love a slightly larger table, slightly shallower diamond more, but that's my personal taste.
Both are beautiful.

Let me again state very clearly that I admire and respect John, Paul, and others who are working with what they consider to be the best cut diamonds.
But it also bears repeating that many experienced diamond people feel that 'ideal cut' has more to do with shrewd marketing than actual beauty if we're comparing to other well cut diamonds. I'm not saying this is a fact, but it is an opinion held by some of the top people in the diamond business.

Now let me look at the diagrams John has so graciously provided.

Thanks David. I appreciate it. I hope you don't mind a point of order... You routinely use "Ideal" to describe near-Tolkowsky stones but the term is somewhat outdated. As shown in this thread, diamonds of the 60/60 make can earn the "Ideal" grade (AGS0). When you say "smaller tables" that serves to a degree but those makes can also stray away from the near-Tolks you seem to be implying.

Since 60/60, near-Tolk, high-crowned and shallow makes can all fall into the "Ideal" category...and considering the abuse the word ideal receives worldwide...you may understand why some experts choose to use the more accurate "near-Tolk" term when referring to round brilliants with table and angles near-Tolk.

 

[Rockdiamond]

Date: 2/19/2009 3:58:09 PM
Author: John Pollard

Date: 2/18/2009 7:13:28 PM
Author: Rockdiamond

John- thank for posting those!

The second 60/60 is exactly the type of stone I''m talking about.
Could you do a side view of that one?

I understand why you want the side views. Picking a few tenths of a degree in avg angle is pretty tricky that way, especially on stones with variance, but I admire your courage. I''m going to post a slew of them for you in a minute.

Date: 2/18/2009 8:57:57 PM
Author: Rockdiamond

The other aspect to remember is that if there is a clear detriment to the appearance of the stone, a cutter would be foolish to follow that course on purpose.
Even though I feel that many buyers are safe with a GIA EX cut grade- I also make sure to remind people to get detailed photos, videos, and a money back guarantee.
If the stone is bad looking, the GIA cut grade isn''t going to satisfy the buyer.

Oof. That''s a little utopian David. If you multiply even 1% more weight retention over a million carats of production you get hundreds of thousands of dollars profit that would otherwise wind up as diamond dust. Pushing that steep/deep area is not going to get better, it''s going to get worse. Now that GIA''s EX has been out for three years more big manufacturers are learning to game the system.

Dealer education continues to be a problem too. Forget that dealers can stock GIA EX which might be problematic away from their spotlights and not even know it. I did a random walk-by of a jeweler near our Dallas dealer yesterday and was shown a 60T-63.6%D round (GTL report from 2001). She told me it was an EX cut by today''s standards because P&S were both EX.

John,
Yes, there''s PLENTY of dealers misinforming a lot of consumers. It''s a huge problem, on that we agree wholeheartedly.
In terms of big manufacturers "gaming the system", we disagree.
I base my opinion on my own personal experience with GIA EX cut grades. I have not seen a badly cut EX cut grade- and to be completely honest, the examples provided photographically here don''t seem to clearly demonstrate a problem.

One of our closest connections is with a cutter who''s definitely in the top 5 in terms of number of stones/carats submitted to GIA. These people are HUGE.
They feel GIA is extremely tough- that many stones downgraded to VG are actually deserving the EX cut grade. If we take the suggestion that the cutter has no interest in making a nice diamond, only to squeeze out all the profit they can from the rough, then what the cutter says is meaningless.

But if you look at the pragmatic side of this, the cutter needs to produce diamonds that will sell- and stay sold. If a "Steep Deep" is going to show a lot of ill affects once the buyer walks out of the store, it''s going to to get returned. That''s going to cause problems for the store, the cutter- all the way down the line.
If a GIA EX cut graded "Steep Deep" is as bad as it''s made out to be, wouldn''t those stones sit in stock- or come back as returns repeatedly?
Wouldn''t that in itself be a problem for the cutters- especially if their sole interest was profit- at the expense of everything else......


My experience is that the best cutters are very interested in producing a well cut stone. But if we stipulate that there are bad cutters out there ( which makes sence, as there''s a small percentage of "bad people" in every field) - once we include GIA into the equation, and we no longer have to take the cutters word, it seems that the consumer is the winner.
Unless of course GIA is passing badly made stones off as "EX" cut grade.
But I strongly disagree with that one.......

