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

[Rockdiamond]

Unbelievable, but two times in a day Purrfect and I agree!!
Cost is an important factor in all this.
It''s so easy to assume that a GIA VG cut is not as nice looking as an GIA EX cut grade.
But there''s certainly a lot of amazing VG cut grade stones out there.
There are some people that would pick the VG cut grade stone in a blind test. The difference is by no means "night and day" to even a trained observer.
If a person is wanting a big diamond, it might be no sacrifice at all if the buyer went for a VG cut grade. It might be the far better choice for that particular buyer.

I''m not saying that there''s anything wrong with using IS and ASET. If you want that particular look in a diamond, the tools are great.
Although I picked #7 from the profile, for example- and it seems to have a really terrible IS. If you were looking for H&A clearly, that''s not your stone.
I''m saying it''s perfectly OK not to want H&A

 

[Garry H (Cut Nut)]

Date: 2/19/2009 6:41:46 PM
Author: John Pollard
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.

So David you would agree that you did very very poorly on this test.
And consumers should avoid buying round diamonds based on your ability and wierd grading system.
Your best pick rates AGS 5.
Your ''Not Bad''s" were AGS4 and AGS5

Your girdle grading is not at all interesting because I think we all accept that from the grading report.

I rerst my earlier statements that you should not give advice on round brilliant cut diamonds - leave it to the many consumers here

 

[Rockdiamond]

Thank You for participating as well Garry.
If all the diamonds in the example were GIA EX cut grade, then I don't know that I did poorly.
I'm not an AGS kinda guy, although I acknowledge the lab for it's stellar and well deserved reputation. AGS is the "go to" lab for H&A, which is not really my favorite look.
Not that such an exercise says anything about one's ability to select diamonds.
Imagine trying to grade the cut of a diamond from a CG profile, and never get to look into it face up.


I have many times complimented the consumers on PS for their to read IS and ASET- if the buyer is looking for a Near Tolk.
I'm just saying many viewers would choose the "HW" style of cutting if given the choice.

 

[John P]

Date: 2/19/2009 7:27:20 PM
Author: Rockdiamond

I'm not saying that there's anything wrong with using IS and ASET. If you want that particular look in a diamond, the tools are great.
Although I picked #7 from the profile, for example- and it seems to have a really terrible IS. If you were looking for H&A clearly, that's not your stone.
I'm saying it's perfectly OK not to want H&A

But this has nothing to do with H&A David?

The issues (lightness/rings-of-death) show where light is leaking out the bottom of the diamond. That's a reduction in brilliance. They are places where, in Serg's words, the “dead ring” is not good even for contrast as it destroys pattern without giving compensation in fire.

Too much green around the edges also shows the diamond is drawing light from low angles (reflected off walls for example) rather than overhead, where it's most intense. That reduction in intensity can make such stones look smaller than those with edge-to-edge brilliance in soft lighting.

 

[Rockdiamond]

I agree John, but in all fairness, this has nothing to do with my ability to select a diamond.

Or if GIA's EX Cut grade is dependable.
To really do that, we need real diamonds.

 

[Garry H (Cut Nut)]

Date: 2/19/2009 7:27:20 PM
Author: Rockdiamond
Unbelievable, but two times in a day Purrfect and I agree!!
Cost is an important factor in all this.
It''s so easy to assume that a GIA VG cut is not as nice looking as an GIA EX cut grade. You probably are totally unaware of debates and discussion that GIA set their grades rather steep deep so that some nice shallower stones would get good grades from many people. It is well known.
But there''s certainly a lot of amazing VG cut grade stones out there.
There are some people that would pick the VG cut grade stone in a blind test. The difference is by no means ''night and day'' to even a trained observer.
If a person is wanting a big diamond, it might be no sacrifice at all if the buyer went for a VG cut grade. It might be the far better choice for that particular buyer.

I''m not saying that there''s anything wrong with using IS and ASET. If you want that particular look in a diamond, the tools are great.
Although I picked #7 from the profile, for example- and it seems to have a really terrible IS.
RD do you know the difference between Ideal-Scope and ASET?
If you were looking for H&A clearly, that''s not your stone.
I''m saying it''s perfectly OK not to want H&A

And David I do not care what diamonds you select.
(I do worry for the punter who buys from you)

But I do not like you participating in consumer threads when people seek advice because clearly you have no idea about the language, the tools we refer to, the different appearnaces and what is even being discussed.

