Show me examples of good numbers, poor idealscope

[pfunk]

In light of the recent discussions on predictive light performance based off of the numbers, I wanted to pose this question. I am curious if someone could provide me images of diamonds that seem to have great numbers on paper, but have poor idealscope images that would translate to visual defects in real life? As a beginner I am likely over simplifying things, but it seems to me that if you buy a RB diamond cut to ideal numbers with angles that complement each other, it should almost certainly translate to a favorable idealscope image. I would define ideal numbers to me to include

Depth <62
Table 53-58
Crown angle 34-35
Pavilion angle 40.6-41
Girdle range thin to sl thick
Lgf 75-80%

To further clarify, I would only consider diamonds where the angles are complementary. For example, if the crown angle is on the high side at 35 degrees, I would only consider pavilion angles on the lower side (40.6-40.. If crown is shallow at 34, consider pavilions from 40.8 to 41. Also assume excellent polish and symmetry and no negative effects from something other than the cut (i.e. Clarity issues).

What I am trying to figure out is how likely is it to get a poor IS image from a diamond that seems good on paper? Is it common to see ugly ideal scope images on diamonds with good, complementary angles? I often see people mention how they would not purchase a diamond without an ideal scope, but then wonder how anyone ever finds beautiful ideal diamonds in a brick and mortar store where ideal scopes are nearly non existent? How much variation can there be between these ideal cut diamonds that an ideal scope would uncover?

 

[BrownyJones]

Awesome scenario.

 

[Niel]

I guess I'm confused. No one is saying you can't pick a round specifically by the numbers.... In fact, I do believe people on here say its the only shape that you can.

People who like to get idealscopes like to nit pick to get the best cut. If you don't care about nit picking, by all means, I agree, go with a drop shipped or someone that doesn't provide more information.

 

[chrono]

Granted these are only using the HCA...

[URL='https://www.pricescope.com/community/threads/round-cut-with-good-hca-but-bad-idealscope-aset-image.161161/']https://www.pricescope.com/community/threads/round-cut-with-good-hca-but-bad-idealscope-aset-image.161161/[/URL]
[URL='https://www.pricescope.com/community/threads/have-you-ever-seen-a-diamond-with-good-hca-and-bad-idealscope.127492/']https://www.pricescope.com/community/threads/have-you-ever-seen-a-diamond-with-good-hca-and-bad-idealscope.127492/[/URL]

 

[pfunk]

I guess I'm confused. No one is saying you can't pick a round specifically by the numbers.... In fact, I do believe people on here say its the only shape that you can.

People who like to get idealscopes like to nit pick to get the best cut. If you don't care about nit picking, by all means, I agree, go with a drop shipped or someone that doesn't provide more information.

You are correct in that sometimes people will say the numbers give you a good start, but there are others who say they would never buy any diamond without an idealscope image. I see it often where people post diamonds with great numbers and then get the response "looks good, now get an idealscope image." Or "you never know without an idealscope what kind of performer it is". Then you have people who pick three diamonds with great numbers and all the idealscope images look great. In fact, often they are nearly identical. People seem to imply to consumers that it's still possible to get a dud that has great numbers, and that IS is the way to prevent that. I was hoping to see examples that proves that.

 

[pfunk]

Granted these are only using the HCA...

[URL='https://www.pricescope.com/community/threads/round-cut-with-good-hca-but-bad-idealscope-aset-image.161161/']https://www.pricescope.com/community/threads/round-cut-with-good-hca-but-bad-idealscope-aset-image.161161/[/URL]
[URL='https://www.pricescope.com/community/threads/have-you-ever-seen-a-diamond-with-good-hca-and-bad-idealscope.127492/']https://www.pricescope.com/community/threads/have-you-ever-seen-a-diamond-with-good-hca-and-bad-idealscope.127492/[/URL]

Thanks so much for this reply chrono. One of these links brought me to a pretty good example here: https://www.pricescope.com/community/threads/diamond-should-i-bite.144057/

This diamond certainly looks like it shows a little leakage or obstruction on the images. The GIA numbers would have passed for me, but the Sarin scan revealed more. The crown angle average was actually a little over 35 and the pavilion was 40.9 but rounded to 40.8 on GIA. Those angles don't complement real well and are, I assume, the reason for the defects on the reflector images. I wonder how common this is. Thanks for posting!