 

[MikeRato1]

Date: 2/19/2009 3:51:05 PM
Author: John Pollard

Date: 2/18/2009 7:33:45 PM
Author: MikeRato1

john, i was never told i bought a crap diamond, nor did i say someone told me that, i just said that ''i feel'' that way. the main reason i feel that way is because i value garys opinion alot and thats the reason i was using his hca tool during my search, and when i say ''during'' i mean right there in front of the sales associate. i understand that alot of these forums are opinions and i greatly appreciate everyones (expert or not) so if there is a topic that i do not agree with i just do not take part

Ah - ok. So when you said ''here''s the crappy numbers'' no one from PS had ever said that to you? Huge relief. It''s a bummer you were under that impression at all. I wish you''d posted the details at the time because I suspect your feelings would have been assuaged then, especially the way you describe your journey.

The HCA is a valuable tool but does overprotect in that 2.0-2.5 area without added information. I can''t think that''s a bad thing Mike, since there are diamonds in that zone which, because of imprecision, variations, digging, etc., are not in the class yours is in. I hope this thread has shed some light.

john, i was just being sarcastic when i said "crappy" but when i punch the numbers in the hca thats what it tells me, and i trust what gary does, i mean he created that to help customers like myself make a smart decision. now if i was not so unsure about buying such an expensive diamond over the internet that would have been the main tool i would have used, and i am willing to bet i would have got a perfect looking stone. but there was something about the experience about bring my future wife into a local store and us picking out one together, that was what she wanted and that was the diamond that she wanted, and there was no way i could say no to that

something that we talked about at the store was how some cutters might cut to save weight but something she brought up that i had never thought about is what if i had never found pricescope, i would have walked into any store and they could have shown me a gia very good stone, had i not have done my homework i would have thought that "very good" was "great"! so i guess now im wondering if cutters cut to save weight why dont they save even more weight by only making the cut "very good" then wouldnt non-pricescope b&m customers get a bigger stone for the money? or am i thinking too much?
anyway, sorry if i made this thread any more confusing by adding my experience

 

[purrfectpear]

Maybe we just need to define the word "bad" and "poor".

It sort of sounds that bad and poor must be fairly egregiously awful when you use it David (aka "I don''t think there are bad cutters, or I have yet to see even one GIA EX that would be considered poorly cut.")

I think that John and some of the rest of us are saying "less than optimal" rather than egregiously bad or poor.

I don''t think there are bad cutters as much as there are cutters who are willing to sacrifice optimal performance to eek their stones in "just under the GIA wire" so to speak. They''ll sacrifice performance for weight. That doesn''t make them bad guys (it sounds like on that we agree?) it makes them smart cookies (but at the possible expense of the best diamond). Ditto for GIA EX grades. They aren''t poorly cut to you, but we''ve seen some that are definitely not as well cut as expected. Maybe we don''t agree on the definition of poor? Poor doesn''t have to be the worst.

 

[Serg]

Date: 2/19/2009 2:22:40 PM
Author: Rockdiamond
I'd say most people spending the kind of money we're talking about here would have looked at diamonds.
Hopefully DF can give usmore details.

My point is that what you are calling 'leakage' which sounds like a negative connotation, others might see as contrast, and actually find attractive.

David,

re:My point is that what you are calling 'leakage' which sounds like a negative connotation, others might see as contrast, and actually find attractive.


Pro: leakage could be positive and give Good contrast, specially for Fire. But I saw good such examples only for fancy cuts
Con: “Dead ring” for RBC is not good even for contrast. Such ring psychologically destroy classical RBC pattern but do not give any compensation in Fire,…

Pro and Con: Diamonds between H&A&AGS0 and “Dead ring” are not so bad like you can imagine from Cyclops point of view( IS, FS, ASET).

Human has stereo vision what increase range nice diamonds near H&A line. These diamonds have less LR but better Fire ( and Fire contrast). It is issue about TASTE and FASHION .

Most PS members BELIEVE in H&A only. FASHION could be different in next 5-10 years

RBC Is not the end of diamond cut evolution. I have quest to proof it

 

[Rockdiamond]

Date: 2/19/2009 4:02:20 PM
Author: John Pollard
David, here are nine profile views of diamonds at or near 60-60. All of them are GIA EX. They range from brilliancy properly returned to the eye that would earn AGS0 to severe enough under-table & girdle leakage to be penalized to AGS6 when ray-traced. Based on these views and the fact that all are GIA EX, which do you suppose you could recommend?

