How the number of chevron facets change the character of a princess-cut

[Paul-Antwerp]

Date: 11/12/2006 9:25:00 AM
Author: He Scores

Date: 11/12/2006 8:24:18 AM
Author: Paul-Antwerp

Date: 11/10/2006 12:36:20 PM
Author: Cehrabehra

Date: 11/10/2006 9:55:37 AM
Author: Rhino

I agree Cehra. The thing is I don''t think most folks care about the number of chevrons perse as most princess cuts on the market (including AGS Ideals) primarily consist of 3-4 chevron pavilions. The more folks get educated on the subject however and view them, only then will demand increase for one style over another. The folks we''ve showed this comparison to have been a pretty even split that I can recall. Perhaps I should hold a survey (once Tim gets back from vacation) and tally up to see where most consumer preference lies with this?

Peace,

Yeah but Jon, most folks (aka consumers) don''t care about almost *anything* we talk about here LOL!! When I got here I found it frustrating to be told right off the bat ''Educate yourself!'' and to quickly find that that education really was reserved for rounds. When the consumers decide to know, it should be available for them TO know. We shouldn''t just assume that because right now they don''t even know the difference between a princess and an asscher, that when they DO decide they want to know more, they shouldn''t have good access to the difference between a 2 and 4 chevron princess and what that means.

As this particular post is my 1''000th post on PS, I took the time to contemplate what its subject should be. And of everything I have read here in the past days, the above highlighted sentence is a good candidate for ''observation of the year''.

We should indeed realise that most knowledge on cut and most cut-grading tools are based upon the study of round brilliants. At the same time, we should realise that a round brilliant is a rather standardised cut (with a specific faceting pattern) and with cut-quality historically centering around one specific set of proportions (Tolkowsky). As such, it is rather easy to study, but it is very dangerous to automatically apply the acquired knowledge to fancy-cuts.

As this thread shows, in princess-cuts, there is no standardised faceting-pattern, and there clearly is no historic centering-point. The same is true for other fancy shapes, but I need to add, that since we did not venture into cutting these, my knowledge of these is close to zero. May I repeat this: ''You may consider me a diamond-expert, but as an expert, I tell you that I currently know close to nothing about other cuts than round brilliants or princess-cuts.''

Because most studies concentrate on rounds, most of the tools for rounds do not necessarily work for princess-cuts. This is true for idealscope, and even a ASET-photograph gives me insufficient info. Like Jonathan mentioned, to show the difference in character between 2 and 3-line-chevrons, photographs did not suffice, and only video could show part of the difference.

Also, a machine like the Brilliancescope will have more problems with 2-line-chevron-stones, because where one has intenser, but fewer flashes, a machine tested on rounds has a higher possibility of missing these, and of thus screwing up the assessment.

All this to thank you for voicing your frustration and to celebrate my 1''000th post.

Live long,

Paul,
I admire your humbleness.

I was taught my trade by a man who specialized in fancy shapes and fancy colors. I was taught that the ''beauty of a fancy shape is in the shape.'' To buy a fancy for brilliance is counter productive. The Brilliant is so called because it is that. The most brilliant. The more one deviates from a round the greater the loss of briliance. Straight edges are the least brilliant of all diamonds. When I say brilliant, I''m referring to the reflection of the spectral colors and a good degree of surface reflection from each individual facet. The most popular fancy would likely be a heart of a squatty oval since they lend themselves most closely to a round, but they are far from being the most popular shape. Over my 30 years in the business, the MQ was and the Princess cut now is the most popular fancy. Neither being the most brilliant of diamonds. So much for performance from the standpoint of brilliance. Their is a big difference as we have seen in how well stones like this are made. Workmanship!

This is why, the majority of diamonds cut are rounds, and this is why I agree with your statement highlighted above that assigning brilliance quantification to fancies is erroneous. However, as I pointed out, the making of all diamonds from the cutter''s workmanship by placing one facet on at a time is VERY SIMILAR and in most cases has measurable results that can be evaluated for accuracy.

The complications that arise however are that which of the elements of this facet making are more important than others. One has to be able to separate characteristics of the stone which are individual taste, or are a result of the facet making process rather than facet evaluation in itself.