 

[Paul-Antwerp]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

 

[pfunk]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

 

[Texas Leaguer]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

pfunk,
Not answering for Paul, but having a hearts and arrows image will inform you about the 3D symmetry that is so important to fill in the information gaps resulting from rounded and averaged data points. Ideal scope is also helpful in this regard as well.

In regards to your initial premise of whether analytics over and above the numbers on a report translate to meaningful real life differences, I believe they do. Precision alignment in 3dimensions allows for all the facets to do their job correctly as per the facet design. Diamonds can have good numbers on a GIA report but if not correctly aligned can significantly alter the virtual facet patterns and sizes. It therefore alters scintillation and fire in unintended ways.

 

[Paul-Antwerp]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

Your last sentence is probably the most important. It is extremely dependent upon the definition of poor or good.

For me personally, whatever GIA-EX I see, regardless of supposed H&A or nice Idealscope, I see unnecessary weight-retention ranging from 1% to 15% and under-achievement in beauty. But that is personal.
I see consumers appreciating the differences in beauty, and considering the money well-spent and actually a money-saver.
I see other consumers clearly observing the differences in beauty, but not willing to give up an illusive carat weight (or color or clarity), thus having a completely different definition of 'good enough'.
I see many consumers simply dismissing the differences in beauty, in fact not wanting to try and see it. They have a definition they prefer not to challenge, and that is their prerogative.

But realizing that your questions hinge on the definition of poor or good, me having an extremely strict definition of good does not make me the correct person to answer your follow-up-questions. I still have not seen a diamond from elsewhere, that I did not consider improvable. From that perspective, I cannot answer your questions.

Live long,

 

[luvdajules]

Hi OP, this is such a great educational thread (if one reads all the links). Many people understand this, but worth repeating...new posters are asking great questions and seeking guidance for special occasions, once in a lifetime type purchases, so people giving advice want to be extra respectful and conservative in their choices, unless a posters seeks advice on a non-typical make/specs of diamond. So, that's why I've looked at GIA reports, then suggest to get IS or ASET if they can get one. If they can't, at least they can work with an appraiser who can (during the inspection period). Good luck in your search!

 

[pfunk]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

pfunk,
Not answering for Paul, but having a hearts and arrows image will inform you about the 3D symmetry that is so important to fill in the information gaps resulting from rounded and averaged data points. Ideal scope is also helpful in this regard as well.

In regards to your initial premise of whether analytics over and above the numbers on a report translate to meaningful real life differences, I believe they do. Precision alignment in 3dimensions allows for all the facets to do their job correctly as per the facet design. Diamonds can have good numbers on a GIA report but if not correctly aligned can significantly alter the virtual facet patterns and sizes. It therefore alters scintillation and fire in unintended ways.

TL, thanks for your input. It is very helpful as I admittedly have some difficulty distinguishing the difference between the "optical" symmetry that a hearts image reveals vs the symmetry indicated on a GIA report. What I was trying to figure out was whether a good hearts image is evidence enough that the angles have little deviation, or if that can only be gathered from an actual scan of the diamond. Also, if the diamond has complementary angles and 3d precision as evidenced by hearts and arrows, is it still possible to get a diamond with defects that are made obvious when looking through the idealscope?

I know the idealscope is a very useful instrument that is super easy for consumers to understand and therefore has tremendous value. But so many diamonds are available that do not have idealscope images and it seems they get eliminated a lot of the time because of the push here to make sure to get an idealscope image. Even considering the wide range of possible diamonds when accounting for GIA rounding, I feel like the stones in the range I have outlined above are still cut very well and can't see how there would be very many that look ugly through an idealscope. I was hoping to see some exaples though, where the hideousness of GIA rounding was revealed.

 

[Texas Leaguer]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

pfunk,
Not answering for Paul, but having a hearts and arrows image will inform you about the 3D symmetry that is so important to fill in the information gaps resulting from rounded and averaged data points. Ideal scope is also helpful in this regard as well.