Courage or stupidity....sometimes it''s a fine line John.....heheh
As you''ve mentioned trying to assess a diamond based only in a CG side view is difficult at best....but here goes...
#1 looks to have a thick girdle, and heavy crown.
#2 also looks thick in the girdle although the crown and pavilion angles look nice.
#3 seems thin at the girdle
#4- not bad
#5 seems to have heavy crown
#6 girdle looks a little heavy, but not bad otherwise
#7- looks about the best of the bunch
#8 - seems to have steep crown angles
#9- also not bad, but the girdle seems a bit thin


I would not be willing to recommend any diamond without speaking to the potential buyer to see what they are looking for, and also having a look at the actual diamond.
IN terms of these diamonds getting EX cut grade- I have no doubt John knows exactly how to use the diamondcalc, and plug in numbers to assure that the simulation would in fact get a GIA ex cut grade.
But the exercise is still an academic one unless we''re comparing actual diamonds, and can examine them to see what the actual face up is.
IMO the charts posted showing light path through a diamond are overly simplistic, and the CG ASET and IS images are also non conclusive in relation to real diamonds, and how they look in person.


Also a great point about the usage of the word "ideal".

The term has been so horribly abused so as to be almost meaningless at this point.
I suppose I use it for lack of a better word- but "Near Tolk" sounds reasonable!

 

[Rockdiamond]

Piurrfect- we agree on something- the World feels right about now!!

I agree as well that the terms used are critical.
As Serg pointed out, what some might see as a "ring of death" in an ASET or IS might look quite different viewed real life with two eyes.

"They aren''t poorly cut to you, but we''ve seen some that are definitely not as well cut as expected. Maybe we don''t agree on the definition of poor? Poor doesn''t have to be the worst."

Correct Purrfect- but the other side of the coin is that what some here on PS might consider not to be well cut, other knowledagable diamond people would consider to be well cut.

 

[Serg]

Re: So the universal idea of a BRILLIANT cut is that it returns light to the viewer''s eye, resulting in brilliance.

It is just one task for Diamond Cut. It is important task, but there are other important tasks for diamond Cut:

1) Catch light from even single light source in the room and redirect it to eye( it is not same task about maximum LR or even Brilliancy )
2) Create Great Fire
3) Redirect light( reflect source light) by different parts of pattern
4) Sparkling
5) Unique for you, Best specially for you
Be different, be Smart

 

[John P]

I'm waiting on your side view judgments David.

Date: 2/19/2009 5:06:16 PM
Author: Rockdiamond

If a 'Steep Deep' is going to show a lot of ill affects once the buyer walks out of the store, it's going to to get returned. That's going to cause problems for the store, the cutter- all the way down the line.
If a GIA EX cut graded 'Steep Deep' is as bad as it's made out to be, wouldn't those stones sit in stock- or come back as returns repeatedly?

"As bad as it's made out to be" may be different to you and me David. When a guy drops to his knee and opens the box I doubt a girl will say "no" because it has a 41.8 pavilion angle - any more than she'd complain about the lab where it was graded. How about this question: Do you see everyone with EGL-Israel graded F-VS1s inevitably discovering that they may be closer to H-SI1? Are people on a mission to assess the color and clarity decisions they made post-proposal? Or do you imagine they trusted their jeweler to deliver the best quality, have no idea and never will about the soft color and clarity they received?

Pricescope is full of joyful conversations about nuances in quality seen only in a romantic restaurant, or under a tree, or by a pond. You're right that most people will not take note of the leakage in a less brilliant steep/deep. In fact, I feel only a single digit % of the world's brilliants are cut to optimum quality, regardless of make. That makes them sparse and most people wearing diamonds (even top quality) don't keep them clean enough to be at their best so the chances of the cut differences being obvious is not great, as you say. Does that change my experience or knowledge? No. I'll admit I am a full-blown cut snob. I believe that's what people seeking the best cut quality are trusting me to deliver.

 

[John P]

Serg''s comments again.

Date: 2/19/2009 5:35:22 PM
Author: Serg

Pro: leakage could be positive and give Good contrast, specially for Fire. But I saw good such examples only for fancy cuts

Con: “Dead ring” for RBC is not good even for contrast. Such ring psychologically destroy classical RBC pattern but do not give any compensation in Fire,…

Pro and Con: Diamonds between H&A AGS0 and “Dead ring” are not so bad like you can imagine from Cyclops point of view( IS, FS, ASET).