Your shoot from the hip profile grading is shown up for what it is.
What do you have to offer consumers looking to get advice on buying round diamonds unseen?

 

[Garry H (Cut Nut)]

Date: 2/19/2009 8:01:07 PM
Author: Rockdiamond
I agree John, but in all fairness, this has nothing to do with my ability to select a diamond.

Or if GIA''s EX Cut grade is dependable.
To really do that, we need real diamonds.

For heavens sake - can you read RD?
Have you not understood anything John has said about steep deep GIA Excellents?

 

[Rockdiamond]

I have read a lot of what John has written, and everything he's written here in this thread.
I've looked at lot of GIA EX stones, and never seen what you are talking about.
That's why I asked for photos that we could comment on.
But in all fairness, why don't you give me the parameters to look for, I'll see if I can find, and borrow a diamond that meets the description.
If I can actually see first hand what you're referring to than it would really help.

Maybe for the purposes of this discussion you might want me to photograph and video the diamond ( ducks and runs for cover)

 

[purrfectpear]

This horse is dead.

David is never going to admit that in his opinion any diamond that isn''t frozen spit, windowed to the point you could read a newspaper through it, or totally extinct, is anything but "well cut". He clearly likes diamonds and they''re all cute and sparkly to him. It''s what he sells. He will continue to promote other than AGS0, ACA, or whatever superideal term we use at PS because that''s his stock in trade.

I personally wouldn''t find it so objectionable (after all it''s no different than Jared''s or Robbin''s Bros, or any other average diamond store), but I do think it''s sad that he prices them no less expensive than a consumer could buy a much better cut diamond. He still wants to convince PS consumers that an average diamond is just as good as a better diamond (under the guise of "a different opinion").

I think all we can do is continue to post after his "opinion" that it does not represent a PS respected expert opinion, and that there are excellent tools to help the consumer get the best performing stone for their dollar.

If PS is going to become about sending consumers to buy the average "GIA says it''s EX so it must be best", then I''ll sign up as an expert also and just send them off to the mall.

 

[Rockdiamond]

Purrfect- I agree.
I value being a member here- I don;t want to argue with you - and I really don't want to argue with Garry.
We don't even carry the type of diamonds we're talking about here- so you are correct.

In a discussion about round diamonds, I believe that it's pretty safe to advise people to make sure to have visual observation- in person, or at least good photos- and to go for a GIA EX cut grade. And, of course a return policy.
To me, that is preferable to trying to buy it blind.
I never knocked anyone's diamond- on the other hand I suggested a diamond be considered that others immediately dismissed- a James Allen Diamond.
I sincerely believed that my persepctive added input to add value to the conversation from the shopper's perspective.
If it would satisfy Garry so that we can pleasantly converse , I'd gladly refrain from commenting on any round colorless diamonds

 

[Allison D.]

Date: 2/19/2009 5:32:44 PM
Author: MikeRato1

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

Mike, the goal of the HCA isn''t to tell you that a diamond is crappy or not because it''s not a selection tool. It''s a weeding/rejection tool; its purpose is to help buyers narrow in on those stones which are most likely to be great performers based on a few pieces of parametric data. It''s like a first-round elimination tool.

As with other elimination tools, its goal is to identify stones that are *most/highly* likey to perform well. It may eliminate some nice stones because they are only *somewhat* likely to perform well, but that doesn''t mean those stones aren''t winners.

Your local gal brought up a great point; if you''d never found pricescope, perhaps you would have been satisfied by a stone with a lesser cut grade. But would that last? Maybe....maybe not. PS has many posters who loved their first diamonds but came to realize they visually preferred better cuts once they knew of their existence. Some have even gone so far as to have their stones recut.

You wondered why cutters don''t strive for VG to retain even more weight. I believe it''s because in a good/better/best system, many people want the label "best". Non-Pricescopers still see grading reports in the marketplace, and we''ve all become conditioned to want A+, 5-star, best best best. Weight retention benefits the cutter as long as it doesn''t diminish desirability for the stone; that''s what cutting to the steep/deep end of the EX grade gives them. Once you cross to VG, the benefits of weight retention are negated by potentially diminishing the demand for the stone because it''s not "EX".

 

[strmrdr]

Date: 2/19/2009 9:26:14 PM
Author: purrfectpear

If PS is going to become about sending consumers to buy the average ''GIA says it''s EX so it must be best'', then I''ll sign up as an expert also and just send them off to the mall.