In regards to your initial premise of whether analytics over and above the numbers on a report translate to meaningful real life differences, I believe they do. Precision alignment in 3dimensions allows for all the facets to do their job correctly as per the facet design. Diamonds can have good numbers on a GIA report but if not correctly aligned can significantly alter the virtual facet patterns and sizes. It therefore alters scintillation and fire in unintended ways.

TL, thanks for your input. It is very helpful as I admittedly have some difficulty distinguishing the difference between the "optical" symmetry that a hearts image reveals vs the symmetry indicated on a GIA report. What I was trying to figure out was whether a good hearts image is evidence enough that the angles have little deviation, or if that can only be gathered from an actual scan of the diamond. Also, if the diamond has complementary angles and 3d precision as evidenced by hearts and arrows, is it still possible to get a diamond with defects that are made obvious when looking through the idealscope?

I know the idealscope is a very useful instrument that is super easy for consumers to understand and therefore has tremendous value. But so many diamonds are available that do not have idealscope images and it seems they get eliminated a lot of the time because of the push here to make sure to get an idealscope image. Even considering the wide range of possible diamonds when accounting for GIA rounding, I feel like the stones in the range I have outlined above are still cut very well and can't see how there would be very many that look ugly through an idealscope. I was hoping to see some exaples though, where the hideousness of GIA rounding was revealed.

Here's my take on your question in bold. It's best to have all the analytics you can but if you have good numbers on the report and good hearts and arrows images you can be pretty comfortable that an ideal scope would not show defects that would be problematic in real life. Hearts and arrows is essentially a snapshot of faceting precision. That said, you can have great precision in a stone that has proportions that are non-optimal. But if you are looking in that sweet spot range of parameters you can avoid that problem to a large extent.

 

[Niel]

Seems again it comes down to your definition of poor. You're using the terms "hideousness" and"ugly".

I dont think anyone is saying these stones would be either of those things. I think its a matter of them not meeting the standards of some of the people on this site.

 

[pfunk]

Seems again it comes down to your definition of poor. You're using the terms "hideousness" and"ugly".

I dont think anyone is saying these stones would be either of those things. I think its a matter of them not meeting the standards of some of the people on this site.

I agree Niel. I should better define what I think "poor" means around here. It seems to me that any idealscope image that shows a little bit of leakage, even if very minimal, is often dismissed as a poor performer. Which as you mentioned is likely due to the high standards of the prosumers and regulars here. As a consumer who read a ridiculous amount of material from PS during my search, I just get the impression that a lot of consumers here are pushed towards only the very best diamonds with perfect aset and idealscope images. I am sure that is a product of both high standards for prosumers as well as a precaution to ensure the consumer isnt taking a risk on a diamond that might not be beautiful to them. But as long as I have been here (the past few months) I can't recall diamonds cut to ideal numbers as outlined above that came back with idealscopes showing leakage that would be easily perceived and detrimental to beauty. I have, however, heard MANY times that you just cant trust GIA report numbers if you want to know you're getting a beautiful diamond because of the rounding of numbers.

 

[luvdajules]

very astute observations...also, it takes awhile of reading and learning to to scratch the surface of diamond knowledge. However, mostly I think people should at least know what they are buying (and how it will perform visually) and get a fair price for it, whether its a super ideal or another make.

 

[Texas Leaguer]

In some ways, I think what you see here is a natural progression. The more you learn about the importance of cut quality, the less you want to compromise it. Whereas, when you learn about the other C's you come to understand that some compromises can easily be made without sacrificing much at all in terms of beauty.

Where obsessing on cut quality gets irrational is when other things are being compromised too much. For instance, it makes no sense to me to hold out for a superideal while being willing to push into clarity areas that may cause the stone to under-perform. Or requiring proof of immaculate cut precision of a strong fluorescent stone while taking it on faith that the stone has zero transparency issues.

It's great to spend alot of time researching a diamond purchase. But in the end the goal is to make a decision that optimizes all the C's in a way that truly makes sense.

 

[Karl_K]

An IS image to me is to check on what the number information is telling you with rounds.
I am not a fan of buying a diamond without a lot of information and checking what each set of information in different ways.
For rounds:
The hca is a check on gia EX/AGS0
Then an IS image is a check on that. Shows leakage, rough check for painting digging and optical symmetry.
Then a heart image is a check on that. Shows optical symmetry more clearly.

