Lord Summerisle
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Are the hearts & arrows cut diamonds just a fad?
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JohnQuixote
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M'Lord, right and wrong.
Right: The reference was to physical/optical symmtery, not lab graded symmetry. Info on the difference, here.
Wrong: Garry is not a H&A fan. He is a fan of great cut. This is often the same path.
Cut lovers embrace optical symmetry because good patterning makes for robust light return. However, Garry often volunteers that a H&A level of symmetry may not eclipse other diamonds with great cut.
Actually, I was of the opinion that he voices this over-frequently (in order to separate himself from the techno-patterning pundits), but perhaps he hasn't.
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100% on the money John.Date: 7/16/2005 8:26:04 PM
Author: JohnQuixote
M''Lord, right and wrong.
Right: The reference was to physical/optical symmtery, not lab graded symmetry. Info on the difference, here.
Wrong: Garry is not a H&A fan. He is a fan of great cut. This is often the same path.
Cut lovers embrace optical symmetry because good patterning makes for robust light return. However, Garry often volunteers that a H&A level of symmetry may not eclipse other diamonds with great cut.
Actually, I was of the opinion that he voices this over-frequently (in order to separate himself from the techno-patterning pundits), but perhaps he hasn''t.
AGS are still considering making a H&A''s or (i guess) Super Ideal Catagory.
But I like people to remeber that there are H&A''s that are too leaky Step Deep etc
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diamondsbylauren
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Interesting.
GIA says "Very Good" symmetry, Garry says it "Sucks". Hmmmmm. Who to believe? GIA or Garry. GIA or Garry.
Remember GIA examined the diamond, and after all, they ARE GIA- I think it would be reasonable, to assume GIA is the informed party here.
Garry- are you saying then, that you do not believe GIA to knows what they are doing?????
GIA says "Very Good" symmetry, Garry says it "Sucks". Hmmmmm. Who to believe? GIA or Garry. GIA or Garry.
Remember GIA examined the diamond, and after all, they ARE GIA- I think it would be reasonable, to assume GIA is the informed party here.
Garry- are you saying then, that you do not believe GIA to knows what they are doing?????
Lord Summerisle
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strmrdr
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talking about different things:
There are 3 types of symmetry that the cut nuts talk about here:
Physical - measured using the sarin,helium and ogi machines and is how close to the same size and angle the like facets are to each other.
optical - measured using hearts and arrow viewers and is how close to being alike the optical patterns of the diamonds facets are to each other.
meet point - measured using a loupe is how well the meet points line up and how the meet points look. This is what the Labs report for the symmetry grade.
What we are talking about being poor is the physical symmetry of the diamond in question.
The facets vary and because of the quality of the image we cant measure all of them using diamcalc to get a good average.
This is why using diamcalc I couldn''t nail down the numbers and why the answers will vary a lot.
On diamonds with very good to excellent physical symmetry it is easy to figure out the proportions using diamcalc on diamonds with fair to poor physical symmetry its pretty much impossible.
Especially with a bad image where some of the patterns the facets show arent visible in the image.
diamondsbylauren
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A- HA!
Here we have stumbled on something.
If a diamonds facet''s hook up correctly, they do not neccesarily need to match each other to earn a VERY GOOD from GIA regarding the SYMMETRY.
I agree with this statement.
Now, if GIA feels the SYMMETRY of the diamond is Very Good- after having observing the difference in certain facet sizes- what does that mean?
When were talking about "facet matching", that is to say, star facet #24 matches star facet #26 ( if diamonds facets were numbers in such a way).
That tells us that GIA does NOT agree with the assumptions of strmdr and garry regarding the importance of "facet matching" per se. I agree with GIA.
Garry and Strmdr are you saying you guys disagree with GIA????
Here we have stumbled on something.
If a diamonds facet''s hook up correctly, they do not neccesarily need to match each other to earn a VERY GOOD from GIA regarding the SYMMETRY.
I agree with this statement.
Now, if GIA feels the SYMMETRY of the diamond is Very Good- after having observing the difference in certain facet sizes- what does that mean?
When were talking about "facet matching", that is to say, star facet #24 matches star facet #26 ( if diamonds facets were numbers in such a way).
That tells us that GIA does NOT agree with the assumptions of strmdr and garry regarding the importance of "facet matching" per se. I agree with GIA.
Garry and Strmdr are you saying you guys disagree with GIA????
strmrdr
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You got it.
Yes the size and angle of 2 star facets matching would be part of physical symmetry.