Not going to happen there is a dedicated group of consumers and experts here.

John who deserves ton of credit for having more patients than I do has spent all day working on this thread to see that it don''t.

At least the consumers will get something from John''s hard work and that is a good thing.

 

[purrfectpear]

Date: 2/19/2009 9:36:28 PM
Author: Rockdiamond
Purrfect- I agree.
I value being a member here- I don;t want to argue with you - and I really don''t want to argue with Garry.
We don''t even carry the type of diamonds we''re talking about here- so you are correct.

In a discussion about round diamonds, I believe that it''s pretty safe to advise people to make sure to have visual observation- in person, or at least good photos- and to go for a GIA EX cut grade. And, of course a return policy.
To me, that is preferable to trying to buy it blind.
I never knocked anyone''s diamond- on the other hand I suggested a diamond be considered that others immediately dismissed- a James Allen Diamond.
I sincerely believed that my persepctive added input to add value to the conversation from the shopper''s perspective.
If it would satisfy Garry so that we can pleasantly converse , I''d gladly refrain from commenting on any round colorless diamonds

That''s really just a starting point though. It''s better than totally blind, but photos lie. Look at eBay, look at jewelry TV shows. There are some pretty spiffy looking stones out there in pics, but a slight tilt can hide a bad cut. In fact it can go the other way. We have one PS vendor here who is soooo bad at his pics that I swear he''d never make a sale if that was all he could provide (oops, did I say that

). He has some fabulously fine diamonds but his pics suck.

I''m sorry, but for the online consumer a pic and a video really doesn''t cut it. They could find themselves paying to have diamonds brought in, mailed out, mailed back, etc. all at their own expense.

 

[:)]

Date: 2/19/2009 8:01:07 PM
Author: Rockdiamond
I agree John, but in all fairness, this has nothing to do with my ability to select a diamond.

Or if GIA's EX Cut grade is dependable.
To really do that, we need real diamonds.

Your thread title 'can we trust a GIA Ex cut grade'. Clearly not blindly.

Here is your real diamond. I believe you are familiar with Kelli's 'GIA Ex' that she had to get recut. It does not need clear photos to be able to see the dark ring.
https://www.pricescope.com/community/threads/recut-details-for-rickdiamond.106059/

Here is her recut thread.
https://www.pricescope.com/community/threads/extreme-diamond-makeover-my-wf-recut.96578/

 

[:)]

Date: 2/19/2009 9:00:22 PM
Author: Rockdiamond
I have read a lot of what John has written, and everything he''s written here in this thread.
I''ve looked at lot of GIA EX stones, and never seen what you are talking about.
That''s why I asked for photos that we could comment on.
But in all fairness, why don''t you give me the parameters to look for, I''ll see if I can find, and borrow a diamond that meets the description.
If I can actually see first hand what you''re referring to than it would really help.

Maybe for the purposes of this discussion you might want me to photograph and video the diamond ( ducks and runs for cover)

Kelli''s thread again. Click on link for pics.
https://www.pricescope.com/community/threads/recut-details-for-rickdiamond.106059/

 

[Rockdiamond]

Purrfect- if that''s the case, then we could never buy any of the other shapes online- like Old Mine cuts...I''ve seen a lot of really great photos and video of diamonds and rings that really did convey the idea well.

Clearly, if a person is looking for a Near Tolk type of diamond, tools like IS and ASET work.
I''d never enter into a conversation if was about H&A, ASET or IS. There''s a lot of really great advice given here for these tools and how they relate to the diamond.
Allison''s description of the HCA was excellent.
If that''s what a shopper is looking for - and clearly many are- then that''s the way to go.
I have participated where I have because there''s also people not looking for Near Tolk, or looking for entirely different things in a diamond.
I''m sure Garry could have read those profile views better than I....although I don''t know that anyone could pick out the winners just from looking at profile views.

Since we carry primarily fancy shapes, visual cues are everything. Even though I feel the same way about rounds, if we were going to sell them- especially to the people here- we''d need to use ASET and IS to make sure the stones performed well by those benchmarks.

 

[:)]

Date: 2/19/2009 7:55:17 PM
Author: Rockdiamond
Thank You for participating as well Garry.
If all the diamonds in the example were GIA EX cut grade, then I don''t know that I did poorly.
I''m not an AGS kinda guy, although I acknowledge the lab for it''s stellar and well deserved reputation. AGS is the ''go to'' lab for H&A, which is not really my favorite look.
Not that such an exercise says anything about one''s ability to select diamonds.
Imagine trying to grade the cut of a diamond from a CG profile, and never get to look into it face up.