 

[KobiD]

Hey Pfunk. I find it interesting that we both kicked off our journey around the same time, and alot of our queries and thoughts are inline with eachother.

From what I have seen if you stick with complementary numbers as you have suggested, and optical symmetry then I would say its very likely that the imaging would simply confirm what you expect. I'll use WF as an example as they have a large listing complete with all the imaging. By searching through the Expert Selection you can begin to gauge things that effect the overall performance. From what I have seen, its most noticably that as you approach the 35/40.9 CA/PA you get varying degrees of leakage under the table although there are still a few diamonds that fall into this category with more middle of the road angles. They sometimes show some minor imperfections in the IS/ASET but generally not leakage.

For example compare the following

35/40.9 - Some leakage. Would be slammed by most here, but I'm sure still looks quite beautiful in reality. http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3171986.htm

35/40.9 - Just not as vibrant under the table as most would expect. Would be told you could do better. Again, I'm sure it would be a beautiful stone. http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2998702.htm

34.5/40.8 - The IS appears quite alright. A nice consistant red throughout, however on inspection the ASET shows some areas toward the outer with less brightness (indicated by the green). Would anyone notice this with the naked eye? http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3222852.htm

So, I get where you are coming from. There is a very big push to spend the very most you can on CUT, but at the same time most people will suggest an eye clean SI1. At the end of the day, if the two different areas you are compromising on aren't entirely visible unless inspected through a tool, or under heavy magnification then they could be considered similar. I think both probably play more into the mind clean aspect than anything else. It all depends what the particular buyer is looking for within their budget. There is no denying that a precision cut, within the middle of TIC parameters, and perfect optical symmetry is a beautiful work of art, but thats not to say that some slight leakage is going to make a less perfect stone BAD/horrible.

 

[pfunk]

Hey Pfunk. I find it interesting that we both kicked off our journey around the same time, and alot of our queries and thoughts are inline with eachother.

From what I have seen if you stick with complementary numbers as you have suggested, and optical symmetry then I would say its very likely that the imaging would simply confirm what you expect. I'll use WF as an example as they have a large listing complete with all the imaging. By searching through the Expert Selection you can begin to gauge things that effect the overall performance. From what I have seen, its most noticably that as you approach the 35/40.9 CA/PA you get varying degrees of leakage under the table although there are still a few diamonds that fall into this category with more middle of the road angles. They sometimes show some minor imperfections in the IS/ASET but generally not leakage.

For example compare the following

35/40.9 - Some leakage. Would be slammed by most here, but I'm sure still looks quite beautiful in reality. http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3171986.htm

35/40.9 - Just not as vibrant under the table as most would expect. Would be told you could do better. Again, I'm sure it would be a beautiful stone. http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2998702.htm

34.5/40.8 - The IS appears quite alright. A nice consistant red throughout, however on inspection the ASET shows some areas toward the outer with less brightness (indicated by the green). Would anyone notice this with the naked eye? http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3222852.htm

So, I get where you are coming from. There is a very big push to spend the very most you can on CUT, but at the same time most people will suggest an eye clean SI1. At the end of the day, if the two different areas you are compromising on aren't entirely visible unless inspected through a tool, or under heavy magnification then they could be considered similar. I think both probably play more into the mind clean aspect than anything else. It all depends what the particular buyer is looking for within their budget. There is no denying that a precision cut, within the middle of TIC parameters, and perfect optical symmetry is a beautiful work of art, but thats not to say that some slight leakage is going to make a less perfect stone BAD/horrible.

Kobi, I agree. We seem to be on the same page with the questions we have posed since coming here. Those diamonds are really good examples of where you can start to see leakage creep in despite good numbers. As usual, it seems to show up when those pavilion angles approach 41 with crown angles that are also on the high side of ideal. Thanks for sharing.