Bill Bray
Diamond Cutter

Hey Bill,

On the contrary, I am a strong supporter of using Brilliance and other factors of light performance as a means to judge the cut of fancy-shapes.

I am saying that all studies and tools on the subject of light performance concentrate on rounds, and that the resultant tools do not work on fancy shapes.

Big difference,

 

[Paul-Antwerp]

By the way, the name ''brilliant'' has become very popular to make a distinction with the word ''diamant'' (in English diamond), which was used for a round 8-cut 17-facet diamond, where on the European consumer-level, the impression was created that a brilliant was more valuable than a ''diamant''.

Still today, I often meet older European consumers, who swear that their ring does not have diamonds, but brilliants, and that this is much more valuable.

On another note, big-size-princess-cuts apparently can exhibit more brilliance than a round. That is what I learned from Garry anyway.

Live long,

 

[strmrdr]

Date: 11/12/2006 9:33:39 AM
Author: Paul-Antwerp
Hey Bill,

On the contrary, I am a strong supporter of using Brilliance and other factors of light performance as a means to judge the cut of fancy-shapes.

I am saying that all studies and tools on the subject of light performance concentrate on rounds, and that the resultant tools do not work on fancy shapes.

Big difference,

Paul,
I see where your coming from, Im not sure I agree that its that cut and dried.
I think for the most part the tools will work atleast some what, mainly its the knowledge to interpret the results that is lacking.
For example I feel the aset is the best tool available for showing the performance of asschers and EC.
While the IS can give misleading results with some angle combinations on EC/SE but work very well with others.
helium/DC combo works pretty good for any shape Iv seen.
The b-scope is pretty useless on EC/SE cuts and can lead to bad conclusions so your right there.
As far as princess cuts go I dont know or care much how well the tools work on em so you could very well be right on them.

 

[oldminer]

The shape, the beauty of the outline, of some fancy cuts is a key element to their appeal to the eye. I think this applies more to pear, marquise, heart and oval than it does to the straight sided ones, such as princess, radiant and emerald cut. The straight sided stones depend on right angles, symmetry and purity of shape, not soft, curving features.

Nearly all diamonds today are cut to show brilliancy, sparkle and intensity in abundance. Modern rose cuts and very shallow, spready stones are the primary exceptions.

Once we measure brilliancy, sparkle and intensity, and also analyze the factors of outline shape, and cut craftsmanship, we can grade the "cut quality" of any shape diamond. No one cuts a diamond to be dull and lifeless on purpose unless it is impossible to get a better stone. No one cuts an ugly outline unless it is the only way to go which makes financial sense.

You can have nearly 100% brilliancy with a mirror, but it won''t be beautiful like a diamond ought to be. Having more "brilliance" in a rare princess than a round cut is okay, but it will have less sparkle or intensity possibly, and it might not actually be such a wonderful looking stone even with high brilliancy. That''s why three variables are being measured instead of one when it comes to light performance. If it only took one variable to know how good a diamond performed, why measure three? We need three, and they work in a complex way, but they work together. Brilliancy alone is not a measure that will insure a beautiful result.

I believe you can measure craftsmanship and light behavior on all diamonds with similar measures. You must add in the beautiful outline factor for curved sided fancies and the symmetry required on right angle fancy stones. It isn''t a huge problem, but the traditional view of "only Tolkowsky", is definitely going away or being modified.

 

[Paul-Antwerp]

There is a difference between the business of grading and that of choosing a stone (like a consumer) or choosing for a specific cutting-design (like a cutter).

And the premise of this thread is that one cannot make a distinction between different designs of princess-cuts in grading, while there is a big difference in character, look, flavour or whatever you like to call it.

I am not saying that this is bad. It is just extremely important for consumers to know.

Live long,

 

[Cehrabehra]

Date: 11/12/2006 8:24:18 AM
Author: Paul-Antwerp

All this to thank you for voicing your frustration and to celebrate my 1''000th post.

Live long,

congratulations Paul! And thank you for your contributions

 

[Garry H (Cut Nut)]

Nice thread Paul, and a good discussion everyone.