Date: 2/19/2009 5:50:26 PM
Author: Rockdiamond

As Serg pointed out, what some might see as a ''ring of death'' in an ASET or IS might look quite different viewed real life with two eyes.

But this is applicable more to Near-Tolk stones David. The thread is about 60/60.

 

[Dancing Fire]

Date: 2/19/2009 1:46:57 PM
Author: Rockdiamond

Apparently your friend, along with many other observers, chose a diamond that might be knocked here as badly cut.
Is your friend wrong?
Would telling your friend he got ripped off, and bought a badly cut diamond be a good thing to do?

i didn''t make any comments about his diamonds. i ask him...why buy diamonds in HK when you can buy them cheaper here in the U.S. ?

 

[John P]

Thanks for taking the "profile challenge" David...

Date: 2/19/2009 5:38:51 PM
Author: Rockdiamond

Date: 2/19/2009 4:02:20 PM
Author: John Pollard
David, here are nine profile views of diamonds at or near 60-60. All of them are GIA EX. They range from brilliancy properly returned to the eye that would earn AGS0 to severe enough under-table & girdle leakage to be penalized to AGS6 when ray-traced. Based on these views and the fact that all are GIA EX, which do you suppose you could recommend?

Courage or stupidity....sometimes it''s a fine line John.....heheh
As you''ve mentioned trying to assess a diamond based only in a CG side view is difficult at best....but here goes...

#1 looks to have a thick girdle, and heavy crown. [ AGS0, 60 60 40.8 34.0 stk 6.49mm 1ct ]
#2 also looks thick in the girdle although the crown and pavilion angles look nice. [ AGS1, 60 60 41.2 31.5 stk 6.49mm 1ct ]
#3 seems thin at the girdle [ AGS5, 60 60.2 41.8 33.5 thin 6.54mm 1ct ]
#4- not bad [ AGS4, 60 60.1 41.4 34.5 med 6.53mm 1ct ]
#5 seems to have heavy crown [ AGS4, 60 60.4 41.4 35.0 med 6.53mm 1ct ]
#6 girdle looks a little heavy, but not bad otherwise [ AGS0, 60 60 41.0 33.5 stk 6.49mm 1ct ]
#7- looks about the best of the bunch [ AGS5, 62 60 41.6 33.5 med 6.54mm 1.01ct ]
#8 - seems to have steep crown angles [ AGS6, 62 59.9 41.2 35.0 med 6.54mm 1.02ct]
#9- also not bad, but the girdle seems a bit thin [ AGS5, 59 60.4 41.8 33.5 thin 6.54mm 1ct ]

Details for each in red, above.

David you have a great eye for girdle thickness. All are just thin, med or stk and you nailed the tn and stk every time. You also picked those with the highest crowns which, though logical when zoomed, is pretty cool to me.

It is far harder to predict light return and leakage in profile.
The most brilliant would be #1 #2 and #6. Those with the "ring of death" have reduced brilliance.

ASET images below (I will ask Andrey to post a better-res image...100k limit)
Since these are wire-frames they assume perfect 3D symmetry (impossible IRL) so they are "best case" scenarios.

 

[Rockdiamond]

Well, actually the thead is about two subjects.....60/60, and can GIA EX cut grade be trusted.
I probably shuld have made two threads....
When it comes to 60/60, my point is almost moot. As we''ve seen, most of the stones currently cut to achieve an AGS 0 or GIA EX cut grade are being cut "Near Tolk" vs "Harry Winston standard" - I need to coin a phrase becasue "60/60" is just like the term "Ideal" .
As we''ve seen, simply saying 60/60 does not properly describe what I love in a well cut diamond- the girdle, crown angles and pavillion depth all must be correct, as in any well cut diamond.
I use Winston as an example, as the experience really helped formulate my opinions about diamonds. We looked at literally tens of thousands of stones- and the makes at Winston were absolutely incredible.
The consistency was remarkable. You learned to really distinguish small differences in the make. Painted stones were very easy to spot, for example.
Seeing so many beautiful stones caused me to fall in love with the 60% table
To this day, a 57% table looks small to me. When I see a 55%table, it looks like an OEC practically.....