As you mention, the emphasis around here is always on cut, as it should be with it being the driver of performance and beauty. Having said that, I think there is a point where the returns diminish and most average consumers won't see a visual difference in casually examining the diamond. Are there visible differences? Sure there must be, but is it worth the added cost? That depends on personal preference and where you want to spend your money. I just get the feeling people are often pushed towards spending the extra money on precision cuts, even if it means sacrificing size, something that is easy for most everyone to see. I am fortunate enough that I was able to purchase both an AGS 000 and a GIA xxx and compare them side by side over several days. The only difference that was easily perceivable was the size. If I had posted the second stone for consideration, I am sure I would have been told that I should pass on it without an idealscope or I'd be risking it. I feel like if you stick to the numbers I outlined at the start of this thread, you are likely to end up with a beautiful, strong performer. However, I see people talked out of such stones if they don't have or cant get an idealscope image. In reality, it seems like poor performance would be an exception, though it is communicated to be more of the rule at times.

 

[KobiD]

I think it largely depends on what you consider to be acceptable, and without having the opportunity to make real life comparisons between stones, the safest method is to acquire as much data as possible and make an educated decision. If you have middle of the range figures it appears to be a safe bet. If you have angles leaning towards the edges most suggest an IS/ASET as confirmation.

Personally, I'd have no issues having some leakage at levels shown in the images above (especially if getting them for a little less coin). Not everyone would. I would like to see some examples of how both clarity and optical symmetry issues can impact on the performance of a stone, even when angles are in the right area.

Another thing while on the topic, at what size do these factors become more important? In a small diamond the contrast, facetting, clarity, and colour all are probably less visible to the eye. As everything increases so does so does the influence of all the factors, as well as the price.. exponentially. This is also something that rarely seems to be mentioned, or given weight in the decision.

 

[Texas Leaguer]

Kobi/pfunk,
You are both level-headed independent thinkers and I cannot disagree with your logic. You have done alot of good research and you are comfortable with making slight compromises in cut precision by virtue of the fact that the diamonds will still be beautiful and that the deficits may not be readily apparent in real life. The position that I see you both gravitating towards is that stepping up from ideal to super-ideal delivers a diminished return on the extra investment that might be better spend on another C. Every diamond buyer has to weigh many factors and plenty of people do come to this conclusion.

But I disagree with the sentiment that it is somehow wrong for consumers to be encouraged to seek elite cut quality. In some circles the pendulum may have swung back past nuetral, but one of the historical problems with the diamond market is that there have been too many voices for compromise in cut quality. That has led to a situation where for over a hundred years the market has been overstuffed with mediocre cuts, depriving consumers from enjoying the full magnificence of the diamonds they have purchased.

The information age has only recently begun to change the dynamic. But those new voices that we are starting to hear are changing the way manufacturers approach their craft and the result is increasing availability of finer crafstmanship and more beautiful diamonds for everyone to choose from. I think those voices should be encouraged.

While it might sound a bit self-serving to some, I truly believe it's better for the entire market if those in a position to educate and guide consumers err on the side of top precision and light performance.

 

[KobiD]

Thanks TL.

I believe I may have taken it off topic a bit with my posts, leading towards the compromising and encouragement, although in all honesty I think you are more so picking up on my opinion from several of my posts. I don't disagree with your opinion either.

If you consider that clarity and colour are natural attributes of a particular diamond, and size (to an extent, from the rough of course) and cut are largely dependent on the human element of cutting, it makes sense to strive to cut to precision. From my own experiences in hands on crafting (engine work of all things) I also appreciate how much additional time and effort goes into precision, and also how even when striving to achieve tight tolerances that it is not hard for a simple mistake to push things .1mm out of spec. I I would speculate that most of the diamonds you have in the Expert Selection are either due to such things, or influenced by attributes/characteristics you cannot control.

This is where I think pfunk was leading with his post. Of those diamonds who have a symmetrical cut, with good middle of the range TIC proportions, how likely is it that a clarity issue will cause a concernable issue with performance (as viewed with ASET/IS)?, with my definition of conernable being more than just a few lighter sections on an ASET image.

Without a doubt as you start to move towards the edges of the TIC range there is no doubt that you begin to compromise, and compromise is and always will be a personal decision.