How they work in relation to the other facets in forming the h&a patterns would be optical symmetry.
I dunno if if I disagree with GIA or not.
They haven''t seen fit to give me enough information on the new cut grade system to determine that.
Under the old system it wasn''t reported because they apparently didnt take it into consideration.
JohnQuixote
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Hey David,
Did you read the synopsis in the link I provided near the top of the page?
(click here)
At the bottom is another article by Serg, Yuri and GH that goes into further detail.
This is VERY pertinent to this thread. It is something Brian Gavin has been up-in-arms about for years. Many labs (not just GIA) grade meet-points and a modicum of indexing. But they do NOT take into account how the mirrors in a diamond actually align with each other... Kind of important, don't you think?
Many people are under the mistaken assumption - or are told - that a diamond with EX/Ideal in 'symmetry' means that the facets are all optimally aligned with each other, when it doesn't mean that at all.
It's wonky.
diamondsbylauren
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John- I did look at the page and there were assumptions made which I did not feel were in line with GIA''s actual policy.
I agree with GIA- I do not feel that the exact positioning of the "mirrors" must be aligned to produce a beautiful diamond.
I do agree that if you are looking for a Hearts and Arrows pattern the placement is critical.
I just don''t agree that the pattern makes a "better" diamond.
Apprarently ( by thier actions thus far) GIA agrees-
I''ll bet they address this in the new cut grade- but I''d also bet they won''t call diamonds "better" just because they exhibit this pattern.
I agree with GIA- I do not feel that the exact positioning of the "mirrors" must be aligned to produce a beautiful diamond.
I do agree that if you are looking for a Hearts and Arrows pattern the placement is critical.
I just don''t agree that the pattern makes a "better" diamond.
Apprarently ( by thier actions thus far) GIA agrees-
I''ll bet they address this in the new cut grade- but I''d also bet they won''t call diamonds "better" just because they exhibit this pattern.
JohnQuixote
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David, I'd appreciate it if you could elaborate on the assumptions. I welcome input.
Critical is correct. For a true H&A level of patterning the placement and alignment necessary to line up the reflecting mirrors is extraordinary. 6 different facets must be in precise alignment in the pavilion to create just 1 of those completely focused 'hearts' patterns - and every facet overlaps in its duties.
Even if not so completely locked in, robust placement & alignment of the mirrors improves light return in any diamond. This becomes most apparent in non-direct light conditions, since most look good in halogens regardless of cut precision: In direct lighting you are seeing sheer volume of light returned, not fine-tuning, which shows up in diffuse and especially in soft lighting.
And David, I didn't use the words beautiful or better - here or in the synopsis regarding symmetry. These are technical issues, not taste issues.
diamondsbylauren
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Sorry John- I never meant to put words in your mouth.
I really appreciate the conversation and the way you are approaching it-
I'll be the first to say John is a gentleman and a class act!
Here's the statement I took issue with- it is the third line down on the page
I've never seen such a statement issued by GIA.
In fact, I agree- if you are looking at a diamond without a loupe, you could never see the difference between Good, Very Good, an Excellent GIA symmetry grade - and it takes careful examination to see the difference with a loupe.
I've just never seen GIA make the conclusion you stated.
AS far as facet placement- yes- it is very important- and my points about a larger table hiave to do with the fact that it's easier to align the facets with a larger table.
I think that's part of the great aspects of the Ideal cut Hearts and Arrows.
You are focusing the light from the bottom of the diamond up through a smaller window.The resultant stone gives great fire. I like hearts an arrows ideal cut stones too.
It's true that in softer lighting conditions the cut becomes even more critical- a well cut 60/60 will show well in softer lighting conditions too.
I really appreciate the conversation and the way you are approaching it-
I'll be the first to say John is a gentleman and a class act!
Here's the statement I took issue with- it is the third line down on the page
I've never seen such a statement issued by GIA.
In fact, I agree- if you are looking at a diamond without a loupe, you could never see the difference between Good, Very Good, an Excellent GIA symmetry grade - and it takes careful examination to see the difference with a loupe.
I've just never seen GIA make the conclusion you stated.
AS far as facet placement- yes- it is very important- and my points about a larger table hiave to do with the fact that it's easier to align the facets with a larger table.
I think that's part of the great aspects of the Ideal cut Hearts and Arrows.
You are focusing the light from the bottom of the diamond up through a smaller window.The resultant stone gives great fire. I like hearts an arrows ideal cut stones too.
It's true that in softer lighting conditions the cut becomes even more critical- a well cut 60/60 will show well in softer lighting conditions too.