I have many times complimented the consumers on PS for their to read IS and ASET- if the buyer is looking for a Near Tolk.
I''m just saying many viewers would choose the ''HW'' style of cutting if given the choice.

I just want to make sure that people are aware that h&a refers to optical symmetry and not any certain set of cut numbers. You can have a poorly cut diamond with h&a optical symmetry. You can even have a ''60/60'' with h&a. You can have a well cut diamond without h&a. You need an h&a viewer to properly evaluate this.

 

[Rockdiamond]

Date: 2/19/2009 10:10:04 PM
Author:

Date: 2/19/2009 9:00:22 PM
Author: Rockdiamond
I have read a lot of what John has written, and everything he''s written here in this thread.
I''ve looked at lot of GIA EX stones, and never seen what you are talking about.
That''s why I asked for photos that we could comment on.
But in all fairness, why don''t you give me the parameters to look for, I''ll see if I can find, and borrow a diamond that meets the description.
If I can actually see first hand what you''re referring to than it would really help.

Maybe for the purposes of this discussion you might want me to photograph and video the diamond ( ducks and runs for cover)

Kelli''s thread again. Click on link for pics.
https://www.pricescope.com/community/threads/recut-details-for-rickdiamond.106059/

Kelli''s diamond is now beautiful!
IN relation to this conversation I don''t know that it''s helpful ...all due respect, there''s pleanty of amazing "after" photos, but no "before" photos that are clear enough to see what the diamond looked like before the recut.

 

[Garry H (Cut Nut)]

Date: 2/19/2009 10:17:33 PM
Author:

I just want to make sure that people are aware that h&a refers to optical symmetry and not any certain set of cut numbers. You can have a poorly cut diamond with h&a optical symmetry. You can even have a ''60/60'' with h&a. You can have a well cut diamond without h&a. You need an h&a viewer to properly evaluate this.

i do not think you can have a H&A''s pattern in any 60:60 combination.

David you have seen photo''s of GIA Ex leakage (John posted it, taken on my hand so you can see my fingers thru the center of the stone).
You have also been linked to the article in the journal section here where there is series of articles about the mistakes GIA made, with repsonses from the GIA Cut Team, that you would never know existed because you have no desire to learn, only to keeep your witch doctor voodoo systems intact.

 

[MikeRato1]

Date: 2/19/2009 9:39:06 PM
Author: Allison D.

Date: 2/19/2009 5:32:44 PM
Author: MikeRato1

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

Mike, the goal of the HCA isn't to tell you that a diamond is crappy or not because it's not a selection tool. It's a weeding/rejection tool; its purpose is to help buyers narrow in on those stones which are most likely to be great performers based on a few pieces of parametric data. It's like a first-round elimination tool.

As with other elimination tools, its goal is to identify stones that are *most/highly* likey to perform well. It may eliminate some nice stones because they are only *somewhat* likely to perform well, but that doesn't mean those stones aren't winners.

Your local gal brought up a great point; if you'd never found pricescope, perhaps you would have been satisfied by a stone with a lesser cut grade. But would that last? Maybe....maybe not. PS has many posters who loved their first diamonds but came to realize they visually preferred better cuts once they knew of their existence. Some have even gone so far as to have their stones recut.

You wondered why cutters don't strive for VG to retain even more weight. I believe it's because in a good/better/best system, many people want the label 'best'. Non-Pricescopers still see grading reports in the marketplace, and we've all become conditioned to want A+, 5-star, best best best. Weight retention benefits the cutter as long as it doesn't diminish desirability for the stone; that's what cutting to the steep/deep end of the EX grade gives them. Once you cross to VG, the benefits of weight retention are negated by potentially diminishing the demand for the stone because it's not 'EX'.

thanks allison, i know that but my fiance did not even know what hca was, let alone what clarity meant, she just wanted the one that looked best to her.
as far as why cutters dont strive for a VG... the conservation we had is if i walked in to the store uneducated (not even saying that i am that knowledgable) i would have seen the gia/ags report and looked right past it and took the stone in my hand (speaking from experience of what my girl did)

edit: as far as the rest of this topic goes i am opting out as for reasons that are wayyyy over my head lol

 

[Dancing Fire]

Date: 2/19/2009 9:39:06 PM
Author: Allison D.

