Am I an ideal fanatic?

[dymonite]

It seems that the general concensus on this forum is that cut rises above all other diamond criteria in determining the ultimate brilliance of a stone. On the other handr, although making a slight sacrifice in colour and clarity usually have miniminal significane - can you make similar minor sacrifices in cut?

It is possible to make minor sacrifices in cut without diminishing a noticeable brilliance of the stone?

How close do you need be close the maximal light return e.g. defined by diamcalc for people to notice a discernible difference with the naked eye.

Is it as much futile to search for maximal light return in a diamond as to demand that the diamond be colourless and flawless before you are satisfied that you have a good looking stone.

Can better colours i.e. E versus G can compensate for slight reductions in light return from a stone?

 

[Richard Sherwood]

Good post, dymo.

One of my observations in reading posts from the "ideal cut" advocates, is that they seem to have become lop-sided. They have taken just one of the four C's, and elevated it to God-like status.

I always have considered myself a "cut connoisseur". And truthfully speaking, I have seen thousands of diamonds with "fair", or "fair to good" cuts which are positively pleasing.

If you were to follow the logic of the "ideal cut" advocates, these diamonds should be shunned, avoided, and never purchased.

As a good friend of mine says, "Bulloney". Cut is just one aspect of a diamond in the consideration of it's purchase, and it is to be balanced just like the other 3 C's in considering the ultimate purchase.

This is not to detract from the argument for the "better" cut, just as I would not attempt to detract for the argument of a "better" color. Rather, it is an attempt to bring balance into the picture. I have seen plenty of gorgeous "K" color diamonds. I have seen plenty of gorgeous "I1" diamonds. And I have seen plenty of gorgeous "sub Ideal" cut diamonds.

Rich, GG
Sarasota Gemological Laboratory

 

[Garry H (Cut Nut)]

Rich I notice that you seem to be locked into the idea that AGS type gradings that are based on tolerances arbitrarily applied to Tolkowsky cut parameters define cut quality.

Many people have poohoo'd cut quality because such systems* do not adequately account for some very nice looking stones with say AGS3 and AGS5 ratings.

If you want to wade through all the MSU and my website stuff you can find out heaps. But probably the best place to start is with Jasper Paulsen, who wrote an excellent review of Tolkowsky.

http://www.folds.net/diamond_design/index.html#ed_note_02

You can actually read the whole original 1919 book there, as well as find out where mr T made a few mistakes. But most importantly you will find that the inverse proportion between crown and pavilion angles that I discovered with the ideal-scope, and MSU quantified in 1999, has been hidden in Tolkowsky's approach all these years.

* Even my good freind Dave's AGA system falls foul on this basis although it still works well because it is very tight.

 

[Richard Sherwood]

Garry, I've already waded through your site, MSU's, and the Paulsen Tolkowski critique. More than once.

There is very little there I disagree with. It is cutting edge technology. I've known instinctively for decades that there are beautiful cuts which do not fall within the accepted "norms" of the industry. I trusted my eyes more than their numbers. That is the same thing you are accomplishing with your IdealScope. I applaud you for your efforts to elevate the cutting standards of the industry.

Here is where I disagree with you. Your tolerance for "non ideal" (using your IdealScope as a barometer) cuts is very low. These cuts quickly degenerate into "bad" or "reject" cuts in your eyes, when in the eyes of others (the majority of consumers & the industry) they would still be considered "good" or "fair to good" or "fair" cuts.

It reminds me of color connoisseurs who advise people to buy nothing below a "G". Or clarity connoisseurs who advise people to buy nothing below a "VS2".

I feel that if your IdealScope rating system were more realistic in how it deals with "sub Ideal" cuts, it would catch on more easily within the industry and the public. As it is now, you're suggesting that 90+% of the diamonds which are worn and enjoyed everyday are "bad" cuts. Try telling that to a woman who has enjoyed the beauty of her stone for twenty years, and received numerous comments on the beauty of it. She's just not going to swallow it.

The word "bad" is what I'm objecting to. It is too strong a term. Not "excellent" maybe, or "very good" even. But still brilliant enough to be a "good" cut, or "fair to good", or "fair" cut. Do you see what I mean? I don't mind the line you've drawn on the sand, I only object to the terminology you're using to describe those on the other side of the line.

Rich

By the way, is this your website? If so, is it still okay to bash you?

 

[Garry H (Cut Nut)]

Hell Rich it is always OK to bash me - where ever I am

It is Leonids site, but I have a bit to do with it.
we have been good mates for a couple of years (mates in the Aussie context = friends, nothing more).