 

[pfunk]

Kobi/pfunk,
You are both level-headed independent thinkers and I cannot disagree with your logic. You have done alot of good research and you are comfortable with making slight compromises in cut precision by virtue of the fact that the diamonds will still be beautiful and that the deficits may not be readily apparent in real life. The position that I see you both gravitating towards is that stepping up from ideal to super-ideal delivers a diminished return on the extra investment that might be better spend on another C. Every diamond buyer has to weigh many factors and plenty of people do come to this conclusion.

But I disagree with the sentiment that it is somehow wrong for consumers to be encouraged to seek elite cut quality. In some circles the pendulum may have swung back past nuetral, but one of the historical problems with the diamond market is that there have been too many voices for compromise in cut quality. That has led to a situation where for over a hundred years the market has been overstuffed with mediocre cuts, depriving consumers from enjoying the full magnificence of the diamonds they have purchased.

The information age has only recently begun to change the dynamic. But those new voices that we are starting to hear are changing the way manufacturers approach their craft and the result is increasing availability of finer crafstmanship and more beautiful diamonds for everyone to choose from. I think those voices should be encouraged.

While it might sound a bit self-serving to some, I truly believe it's better for the entire market if those in a position to educate and guide consumers err on the side of top precision and light performance.

TL, thanks for keeping a presence in this thread. I always find your responses to be very well thought out and genuine. I realize this has taken somewhat of a turn to a discussion of ideal vs super ideal but that was not my intent. I do not mean to diminish the added benefit of stepping up to a super ideal cut diamond or to say that it is not worth it to certain consumers. Without a doubt it is, and I have seen many consumers asking for that level of precision. Also, we as consumers are very lucky to have people like yourself demanding that cut quality be an expectation and not a luxury. There are so many beautiful diamonds available because of the push that you and others have made to bring cut quality to consumers. Thank you for that.

What I question is how often consumers are swayed from diamonds that have great numbers and pushed towards only the diamonds with a wealth of information (ideal scope, aset, hearts images). Rarely can you find diamonds with all of this info unless you are looking at the super ideal cuts. That information is great to have and so reassuring for consumers, but it doesn't mean the next diamond that is cut to ideal proportions but lacking an idealscope image is any less beautiful. While performance is likely to diminish at the edges of the ideal range, especially when being measured by sophisticated computers, it doesn't mean that the diamond isn't going to be beautiful to people. I would argue the great majority of consumers here would still find such a diamond (edge of ideal with some leakage) beautiful. Instead, they seem to be told that they stand to give up a great deal in performance by straying from perfection. Enough so to be readily apparent to the average consumers eye. That is what I question.

 

[Rhino]

I've shot all this in video. GIA X diamond with 34.5/40.8 and AGS 2 in light performance with sub par optics. Not sure if I have the graphics saved as I shot this a while back but in answer to your question YES ... I would never lay out my capital on just the average numbers alone even if they appear to be the best on paper.

 

[Rhino]

An IS image to me is to check on what the number information is telling you with rounds.
I am not a fan of buying a diamond without a lot of information and checking what each set of information in different ways.
For rounds:
The hca is a check on gia EX/AGS0
Then an IS image is a check on that. Shows leakage, rough check for painting digging and optical symmetry.
Then a heart image is a check on that. Shows optical symmetry more clearly.

An IdealScope image for painting and digging Karl?

 

[Rhino]

I think that you should consider the issue with some more info. What is the value of these numbers? Considering that GIA is generally the most used lab, this is the situation regarding GIA-reports:

1. The number on the report is the average of 8 individual measurements. There is no info on the report to what extent the individual measurements are close to or far off that average. Now, one may possibly agree that light performance is predictive, but if 2 equal numbers can mean 2 totally different realities, one cannot truly consider these numbers predictive, no?

2. Furthermore, the number on the report is rounded. 40.6 in PA may mean anything from an average of 40.51 to 40.69. A 34.5 in CA may mean anything from 34.26 to 34.74 average. Again, with so many potentially different realities behind one number, how can one consider such number to be predictive of light performance?

3. The report says nothing about the actual position of the facets, whose average angles are measured. What a diamond does with light not only depends on the individual angles of the facets, but also on the exact position of the facets. That info is unknown.

For those simple technical reasons only, it is already theoretically impossible to deduct a predictive light-performance score from these numbers only, let alone have practical results. As so often, the GIA-report is a rejection-tool, not a selection-tool.