Rank Amateur
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I always found it odd that the labs usage of the word "symmetry" is different from the rest of the world. For something to be "symmetrical", one side should be opposite hand and identical. Who cares whether the corners meet if the facets don't align?
I'll bet the GIA would give Lyle Lovit's face an "excellent" symmetry grade.
I'll bet the GIA would give Lyle Lovit's face an "excellent" symmetry grade.
JohnQuixote
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David, no apology necessary at all. Thanks for the kind words. Consider them returned along with appropriate respect for my elder.
The GIA conclusion came last year as they were working to build their new system. Garry covered it - and a cornucopia of other info - in a November journal article: "A review of the foundation of GIAs new cut grade system."
Here is a graphic from page 10 of the article. Notice it says ‘no effect’ for all three - G, VG and Excellent - but since that time it's been revised to only VG and EX, as they found naked eyed experts who could sometimes detect lower symmetry in diamonds receiving Good or lower (I went and revised that in my synopsis - danke).
GH could give you more info I am sure.
JohnQuixote
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diamondsbylauren
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John- the "study" and graphic you posted were written by Garry Holliway, not GIA.
Garry has expressed a didain for GIA in this very thread- I menton this to put things in context.
I''d like to see GIA themselves issue such a statement- I mean to say- I don''t think GIA ever would.
I''m 48 John- in spite of the fact I look 70
.
Garry has expressed a didain for GIA in this very thread- I menton this to put things in context.
I''d like to see GIA themselves issue such a statement- I mean to say- I don''t think GIA ever would.
I''m 48 John- in spite of the fact I look 70
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Great thread.
Strm... excellent synopsis on the various aspects of symmetry.
The question that begs an answer ... and think about this Dave ... At the end of the day, which impacts the diamonds appearance more than any other? Physical, optical or meet point? It is true that physical and meet point will ultimately impact the optical symmetry in some manner but which of the 3 affect face up appearance most?
If you would like to discuss the subject of optical symmetry further and delve a little deeper into the minds that talk about it around here this would make for interesting discussion if you don''t fully grasp the concept of optical symmetry (ultimately the results of both proportions and symmetry (physical & meet point).
On another note Dave, some food for thought and a question. If a diamonds facets are to function as reflective surfaces of light (pavilion facets functioning primarily in a role of "mirror" rather than "window") but certain known crown angles produced more windows off the pavilion and less mirrors ... which would you rather have those pavilion facets function as? Mirrors or windows?
Strm... excellent synopsis on the various aspects of symmetry.
The question that begs an answer ... and think about this Dave ... At the end of the day, which impacts the diamonds appearance more than any other? Physical, optical or meet point? It is true that physical and meet point will ultimately impact the optical symmetry in some manner but which of the 3 affect face up appearance most?
If you would like to discuss the subject of optical symmetry further and delve a little deeper into the minds that talk about it around here this would make for interesting discussion if you don''t fully grasp the concept of optical symmetry (ultimately the results of both proportions and symmetry (physical & meet point).
On another note Dave, some food for thought and a question. If a diamonds facets are to function as reflective surfaces of light (pavilion facets functioning primarily in a role of "mirror" rather than "window") but certain known crown angles produced more windows off the pavilion and less mirrors ... which would you rather have those pavilion facets function as? Mirrors or windows?
JohnQuixote
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Date: 7/17/2005 11:35:19 PM
Author: diamondsbylauren
John- the 'study' and graphic you posted were written by Garry Holliway, not GIA.
Garry has expressed a didain for GIA in this very thread- I menton this to put things in context.
I'd like to see GIA themselves issue such a statement- I mean to say- I don't think GIA ever would.
I'm 48 John- in spite of the fact I look 70.
David - I'm twisting your tail
I believe (Fall) 2004 G&G may have included the symmetry judgments Garry reported in their foundation article (?) but it's not at my fingertips and not online. I did find GIA's clarification of lab-graded versus optical symmetry on their Cut Research Technical FAQ
How does “optical symmetry” relate to the symmetry that GIA currently reports, one aspect of finish?
To understand this issue, in fact three different meanings of symmetry need to be explored here: mathematical (or modeling) symmetry, grading (or physical) symmetry, and “optical symmetry.” These different meanings have different implications.
* A computer modeled, or virtual, diamond has “perfect” mathematical symmetry – all facets of a given type are evenly spaced around the outline and have exactly the same angle to the horizontal. All facets are perfectly flat, are shaped correctly, and relate perfectly to each other. The relationships of the facets in three dimensions (3D) are displayed well in most two-dimensional (2D) projections.