Your comments are fair and fine.
I do believe that the people selling average cut quality are selling 'lousy cut quality' and that is only because there is no way of knowing any better. I want to reduce the +50% of lousy stones to <25% and raise the overall standard.

We are well on the way to providing cutters with a revolutionary new method to know what they are going to cut when they plan the rough. They will know what th stone will look like and even be able to see a virtual ideal-scope.

This will be a real revolution and we should be able to publicise it by Tucson early in the new year.

Mark my words - this crusade is going to hot up

But do not worry - I am a realist not a perfectionist. Super ideal cuts make up about 3% of the market, and will be unlikely to ever be more than 10%. What I call bad is more than 70-80% and what I sell is only sometimes super ideal cut - just the top 10%.

 

[dymonite]

Not trying to be confrontational but only to satisfy my mind; I had an interesting discussion with a ring manufacturer about the merits of ideal cut.

He seemed a honest and upfront sort of guy and was happy to accomodate any of my whims and wishes in choosing a stone. There was never any pressure on me in making any hasty decisions. On the other hand,he clearly had ideas at variance with the HCA regarding choosing a good diamond. Nevertheless, he is allowing me to make my own conclusions and use whatever methods I wanted to choose a diamond.

He contended the following:

1) The GIA is in cahoots with DeBeers and any research on brilliance has to be seriously questioned due to possible bias

2) Colour is a greater determinant of brilliance than cut

3) Most people in the business can see if a diamond is of superior quality without resorting to unusual scopes, proportion measurements etc

4) The ideal cut mob are trying to press an agenda which is not shared by many

He also said that the perfectly cut diamond can actually reflect back 100% of the light that enters it - this did seem a bit weird to me. Is this possible?

Having said this he admits never seeing or using the ideal scope.

My spin on this is that

1) he is not trying to con me but just ignorant of the importance of perfect cut versus good/very good cut

2) since he deals mainly with the good/very good cuts (perfect cuts being very rare) that colour is the final determinant of how good the stone looks. Never seen a perfect diamond, he is not aware of how much difference it can make

I know I have lots of questions but what is everyones take on this?

 

[Garry H (Cut Nut)]

ignoraance is bliss

 

[pricescope]

Well said Garry.

I like this one the most:


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2) Colour is a greater determinant of brilliance than cut
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3) Most people in the business can see if a diamond is of superior quality without resorting to unusual scopes, proportion measurements etc.
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As Garry already pointed out most of the people in the industry look at the loose diamonds against the light source i.e. light leaking diamonds look good.


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He also said that the perfectly cut diamond can actually reflect back 100% of the light that enters it - this did seem a bit weird to me. Is this possible?
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No it is not possible. There are plenty of light rays that escape from the back of any diamond even the most ideal one

You have to look at ideal cut stones yourself to make your mind. The easiest way may be to find Herts on Fire dealer in your area.

 

[dymonite]

When he asks a customer to evaluate it, it doesn't advocate backlighting it with a source. His methods:

1) To assess brilliance - place the several stones on a piece of white paper, take it outside into daylight, rock the diamonds around and look forr the brightest stone

2) To assess fire - take the stone outside once again, look for dispersion thrown as rainbows unto your shirt

3) To assess clarity - back light it intensely with a white light and examine with a loupe.

Is this how the experts 'eyeball' the diamond when making a final assessment of appearance. What was done to validate the results generated by research? What should I do to confirm my ideal-scope impression of a good stone?

 

[bingbongbug]

I am admittedly just an avid novice, but I think I hear Garry and Richard saying the same thing, but in different ways.

Richard says that most people get stones that they love, and they think they are beautiful, and therefore the average stone is not bad, but merely fair, or average. In other words, if most people have stones of this quality, and find them quite beautiful, how could they be bad?

Garry, on the other hand, says that the bar is low in diamond cutting because the bar is low in what people know about diamonds. E.G. because people don't know any better, they pick these stones, creating the demand for sub-par stones, which, in a recursive loop, causes diamond cutters to cut more sub-par stones and flood the market with them such that people don't know any better than to buy these common examples of diamonds because it's what they know. In essence, raising the bar, with both education and higher industry standards, results in the demand for the better-cut stones.

Which to me, sounds like basically the same wavelength, but using different terms in regard to those people who are ignorantly blissful about diamonds.

At least, that's what I divine from it. I could always be wrong.

 

[Garry H (Cut Nut)]

Sit a leaking diamond on white paper in sunlight to assess cut quality????

Is this a serious and sober person?

Sorry but I have no time to reply to inept and silly comments.