Live long,

Paul, thanks for the detailed response. I do understand that GIA rounds the numbers, and that there is no way of knowing the deviation from the average angle measurement without more info, such as a sarin scan. Let me ask you this then: is a good pattern of hearts and arrows indicative that the deviation from the average is small? Or does the pattern of hearts and arrows tell you nothing about the deviation from average?

Even with the rounding on GIA reports, it seems like you must be able to somewhat predict good performance if you stick to a small range of angles and make sure they are complementary. That is, if you ensure that there is excellent symmetry throughout the diamond. It seems unlikely that you would end up with a diamond with poor performance on an ideal scope, but i'd love to be proven wrong. Though i suppose that is very dependent on what the definition of poor is.

Paul's answer nails it. In response to your comments pfunk yes ... optical symmetry can save a diamonds optics and improve it's light performance. I authored an article a while back and used examples of diamonds that scored over 2 on the HCA yet were perfectly fine because of precise Optical Symmetry (ala H&A diamonds). While there are diamonds on the market that aren't H&A's and look great I can point to many examples where H&A optical symmetry is what made the difference between a top tier diamond (optically) and sub par. Good questions, good thread.

Kind regards,
Rhino

 

[Karl_K]

An IS image to me is to check on what the number information is telling you with rounds.
I am not a fan of buying a diamond without a lot of information and checking what each set of information in different ways.
For rounds:
The hca is a check on gia EX/AGS0
Then an IS image is a check on that. Shows leakage, rough check for painting digging and optical symmetry.
Then a heart image is a check on that. Shows optical symmetry more clearly.

An IdealScope image for painting and digging Karl?

yep as a rough measurement, not as easy as an ASET image but you can tell if it has a lot by the leakage dots at the top of the uppers being smaller than expected for that combo or fully closed.
Also common there will be one or 2 that looks different than the rest because of painting or digging on a few facets. There have been a lot of these lately in various vendors stock.

 

[WinkHPD]

Kobi/pfunk,
You are both level-headed independent thinkers and I cannot disagree with your logic. You have done alot of good research and you are comfortable with making slight compromises in cut precision by virtue of the fact that the diamonds will still be beautiful and that the deficits may not be readily apparent in real life. The position that I see you both gravitating towards is that stepping up from ideal to super-ideal delivers a diminished return on the extra investment that might be better spend on another C. Every diamond buyer has to weigh many factors and plenty of people do come to this conclusion.

But I disagree with the sentiment that it is somehow wrong for consumers to be encouraged to seek elite cut quality. In some circles the pendulum may have swung back past nuetral, but one of the historical problems with the diamond market is that there have been too many voices for compromise in cut quality. That has led to a situation where for over a hundred years the market has been overstuffed with mediocre cuts, depriving consumers from enjoying the full magnificence of the diamonds they have purchased.

The information age has only recently begun to change the dynamic. But those new voices that we are starting to hear are changing the way manufacturers approach their craft and the result is increasing availability of finer crafstmanship and more beautiful diamonds for everyone to choose from. I think those voices should be encouraged.

While it might sound a bit self-serving to some, I truly believe it's better for the entire market if those in a position to educate and guide consumers err on the side of top precision and light performance.

I could not agree more. In fact, although the market is much better served today than it used to be, there is still a TON of drek being served up to uneducated buyers.

I have bolded your last sentence because I agree with you that it is better to err on the side of better.

I all go further in stating that I too do not believe it to be an error since in "blind taste tests" where three or more diamonds are placed in a slotted tray with nothing being said, the better cut diamonds are overwhelmingly the ones chosen by the person looking at the diamonds.

This is not to say that the diamonds not chosen are "hideous or ugly," only that they are not found to be as beautiful as the top cut diamond. Since I will not even show an ugly diamond, this means that the diamonds not chosen were also beautiful, just not as beautiful.

Since we are often choosing these diamonds to be a symbol of the love and respect that we have for the recipient, why would we not then choose that diamond that we most believe has EVERYTHING WE CAN GET in terms of beauty?