Your local gal brought up a great point; if you''d never found pricescope, perhaps you would have been satisfied by a stone with a lesser cut grade. But would that last? Maybe....maybe not. PS has many posters who loved their first diamonds but came to realize they visually preferred better cuts once they knew of their existence. Some have even gone so far as to have their stones recut.

You wondered why cutters don''t strive for VG to retain even more weight. I believe it''s because in a good/better/best system, many people want the label ''best''. Non-Pricescopers still see grading reports in the marketplace, and we''ve all become conditioned to want A+, 5-star, best best best. Weight retention benefits the cutter as long as it doesn''t diminish desirability for the stone; that''s what cutting to the steep/deep end of the EX grade gives them. Once you cross to VG, the benefits of weight retention are negated by potentially diminishing the demand for the stone because it''s not ''EX''.

i hate to admit it

but i do agree with Alj.

 

[arjunajane]

Date: 2/19/2009 8:15:32 PM
Author: Garry H (Cut Nut)

And David I do not care what diamonds you select.
(I do worry for the punter who buys from you)

But I do not like you participating in consumer threads when people seek advice because clearly you have no idea about the language, the tools we refer to, the different appearnaces and what is even being discussed.

Your shoot from the hip profile grading is shown up for what it is.
What do you have to offer consumers looking to get advice on buying round diamonds unseen?

Big Fat Ditto. Not impressed at seeing that.

 

[John P]

Date: 2/19/2009 5:32:44 PM
Author: MikeRato1

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

Understood. In our “best” seeking society I understand why you saw VG as a condemnation. I know Garry has plans to somehow indicate more info is needed in such cases in the future - without compromising the simplicity of the tool I hope.

Do we have an iPhone HCA app yet?

Very forward-thinking of you to bring the mrs2b btw.

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

They’re out there Mike, just not with GIA reports. Allison's right about "best" but not all consumers know there are different levels of best... Remember that the path a diamond takes to lab and market is chosen by extremely smart people who know all the different systems and outlets. If the rough will yield a “magic weight” at XYZ proportions outside of EX, there are other options to consider. When I last checked, EGL’s Premium cut grade spanned about all of GIA's EX, VG and even some G combinations. So while XYZ would never earn EX it might be "best" on paper from another lab. Some labs offer reports with no cut grade at all, and don’t forget the millions of loose diamonds sold without grading reports. Ungraded diamonds are also bought and used by jewelry manufacturers in finished pieces.

Planners upstream have plenty of options (and we haven't even touched on choices due to differing color/clarity standards). GIA reports trade at high values in nearly all markets, so will be the first choice in many cases, but not the path for all.

 

[Ellen]

Date: 2/19/2009 5:55:49 PM
Author: John Pollard
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.

I can''t believe you said that in here John. Home of OCD? Why, I literally cleaned the first round of Rhodium right off my ring.

However, your point may be quite relevant out there ------->

Funny, most people who''ve seen my (extremely well cut) round, the most common/seen shape of all, know it''s different (in a good way), they just don''t know why. It''s the cut of course. Cut really does make a difference.

*exiting*

 

[stone-cold11]

Date: 2/19/2009 9:00:22 PM
Author: Rockdiamond

That''s why I asked for photos that we could comment on.

But in all fairness, why don''t you give me the parameters to look for, I''ll see if I can find, and borrow a diamond that meets the description.

If I can actually see first hand what you''re referring to than it would really help.

Maybe for the purposes of this discussion you might want me to photograph and video the diamond ( ducks and runs for cover.

From what I see, the parameters are there for you to take. Just take Kelli''s example. Or if you want to explore the 60/60, just used the HCA plot for the table 60%, find a GIA Ex cut whose crown and pav angle that lands in the HCA blue zone and score above 4, that should do it.

 

[John P]

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

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.

I'd argue that David: Rapaport article.

Here's my own input. The names Okuda, Shigetomi, Gilbertson, Holloway and Sasian are linked to the evolution of natural reflectors. Sivovolenko, Shelementiev, Quick and Yantzer to their incorporation in ray-tracing. These are names connected with upstream cutting solutions, major universities and gemological laboratories, not sales tools or gimmickry.

No other approach is peer-reviewed and published by the society of optical engineers; not human observation, not proportions ranges, not pixel counting. Experts at the major labs, some of the most qualified appraisers and many pros have exhaustive practical experience with IS and ASET. DiamCalc is a design tool which does far more than simulate IS and ASET views (its use in this thread) but it simulates them with incredible accuracy. Just as darkfield helps us understand clarity, comparing live diamonds to their reflector views and DC models boosts perception and understanding of visual qualities.

