Is leakage the

[spicytuna]

[/quote]

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don''t get that by now there is no sense even talking to you because that is diamond 101 and if you don''t understand that simple concept by now it is a waste of time even talking to you.

To much obstruction is an issue also.


[/quote]


Wow...all of us "regular folk" should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don''t you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn''t realize that we were wasting the experts'' time.

 

[princesss]

Date: 4/9/2010 12:28:25 PM
Author: spicytuna

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don't get that by now there is no sense even talking to you because that is diamond 101 and if you don't understand that simple concept by now it is a waste of time even talking to you.

To much obstruction is an issue also.


[/quote]


Wow...all of us 'regular folk' should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don't you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn't realize that we were wasting the experts' time.

[/quote]
Trust me, that wasn't directed at any newbie - RD and Strm (aka Karl) have been going back and forth for ages about this. Karl isn't making a sweeping statement that he won't speak to anybody that doesn't understand that, but that if, after explaining it to RD many, many times RD still seems to miss the point, then it's not worth continuing to beat his head against the wall in order to explain it when he knows he will be ignored.

 

[Demon]

Date: 4/9/2010 12:21:24 PM
Author: kenny
Recently anti-intellectualism and anti-science sentiment is growing.
Many want a return to simpler times when things weren''t so darned complicated and it was okay to just go with your gut.
Many folks are suspicious of smart people, especially if they are leaders.

It is no surprise to me we see a clash between these two kinds of people in a discussion of diamond cut.
It also does not surprise me a vendor would work so hard to endear himself to this group of people.

I want to make it clear that I am not disputing the tools for detecting leakage, or that leakage exists and is a bad thing. I''m just curious as to how much leakage it takes before the human eye can detect it.

 

[kenny]

Demon this is not directed at you.
It is a response to a trend I see over a long period of time.

 

[stone-cold11]

Date: 4/9/2010 12:28:25 PM
Author: spicytuna

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don''t get that by now there is no sense even talking to you because that is diamond 101 and if you don''t understand that simple concept by now it is a waste of time even talking to you.

To much obstruction is an issue also.

[/quote]

Wow...all of us ''regular folk'' should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don''t you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn''t realize that we were wasting the experts'' time.
[/quote]
Karl is referring to RD, who has been asking the same questions, using different inferences and terms, for the last year or so, yet refusing to learn the terminology that almost everyone else is talking in. If you want to discuss something, set down the terminology so that everyone is on the same page. RD has been moving that around, confusing new comers like you by mixing up what each terms meant.

 

[kenny]

Date: 4/9/2010 12:40:16 PM
Author: Stone-cold11

Date: 4/9/2010 12:28:25 PM

Author: spicytuna

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don't get that by now there is no sense even talking to you because that is diamond 101 and if you don't understand that simple concept by now it is a waste of time even talking to you.


To much obstruction is an issue also.

Wow...all of us 'regular folk' should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don't you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn't realize that we were wasting the experts' time.

[/quote]

Karl is referring to RD, who has been asking the same questions, using different inferences and terms, for the last year or so, yet refusing to learn the terminology that almost everyone else is talking in. If you want to discuss something, set down the terminology so that everyone is on the same page. RD has been moving that around, confusing new comers like you by mixing up what each terms meant.[/quote]

Helloooo.
If he "got it" and ended the discussion he couldn't keep posting with the link to his website in his sig line.
Wake up and smell the coffee.

 

[spicytuna]

Date: 4/9/2010 12:37:09 PM
Author: Demon

Date: 4/9/2010 12:21:24 PM

Author: kenny

I want to make it clear that I am not disputing the tools for detecting leakage, or that leakage exists and is a bad thing. I''m just curious as to how much leakage it takes before the human eye can detect it.

I think that just depends on the visual acuity of the person viewing the diamond.

 

[Rockdiamond]

Date: 4/9/2010 11:51:32 AM
Author: risingsun
Everyone is entitled to like what they like and buy what they choose. The point, for me, is that I want to know all I can about the diamond I am choosing and the reasons the stone performs as it does. I realize that this is not important to everyone, but it is for me and many others who are PS members. This is an educational site. All points of view are presented. I think it is an exercise in futility to dispute methods of evaluation that have scientific valildity and reliability.* That doesn''t prevent anyone from choosing the diamond that speaks to them. It is about making an informed choice.