A couple of thoughts:

The optimum # of chevrons is as complex as whether to paint or dig - it depends on factors such as the relationships between table size, crown angleS and the 4 triangular pavilion angles and the 4 mian corner to culet angles - sometimes 3 is too many with smaller tables, and 4 is not enough in a big stone with a smaller table and less angular difference between the 2 types of pavilion angles. It is easily possible to have a small under 1/2ct stone with far too many chevrons - most stones on the market today have this wrong - so not a lot of cutters ''think'' about this - they ''just do it'', and do not desrevre a tick either!

You can make Diamcalc models that show this either way.

Date: 11/10/2006 12:46:18 PM
Author: Cehrabehra

Date: 11/10/2006 10:39:54 AM
Author: Rhino

I agree. Here''s the comparison of the AGS graphic as compared to an actual scan of the stone. What you say above is right on, about double the size.

okay, so WHY can''t GIA and AGS put actual scans of the stones on their certs rather than those generic facet plots which usually but don''t always accurately tell the story? (okay so the # might be accurate but not placement)

The answer is most scanners have a very hard time reading the sometimes few degree differences between chevrons and miss entire facets. But it would be a great thing if they would C!!!

it would be also very good for Sergey''s Helium sales.

But an even worse thing is what some labs call these diamonds. Why oh why cant they call a spade a spade?

 

[Cehrabehra]

Date: 11/12/2006 8:17:37 PM
Author: Garry H (Cut Nut)
Nice thread Paul, and a good discussion everyone.

Date: 11/10/2006 12:46:18 PM
Author: Cehrabehra

Date: 11/10/2006 10:39:54 AM
Author: Rhino

I agree. Here''s the comparison of the AGS graphic as compared to an actual scan of the stone. What you say above is right on, about double the size.

okay, so WHY can''t GIA and AGS put actual scans of the stones on their certs rather than those generic facet plots which usually but don''t always accurately tell the story? (okay so the # might be accurate but not placement)

The answer is most scanners have a very hard time reading the sometimes few degree differences between chevrons and miss entire facets. But it would be a great thing if they would C!!!

it would be also very good for Sergey''s Helium sales.

But an even worse thing is what some labs call these diamonds. Why oh why cant they call a spade a spade?

most, huh??? if the helium works so well, why the heck NOT make it a standard?

yanno, I have had a passion for floorplans for over 20 years.... every home blueprint or floorplan I get my hands on I inspect and scour - not *as* interested in elevations.... but on diamonds I have the same fascination with facet plots, particularly with cushions because they offer me the most variety, but really - anything with a facet issue fascinates me!

if technology isn''t ready to provide these on every cert, why the heck not push for it? that''s my vote!

I got lost on that last sentence - yikes, not even the first time lol

 

[Garry H (Cut Nut)]

Date: 11/13/2006 1:12:52 AM
Author: Cehrabehra

most, huh??? if the helium works so well, why the heck NOT make it a standard?


if technology isn''t ready to provide these on every cert, why the heck not push for it? that''s my vote!

Ever heard of Not Invented Here syndrome?

Sergey is Russian

helium has fast become the new standard in india where Russian''s are not seen as threatening.

The main US labs we discuss here have 1 or 2 Helium Polished.

AGS use their Helium when the model builds are not good enough for their 3D scanning software, but a little bad scan here or there does not worry them - but the scans would rarely be good enough for printing on reports.

Helium takes a little longer to run a scan, and that is the main reason the labs give, as well as they already own the other scanners.

 

[oldminer]

Predictions of light behavior based on 3D and facet measurements are not the way to "grade" light behavior. No "grading" is based on a predictve model when direct measurement may be accomplished. This is not a rule only for diamonds, but a general scientific principle. No one has ever given us an example to show this statement is incorrect.

You don''t weigh a diamond based on formulas and plugging in measurements when you have a scale in the room. The same thing applies to grading light behavior. I think the well trained minds at the major labs know that direct measurement is the right methodology. They went down a poorly chosen path and are very hesitant to go back and take a new look at direct measurement technology. It would look like they wasted a lot of money, and time. In the end, I''d "predict" they will cut their losses, go back, and adopt direct measurement of light behavior instead of making predictions. This may be why Helium has not been fully appreciated by the major labs. It works superbly for measuring and as an aid to cutters. I doubt it will be the machine to grade light performance, although it may well do a very decent job with round diamond prediction.

Predictions are superb for cutters to design and plan with. Predictions fail to be as precise and repeatable as direct measurement.