I train the jewelers dealing our brand. They're astonished at what they learn using reflectors, and how it enhances communication with clients. I say this with great respect to experienced tradesmen, in no way am I ‘talking down.’ On the contrary, I find veterans often adapting fastest with more insight about “why” they see what they see. Familiarity with these tools has confirmed why Garry's HCA thresholds exist and, more importantly, has taught me where most people will see reductions in brilliance away from sales spotlights.

Lately I’ve been working to determine avg proportions from loupe and ASET views. It’s like estimating pavilion depth using table reflection as cutters and graders do...and while ASET gives more info asymmetry and variations are a challenge. It's fun if nothing else. I will be quick to add that fancy shapes and fancy colors in reflectors are different creatures and don’t follow the simpler rules of brilliants - though with experience and experimentation judgments can be made. I presume you haven’t spent time correlating live diamonds with modern reflectors and ray-tracing technology, but I think you'd find it a pleasant exercise David.

Date: 2/19/2009 9:00:22 PM
Author: Rockdiamond
I have read a lot of what John has written, and everything he's written here in this thread.
I've looked at lot of GIA EX stones, and never seen what you are talking about.
That's why I asked for photos that we could comment on.
But in all fairness, why don't you give me the parameters to look for, I'll see if I can find, and borrow a diamond that meets the description.
If I can actually see first hand what you're referring to than it would really help.

Maybe for the purposes of this discussion you might want me to photograph and video the diamond ( ducks and runs for cover)

That might be positive and instructive for everyone. If you look at the top post on this page I listed the main proportions of each GIA EX simulation next to your observations (all stars 50%, lower halves 82% which will read 80% on the report). Perhaps you can locate one of those combinations predicted as AGS5 or AGS6 or close to it (PA within 0.2 and CA within 0.5) in 3-8 grains. It will be important to also have one predicted as AGS0, spot-on.

Photograph them separately so the camera is centered over each at the same distance. In nominally diffused lighting (lab fluoros) use white, gray and black backgrounds, then sitting on the skin between two fingers - GH inspiration. We need IS and ASET photos but this is hard without a formal setup. I have the portable versions but they’re darn tricky for photos. Perhaps we split shipping to get good reflector photos and 3D scans?

 

[John P]

Date: 2/19/2009 7:27:20 PM
Author: Rockdiamond

...It's so easy to assume that a GIA VG cut is not as nice looking as an GIA EX cut grade.
But there's certainly a lot of amazing VG cut grade stones out there.
There are some people that would pick the VG cut grade stone in a blind test. The difference is by no means 'night and day' to even a trained observer...

[Meant to reply to this earlier]

No doubt. I believe it has to do with the amount of obstruction GIA used. It’s unrealistic and, unfortunately, allowed some steep-deeps in while banishing combos in the 40.4-40.5 PA range to VG. That’s a whole ‘nother subject - and hopefully a revision in GIA’s future.

 

[John P]

Date: 2/19/2009 9:42:10 PM
Author: strmrdr

Date: 2/19/2009 9:26:14 PM
Author: purrfectpear

If PS is going to become about sending consumers to buy the average ''GIA says it''s EX so it must be best'', then I''ll sign up as an expert also and just send them off to the mall.

Not going to happen there is a dedicated group of consumers and experts here.
John who deserves ton of credit for having more patients than I do has spent all day working on this thread to see that it don''t.
At least the consumers will get something from John''s hard work and that is a good thing.

You post as if I have a life?

Thanks Karl. In hindsight I wish I''d been gathering specimen photos but it’s extremely hard in the handhelds. Some places (not in our network) also get nervous when a camera comes out.

 

[John P]

Date: 2/20/2009 12:40:07 PM
Author: Ellen

I can''t believe you said that in here John. Home of OCD? Why, I literally cleaned the first round of Rhodium right off my ring.

I know. I think those words are in the PS National Anthem?

 

[Lorelei]

Date: 2/20/2009 1:17:17 PM
Author: John Pollard

Date: 2/20/2009 12:40:07 PM
Author: Ellen

I can''t believe you said that in here John. Home of OCD? Why, I literally cleaned the first round of Rhodium right off my ring.

I know. I think those words are in the PS National Anthem?

LOL!!