* The symmetry of a real diamond is graded for finish by examining the diamond’s surface, identifying major and minor symmetry faults (like table-off-center, misalignment between crown and pavilion, or a misshapen bezel), and assigning an evaluation. Multiple symmetry faults can interfere with each other such that some kinds of 3D mis-orientation (that is, 3D skew) are not easily seen from any single 2D view.
* Optical symmetry requires a special viewing device that surrounds the diamond. The light passes through the diamond and interacts with the viewing device to create a pattern, either face-up or face-down, for the observer. The consistency and balance of this pattern results from the 3D symmetry of the diamond; the exact appearance of the pattern is related to the proportions of the diamond. Some kinds of 3D skew that are not easily observed on the surface of the diamond are revealed by the lack of optical symmetry. In addition, some corrections of 3D skew leave minor (finish grading) symmetry faults on the surface of the round brilliant.
In other words, there is not always a direct relationship between optical symmetry and graded (surface) symmetry, so that a diamond with high optical symmetry does not necessarily also have excellent graded (surface) symmetry, and vice versa.
JohnQuixote
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Another FAQ item on that GIA site pertinent to this thread.
If a diamond looks better in one of the proprietary viewers (such as one of the “hearts and arrows” viewers), does it get a better grade in the GIA System? Did observation tests confirm that such diamonds look better?
Many people in the trade use the term “optical symmetry” in referring to “branded” diamonds that show near-perfect eight-fold symmetry by displaying eight “hearts” in the pavilion-up position, or eight “arrows” in the face-up position, when viewed in specially designed optical viewers. To investigate the possible benefits of optical symmetry, we included several such diamonds in our observation testing. We found that although many diamonds with optical symmetry received high observation scores, other diamonds (with very different proportions and, in many cases, no discernable optical symmetry) were ranked just as highly.
An interesting by-product of the testing was that those trade members who emphasized this type of diamond in their business generally chose such a diamond as the highest ranking (although not always). Those who did not market this type of diamond chose it as best about as often as they chose other diamonds we have placed in the top grade categories. It appears that these types of diamond could be likened to an “acquired taste” or “learned bias.” This doesn’t mean that some of them shouldn’t rank highly—it just means that not everyone agrees.
Finally, there are a variety of proportions that yield these patterns, some of which cause the diamond to appear darker to many observers. When a diamond had such a dark appearance, even though the pattern was considered a very good representation of a diamond with “optical symmetry,” many observers did not place it in the top category. This has been accounted for in our system.
If a diamond looks better in one of the proprietary viewers (such as one of the “hearts and arrows” viewers), does it get a better grade in the GIA System? Did observation tests confirm that such diamonds look better?
Many people in the trade use the term “optical symmetry” in referring to “branded” diamonds that show near-perfect eight-fold symmetry by displaying eight “hearts” in the pavilion-up position, or eight “arrows” in the face-up position, when viewed in specially designed optical viewers. To investigate the possible benefits of optical symmetry, we included several such diamonds in our observation testing. We found that although many diamonds with optical symmetry received high observation scores, other diamonds (with very different proportions and, in many cases, no discernable optical symmetry) were ranked just as highly.
An interesting by-product of the testing was that those trade members who emphasized this type of diamond in their business generally chose such a diamond as the highest ranking (although not always). Those who did not market this type of diamond chose it as best about as often as they chose other diamonds we have placed in the top grade categories. It appears that these types of diamond could be likened to an “acquired taste” or “learned bias.” This doesn’t mean that some of them shouldn’t rank highly—it just means that not everyone agrees.
Finally, there are a variety of proportions that yield these patterns, some of which cause the diamond to appear darker to many observers. When a diamond had such a dark appearance, even though the pattern was considered a very good representation of a diamond with “optical symmetry,” many observers did not place it in the top category. This has been accounted for in our system.
diamondsbylauren
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BINGO John!!!!
I would say that using excerpts from GIA publications along with interpretive analysis makes a lot of sense- as opposed to simply summarizing without including the original text as reference.
This section deals with optical symettry and it''s effect on a diamond''s appearance.
It confirms some things I''ve been talking about-I read it to say that if one is used to something, that''s what you like to look at.
I learned to grade diamonds using 60/60 as a model- that''s what''s familiar.
Those that learned about cut using stones with excellent optical symmetry would look for that.
The section above seems to confirm that man people will chose stones with no optical symmetry in many cases.
diamondsbylauren
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Hey Rhino!