Direct measurement does not care how many chevron facets there are. The look of the diamond may be very different with different facet arrangements. It is up to the dealer, the retailer and the consumer to vote which they prefer. We don''t need people to agree. TO each their own choice. A direct measure of light behavior will make comparison of perfomance easier to describe. No one will be forced into choosing what they don''t prefer regardless of how the grade is gathered.

 

[He Scores]

RE: Ever heard of Not Invented Here syndrome?


I EXPERIENCED it. From every lab to which I pitched BrayScore.


Bill Bray
Diamond Cutter

"....because looks can be decieving"

 

[Cehrabehra]

Date: 11/13/2006 1:43:30 AM
Author: Garry H (Cut Nut)

Date: 11/13/2006 1:12:52 AM
Author: Cehrabehra

most, huh??? if the helium works so well, why the heck NOT make it a standard?


if technology isn''t ready to provide these on every cert, why the heck not push for it? that''s my vote!

Ever heard of Not Invented Here syndrome?

Sergey is Russian

helium has fast become the new standard in india where Russian''s are not seen as threatening.

The main US labs we discuss here have 1 or 2 Helium Polished.

AGS use their Helium when the model builds are not good enough for their 3D scanning software, but a little bad scan here or there does not worry them - but the scans would rarely be good enough for printing on reports.

Helium takes a little longer to run a scan, and that is the main reason the labs give, as well as they already own the other scanners.

well that totally blows!! the best man should win *regardless* of what country he''s from! I hope he can work out the kinks to get his product standardized if it truly is all you think it is!

 

[Cehrabehra]

Date: 11/13/2006 7:34:58 AM
Author: He Scores
RE: Ever heard of Not Invented Here syndrome?


I EXPERIENCED it. From every lab to which I pitched BrayScore.


Bill Bray
Diamond Cutter

''....because looks can be decieving''

so it''s not just a country thing, it''s a lab thing? RIDICULOUS!!!

 

[Serg]

Cehrabehra,

We have conflict of interests with all labs.

Some Our goals: Decreasing commoditization diamond market, impart some fashion to cuts
Our Instruments:
1) Same rules for ALL cuts.
2) Objective grade
3) CAD system for developing new cuts
4) Standardization of light condition, etceteras

Some Labs goals: Conservatism on diamond market, less risk, less expenses

 

[Garry H (Cut Nut)]

Date: 11/13/2006 12:21:41 PM
Author: Serg

Cehrabehra,

We have conflict of interests with all labs.


Some Our goals: Decreasing commoditization diamond market, impart some fashion to cuts
Our Instruments: Labs can not grade the cut quality of any new cuts. Most will not even call them by their legal names.
1) Same rules for ALL cuts. For example a princess that has 90% of the light return of a symmetrical cut Tolkowsky round will be given 90% for light return. But if someone develops a new cut that has 2% more light return than Tolk round - it will be graded accordingly.
2) Objective grade The stone would get the same grade every time based on its physical attributes, and not on some opinion of a grader.
3) CAD system for developing new cuts Sergey will soon begin to release a family of products and services for the development of new and we believe potentially better cuts than those that have now commoditized the market 9rounds 45% and princess 25% = about 2/3rds of the market reducing consumer interest and choice as well as leading to a commoditized market.
4) Standardization of light condition, etceteras For example a diamond measured on any of the 3 currently available direct measurement devices will get different grades from all 3 devices. Each company will argue that their device is most accurate. We will conduct testing and studies that can result in industry wide standardization. We will do a much better job than GIA did.


Some Labs goals: Conservatism on diamond market, less risk, less expenses

 

[Paul-Antwerp]

Date: 11/13/2006 12:21:41 PM
Author: Serg

Cehrabehra,

We have conflict of interests with all labs.
Some Our goals: Decreasing commoditization diamond market, impart some fashion to cuts
Our Instruments:
1) Same rules for ALL cuts.
2) Objective grade
3) CAD system for developing new cuts
4) Standardization of light condition, etceteras

Some Labs goals: Conservatism on diamond market, less risk, less expenses

You know, not a week goes by and someone is calling us or visiting our office, in order to offer us the services of another, even cheaper and more efficient telephone operator. This can all be true, but I am never tempted to take them up on their offer.