The cutters I''ve asked about this- none of whom ever heard of PS, so their opinions are not colored by what''s written on the web- they understand that the most discriminating consumers want "Ideal Cut"- or "Hearts and Arrows". They are cutting 55-58% tables because that''s what the most vocal public wants.
Personally, I feel that''s a shame- but remember, no one ever came up with add campaigns for other styles of cutting to go against Lazaare Kaplan- and H&A.
If someone did, this entire conversation might be different.....


In terms of Steep Deep and GIA''s cut grade......there was a series of photos I''ve seen here on PS showing an actual Steep Deep diamond in different views....does anyone know where that is so we can post the photos here?

 

[John P]

Date: 2/19/2009 5:38:51 PM
Author: Rockdiamond

Also a great point about the usage of the word ''ideal''.

The term has been so horribly abused so as to be almost meaningless at this point.
I suppose I use it for lack of a better word- but ''Near Tolk'' sounds reasonable!

Thanks. You actually bring up a good point about 60/60. On first blush I like the Winston reference you have brought - it implies quality - but I am sure there are other cutters of 60/60 with top performance.

 

[Rockdiamond]

Thank YOU John!
I really appreciate the ability to have this conversation.
You have always shown yourself to be open minded, fair and knowledgeable.

BTW- is it just slightly possible that the term "ring of death" might be a teeensy weensy bit.....harsh?

I would never want to understate how valuable the computer models are- but to really see what the ring of .....doom looks like, photos seem a better way to note the differences- if we could get a video, that would be even better....

I might be able to arrange that......hard as it is to find the 60/60 of my dreams, I can probably get my hands on a "steep deep" and take a movie of that.....

 

[JulieN]

I always thought it was Jon who coined "ring of death"

There are some examples floating around on PS. Hideous.

 

[Rockdiamond]

I hate to get all "Those were the days" on you- but Harry Winston in the 1970''s was a truly remarkable place.
Mr Winston had two sons.
Bruce Winston was just about never there.
The other, Ronald Winston, was very interested in the business.
Under his guidance, the company invested huge sums of money into increasing technology associated with diamonds.
They developed a machine to count diamonds. Particularly useful on those JC Penny orders....( 2500 pieces of two point diamonds, 2500 one and a half pointers...etc)
They also put development into a machine to grade a diamond for color- predating the "Colorimeter" by many years.


But the place had some remarkable stones come through.
They had the cutting factory on the fourth floor, right at the main store, on Fifth Avenue and 56th Street.

 

[John P]

Date: 2/19/2009 6:42:14 PM
Author: Rockdiamond

In terms of Steep Deep and GIA''s cut grade......there was a series of photos I''ve seen here on PS showing an actual Steep Deep diamond in different views....does anyone know where that is so we can post the photos here?

It was in this case study David. But that was not a steep/deep of 60/60 make, it was 57T 62.9D (and while not a 60/60 it is GIA EX of dubious quality).

 

[purrfectpear]

I picked #6 as my favorite. Is there a door prize involved?

p.s. admittedly I like smaller tables. I''d be purrrfectly happy in a world with high crowns, small tables, oh...and lower costs

 

[John P]

Date: 2/19/2009 7:09:09 PM
Author: purrfectpear
I picked #6 as my favorite. Is there a door prize involved?

Of course Purr. That virtual diamond is all yours!

I was posting at the time you contributed this and quasi-implied it, but I meant to highlight, as it's critical perspective.

Date: 2/19/2009 5:32:58 PM
Author: purrfectpear
Maybe we just need to define the word 'bad' and 'poor'.

It sort of sounds that bad and poor must be fairly egregiously awful when you use it David (aka 'I don't think there are bad cutters, or I have yet to see even one GIA EX that would be considered poorly cut.')

I think that John and some of the rest of us are saying 'less than optimal' rather than egregiously bad or poor.

I don't think there are bad cutters as much as there are cutters who are willing to sacrifice optimal performance to eek their stones in 'just under the GIA wire' so to speak. They'll sacrifice performance for weight. That doesn't make them bad guys (it sounds like on that we agree?) it makes them smart cookies (but at the possible expense of the best diamond). Ditto for GIA EX grades. They aren't poorly cut to you, but we've seen some that are definitely not as well cut as expected. Maybe we don't agree on the definition of poor? Poor doesn't have to be the worst.

With that reinforced, diamonds I've seen IRL with ASET appearances like that bottom row will be hard sells next to those with more brilliance when compared away from the spotlights.