 

[dymonite]

Cut nut,

With respect, but you didn't answer the question:

In what conditions should you 'eyeball' the diamond for quality?

 

[dymonite]

Ahh,

Another question that really was not satisfactorily answered re the influence of colour:

Take two stones with perfect ideal cuts.

What degree of colour difference will be required to have a noticeable change in brilliance/brightness when the diamond is mounted.

D to E,F,G,H,I?

How important is the premium for colour worth for the effect on appearance?

 

[pricescope]

Dymonite,

Let me translate


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Sit a leaking diamond on white paper in sunlight to assess cut quality????
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Having diamond on the white paper in sunlight is almost the same as viewing it against the light from behind.

The problem is that poor cut diamonds leek light in all directions and you will see a lot of light reflected from the white paper.

Now imagine a diamond set in the ring. There is no white paper or any light source under neath. Poor cut diamond will be dark and dull.

Well cut diamonds will reflect more light from the top back to your eyes no mater how you illuminate them from behind.

Idealscope is a simple tool that visualise this effect. It shows how well diamonds reflect the light from the top (pink areas) and not allows it to escape down to pavilion (white areas).

What could be done is to view the diamonds on a BLACK paper or between the fingers (like in the picture below) to block the light coming from pavilion.

 

[dymonite]

Leonid,

Thanks for the responser. A neat logical one that confirmed my impression. Therefore should I examine all diamonds between my fingers or on a black piece of paper?

How about his other idea - rainbows reflected onto an object?

 

[dymonite]

Hopefully, a less silly and inept question:

On one hand, we have Mr. Holloway et al who contend that the best way to achieve brilliance is to have either an optimal ideal-scope image or produce cut proportions which produce a high light return (according to DiamCalc computer calculations)

On the other hand, we have (presumably) respectable and sincere people in the diamond trade who continually deal with diamonds (loose, mounted and worn in everyday jewelry), that believe that they are confidently selling quality gems.

Exhaustive experiments have been performed regarding the effect of cut on light return but it seems the argument hinges on the following:

Does brilliance = no light leakage = high light return?

Although the latter two components may be synonymous, is that the same as brilliance? If we cannot prove this relationship, then doesn't this diminish the concept of light return as a major determinant of brilliance and therefore all instruments used to measure this - such as the ideal scope and the DiamCalc?

Even Mr. Holloway contends that brilliance is actually quite a subjective term. I quote him, 'One of the most complex problems that dogs me is the relationship between light return and scintillation. I am quite prepared to consider that there is no way to measure brilliance. Light return is a quantifiable thing, but brilliance is a human variable.' He also illustrates how contrast can alter the perception of brightness (which will also influence scintillation). Perhaps it is the most 'pleasing'/optimal scattering of bright components which gives a diamond the appearance of brightness? Perhaps total light intensity returning back to the viewer (as expressed as high light return or absence of light leakage) makes only a moderate contribution to this perception?

The whole definition of brilliance has revolved around a rather abstractl mathematical concept called weighted light return (WLR) defined by the GIA. I was wondering how extensive human physiological experiments have been to validate this measurement. The GIA admits that exhaustive human examination of their 'virtual' diamonds was not conducted. They claim that small WLR differences could be detected under 'controlled observation environments and lighting conditions' or by trained viewers. Does this mean that WLR differences are not as easily detectable by most people under everyday conditions? How well will people be able to discern these differences such as under full daylight, an overcast day, in a room with normal illumination or an office building with fluorescent lights?

Mr. Holloway says that his customers prefer diamonds with low light leakage (compared to what? - ones with terrible leakage). Not being overtly critical, is this not just anecdotal (most clients say any diamond is beautiful). Has anyone attempted a blinded randomized control trial to examine this? How about a simultaneous Coca-cola taste test on 50 untrained volunteers?

My questions obviously come without a comprehensive appreciation of the literature that is out there. However, I would think that they would be valid concerns. Any thoughtful responses out there would be appreciated.

 

[Garry H (Cut Nut)]

D I appreciate your enquiring mind, but I simply do not have the time to answer all your questions - particularly if they include a debate with an unkown diamond dealer.

There are various groups, including MSU and myself who are conducting those experiments. In addition I teach trade people to do what you are talking about, and the level of knowledge among the trade is appalling.

No light return and a lot of leakage gives a bad result - especially when the diamond is dirty = most of the time.

i am not God, but I am obsessed with answers to the questions you pose.

I never sell dimaonds below H color - the first and I believe the only Australian jeweller to make such a stand.

Keep reading and you will answer your own questions