In such case, I would not like it at all, if any of these suppliers would openly call me inefficient, and say that we are boycotting them because we support some kind of conservatism, and we want to oppose progress.

I have my reasons not to buy a product or an offer, and it is the supplier''s duty to make his offer so good that I cannot refuse it.

Live long,

 

[Serg]

Paul,

Lets separate the conservatism in choice of service from conservatism in new choice of new technology.
( Just silly example) One case if you do not see reason to change phone operator, other situation if you do not like use Internet.

Of course conservatism is important part any business if other parts are present too.

BTW I am not doing any suggestions to Labs. HRD lesson was enough for me, more or less I am understanding goals and possibility of labs now. We can not win in service on current market, we will try to change the diamond market .

 

[Garry H (Cut Nut)]

It is a good analogy Paul.

Unless the new player in a consrvative market gives people a better value / benefit proposition, few will accept the ''new'' offers. Take Skype for instance. Because it is free and the people who I often talk to are a long way away (like Leonid) it saves me a lot of $$$. But it is also more convenient for me to talk to Leonid by Skype.

Yet my friend Michael, who I ride with on Sunday - I always call his cell phone by Cell phone. But he is more often in Tokyo or Bombay when he answers, so it costs me a fortune (he works for IBM and owns a seat on planes). But I do not think to call peoples cell phones or land lines on Skype unless I am overseas.

So I agree Paul - there is a natural resistance.
Even with the 0014 service here in Australia - that costs 1/4 of the regular 0011 international service - it only requires you dial 0014 rather than 0011, and the lines are the same or better. Hardly anyone knows about it - yet there is no account to set up - no effort, just change one # when you dial - but do you think I can get my staff or family to use it?????????????

Date: 11/14/2006 5:43:20 AM
Author: Serg
Paul,

BTW I am not doing any suggestions to Labs. HRD lesson was enough for me, more or less I am understanding goals and possibility of labs now. We can not win in service on current market, we will try to change the diamond market .

But think now about what Sergey is saying.
Dave / Imagem and Gemex bscope would like labs to integrate their services into regular lab biz.

Sergey is over that. Pushing water up-hill.

We need a new paradigm for this industry.

 

[Garry H (Cut Nut)]

Date: 11/14/2006 4:40:22 AM
Author: Paul-Antwerp

I have my reasons not to buy a product or an offer, and it is the supplier''s duty to make his offer so good that I cannot refuse it.

Live long,

http://www.elmyrservices.net/stonepreviewtwo.php?id=ab28b30682728edaa2387506a61e711c&cid=2

I understand why you would proudly use the service offered in Antwerp by Emylr. But I wonder how many Antwerpen diamantaires are using this reporting service that you have championed?

They offer an alternative of sorts (to plug some gaps) to traditional telephone / lab services

 

[Cehrabehra]

Date: 11/14/2006 6:01:15 AM
Author: Garry H (Cut Nut)
Sergey is over that. Pushing water up-hill.

We need a new paradigm for this industry.

True innovation is a wonderful thing and yet can be met with the greatest of resistance from tradition, convention, and those who have a vested stake to promote their product, however lesser.

I hope this new paradigm embraces the whole flavor thing we''ve been discussing.

 

[Garry H (Cut Nut)]

Date: 11/14/2006 10:42:13 AM
Author: Cehrabehra

Date: 11/14/2006 6:01:15 AM
Author: Garry H (Cut Nut)
Sergey is over that. Pushing water up-hill.

We need a new paradigm for this industry.

True innovation is a wonderful thing and yet can be met with the greatest of resistance from tradition, convention, and those who have a vested stake to promote their product, however lesser.

I hope this new paradigm embraces the whole flavor thing we''ve been discussing.

I expect so Cehrabehra

Even to the extent that diamond cuts that look best under night lighting, and others for daytime only will be predictable.

There should be as many flavors as there are people with creativity to produce them.

Shoes and hand bag industries should loose some cache'' once we get this party on the road!

 

[Garry H (Cut Nut)]

And back on topic - it should be possible to grade each of many attributes of any diamond, so if you wanted and liked pinfire from 4 chevron princess, then you should be able to select diamonds with those attributes - even factors like crushed ice appearance should be predicatable.

And cutters could then produce the best chevron option for a given ct wt - crown and pavilion / table combination.