Good to see you- an I welcome the discussion.
I was not aware of the concept of optical symmetry- and now that I''ve read up on it it makes perfect sense in relation to Heart and Arrows.
The discussion of GIA''s analysis is a great starting point.
My contention has always been:
Patterns in diamonds ( which would indicate optical symmetry) are beautiful, but not inherently better or more sprkley than diamonds with disorganized sparkle.
TO answer yoour question about mirror/window.
In most cases, it could be said that wondowing is a negative effect- you don''t wan''t to be able to see "thru" your diamond.
In fact, it is possible for facets to behave as winows one instant and mirrors the next.
Simply because it''s not possible to hold a diamond totally still when wearing it.
If certain if the star facets are on the borderline and they can switch between mirror and window, the effect can be dazzling.
SO yes, I agree- optical symmetry is eseential in all kinds of Hearts an Arrows Diamond- and that this aspect can be extremely desirable to many observers.
GIA''s conclusions are that observers also found many diamonds without optical symmtry to be ranked just as highly.
JohnQuixote
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Yes sir. It also confirms some things I have been saying.
This is the position both GIA and AGS currently take on optical symmetry. No surprise. Any official preference for one over the other would tilt the industry. Straddling the middle is the most politically correct position, and it neatly accounts for range of taste in humans.
ETA - I'd note that these studies were done in jewelry store lighting and grading conditions, not in softer lighting where H&A type optimization really stands out. It's also funny that they used 'trade members' in the study (who seemed to prefer what they sell...there are some implications there of course). Among them, the H&A pundits generally selected H&A as their top choice, while non-H&A people chose H&A 'about as often' as they did not.
The explanation of your beginnings makes perfect sense.
I began as a clueless consumer some years ago. I had no 'acquired taste' (except for my hyperobsessive-compulsive-overanalytic nature...thanks mom & dad). I just knew I wasn't getting answers that made sense at the mall. After months of exposure to pedestrian quality goods I had the opportunity to directly compare 60/60 & non-ideals with Tolkowsky ideals and superideals. The impact that experience made on me is what led me, ultimately, to leave my previous field to pursue this. I see the same kind of impact in customers' eyes when they come in for the tour.
So...You prefer what you first came to value in the trade. I came to my values on a different path. These, of course, are matters of taste and are as logical as digging your mom's cooking - except this costs a bit more.
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diamondsbylauren
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Hey Garry!
No, I did not forget.
I have already had an OGI drawn on the diamond.
I will send it up to the Diamond Club here in NYC to have a Sarin drawn.
I don''t know which 3D- or other type they have there.
A question Garry:
DO you feel it''s possible to measure a diamond using a Sarin twice, and get EXACTLY the same results both times?
No, I did not forget.
I have already had an OGI drawn on the diamond.
I will send it up to the Diamond Club here in NYC to have a Sarin drawn.
I don''t know which 3D- or other type they have there.
A question Garry:
DO you feel it''s possible to measure a diamond using a Sarin twice, and get EXACTLY the same results both times?
diamondsbylauren
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Here''s the reports.
They were drawn on the same machine ( located on the NYC Diamond Dealers Club in NYC)
And the GIA
AS we can see- this is pretty close to the GIA table number. Measuring tables is no siomple task- and actually, it is an estimation.
The crown angles of 35.3 is well below any of the estimations. Garry''s got two at 38.76%
John wrote:
Then Rhino noticed that people were using the incorrect measurements.
SO- let''s just say no one got anywhere near the actual angles of the diamond- and these are crucial to the way it looks.
If a diamond has "Crown Angles" which are too steep, it looks bad.
You don''t need to be an expert to notice a round diamond with 38.75% crown angles- it would look ungainly to anyone who knows what a diamond is supposed to look like.
Old Miner cuts, OEC cuts Cushion cuts- all have these steeper angles- many of them pull it off, and look quite attractive.
Looking over the entire thread- which I just did- I would emphasize that I do NOT believe Hearts and Arrows are in any way a fad.
It''s a preference- and the people who sell these stones, and specialize in them, posses special tools and knowledge.
I respect them, and the people who love this type of diamond.
If you''re looking for such a stone, it''s easy to find out who''s prepared to provide what you seek.
If you walk into a store, and they never heard of Hearts and Arrows, or they try to tell you bad things about them, move on.
Thank you everyone who''s participated.
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diamondsbylauren
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Past, Present, Future: The Meaning of Three-Stone Engagement Rings
Past, Present, Future: The Meaning of Three-Stone Engagement Rings - 04/14
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