Yes, when it is not side by side with the winner of that "blind taste test" we may not see the difference, but we will always know that we cheaped out, thus lessoning our own attachment to the diamond that we gave.

I would not buy a diamond for my wife that was not "All that it could be" in terms of cut, so I prefer not to even offer them for sale anymore. I have long ago drunk the Cool Aid, and I like the taste better every day.

Thus, for me, it is written.
Thus, for me, it shall be done.

Wink

 

[Texas Leaguer]

Kobi/pfunk,
You are both level-headed independent thinkers and I cannot disagree with your logic. You have done alot of good research and you are comfortable with making slight compromises in cut precision by virtue of the fact that the diamonds will still be beautiful and that the deficits may not be readily apparent in real life. The position that I see you both gravitating towards is that stepping up from ideal to super-ideal delivers a diminished return on the extra investment that might be better spend on another C. Every diamond buyer has to weigh many factors and plenty of people do come to this conclusion.

But I disagree with the sentiment that it is somehow wrong for consumers to be encouraged to seek elite cut quality. In some circles the pendulum may have swung back past nuetral, but one of the historical problems with the diamond market is that there have been too many voices for compromise in cut quality. That has led to a situation where for over a hundred years the market has been overstuffed with mediocre cuts, depriving consumers from enjoying the full magnificence of the diamonds they have purchased.

The information age has only recently begun to change the dynamic. But those new voices that we are starting to hear are changing the way manufacturers approach their craft and the result is increasing availability of finer crafstmanship and more beautiful diamonds for everyone to choose from. I think those voices should be encouraged.

While it might sound a bit self-serving to some, I truly believe it's better for the entire market if those in a position to educate and guide consumers err on the side of top precision and light performance.

TL, thanks for keeping a presence in this thread. I always find your responses to be very well thought out and genuine. I realize this has taken somewhat of a turn to a discussion of ideal vs super ideal but that was not my intent. I do not mean to diminish the added benefit of stepping up to a super ideal cut diamond or to say that it is not worth it to certain consumers. Without a doubt it is, and I have seen many consumers asking for that level of precision. Also, we as consumers are very lucky to have people like yourself demanding that cut quality be an expectation and not a luxury. There are so many beautiful diamonds available because of the push that you and others have made to bring cut quality to consumers. Thank you for that.

What I question is how often consumers are swayed from diamonds that have great numbers and pushed towards only the diamonds with a wealth of information (ideal scope, aset, hearts images). Rarely can you find diamonds with all of this info unless you are looking at the super ideal cuts. That information is great to have and so reassuring for consumers, but it doesn't mean the next diamond that is cut to ideal proportions but lacking an idealscope image is any less beautiful. While performance is likely to diminish at the edges of the ideal range, especially when being measured by sophisticated computers, it doesn't mean that the diamond isn't going to be beautiful to people. I would argue the great majority of consumers here would still find such a diamond (edge of ideal with some leakage) beautiful. Instead, they seem to be told that they stand to give up a great deal in performance by straying from perfection. Enough so to be readily apparent to the average consumers eye. That is what I question.

pfunk,
First of all, thank you for those comments. That means alot to me.

Regarding the part I bolded, this is very much related to my commentary. With the chorus of voices in favor of precision cutting growing, along with increasing availability of information technologies to capture and share supplemental analytics, combined with the emergence of a new generation of consumers who are data driven and self-educating, more and more merchants are beginning to see the value in making this information available. We are now seeing merchants provide photos, videos and reflector images of a whole range of diamond qualities - not just super ideals. This is a rapidly growing trend and a really good development for the consumer.

Consumers should not have to guess or hope that their diamond will provide the performance they want, simply because the leading laboratory does not provide detailed enough analysis in this area. They should have all the information they need to make the decision that is right for them.

We are definitely moving in the right direction. As more of the diamonds coming to market are presented with comprehensive analysis, I believe you will see prosumers recommending a wider range of diamonds based upon posters stated goals and preferences. (you don't have to look at too many threads to see this is taking place already). But in the absence of full "illumination," I think there is a natural tendency to recommend the known over the unknown. And in a forum where there are many who are passionate about diamonds cut for optimal beauty, it should come as no surprise that opinions and guidance given would be biased in the direction of precision cutting.