To Stone: I aced my graduate school courses in research, design and statistics, but I never had occasion to use your formula. I am planning to wear a big ''L,'' for loser, across my forehead for the rest of the day

If you have ever watched Top Gear, this is the preferred method of shame!!


*In case anyone wants verification of this statement, I defer and refer them to Brian, Paul, Todd, Storm, Jon, Wink, Garry, and Stone [knowledge in optics] and the AGS, who uses the ASET as part of their grading parameters. Sorry if I''ve left any of the experts out. It was an oversight.

Education is a wonderful thing- learning new things expands our minds and horizons.
Taking a little bit of knowledge which is then used to to warn people needlessly can be exactly the opposite.
Back to my analogy- that Buick has a lot of oxygen in there- be careful.
That''s why I chose the "boogeyman"
When we''re little kids, we can easily be led astray to fear things without cause.
Does that happen regarding leakage?''

Does the word "performance" used in describing a diamond have the same effect?
Can this cause readers to assume that a stone declared "a better performer" is automatically going to appeal to them more than another which is declared a "lesser performer".
If someone looks at both, and finds the lesser "performer" is more appealing, would they then be accused of loving badly cut diamonds?

Can light "perform"?

 

[Karl_K]

Date: 4/9/2010 12:40:16 PM
Author: Stone-cold11

Date: 4/9/2010 12:28:25 PM

Author: spicytuna

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don''t get that by now there is no sense even talking to you because that is diamond 101 and if you don''t understand that simple concept by now it is a waste of time even talking to you.


To much obstruction is an issue also.

Wow...all of us ''regular folk'' should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don''t you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn''t realize that we were wasting the experts'' time.

[/quote]

Karl is referring to RD, who has been asking the same questions, using different inferences and terms, for the last year or so, yet refusing to learn the terminology that almost everyone else is talking in. If you want to discuss something, set down the terminology so that everyone is on the same page. RD has been moving that around, confusing new comers like you by mixing up what each terms meant.[/quote]

That is correct I was talking to David only.
10s of thousands of people have got these concepts over the years so it is obvious he is just playing dumb to confuse people.

 

[stone-cold11]

Date: 4/9/2010 12:11:29 PM
Author: ericad
I get David''s point about the term ''leakage'' being a word that conjures up a negative image but that some leakage doesn''t always equate to an unattractive diamond - it''s a case of ''it depends''. Seems to me that when educating buyers, we might say that some leakage may be tolerable to many buyers, the degree of how much is ''allowable'' is complex and depends on the buyer''s personal preferences, budget considerations, etc. and that one would caution buyers that leakage follows a continuum, the extreme end of which results in windowing. Just like the extreme end of obstruction results in a dark diamond with little contrast or brightness, but that doesn''t mean that all obstruction is bad and to be avoided.

Yes, it is a continuum, leakage and obstruction depending on the extent. But how does someone, who coming here asking for help generally means he/she knows almost nothing about diamonds, does not see many diamonds, knows what to look for, what is obstruction and what is leakage, what jewelry lighting and other lightings effect have on these optical artifacts and what he prefers?

Generally stones with leakage will be stones that are cut with steeper pavilion than ''ideal cut'', heavier stones with less light returns, while stones with leakage will be with shallower pavilion, lighter stone. We generally advice against both, especially for rounds as there are so many that are cut without these 2 ''problems''. If you know what you want, with regards to obstruction and leakages, then choose what you want why would you care or ask for others'' opinions?

 

[Karl_K]

Date: 4/9/2010 12:11:29 PM
Author: ericad
Quick question: is 'windowing' be a term that could be used interchangeably with 'leakage'? That's what I think of when I think of extreme cases of leakage - seeing through the stone to whatever is below it from the face up position because the light isn't being reflected anywhere - glassiness. The leaky spots are not lively when viewing the diamond face up, even when the stone is in motion, and you can see the difference between the windowed areas and the other areas within the stone. Then I sort of think of it on a continuum - extreme cases of windowing that the majority of people would find unattractive versus more mild leakage where it may or may not be obvious to the eye and can become a matter of preference and overall look and personality of a stone.


In old cuts, I think a large culet is a good example of leakage that isn't considered detrimental to the beauty of the diamond, but I've also seen examples of old cuts with lots of eye-visible leakage/windowing under the table, though it's not common.


This differs from obstruction, very common in old cuts, where the light is blocked by the viewer and the obstructed areas become the contrasting patterns you see in the stone, and can be very pleasing to the eye, particularly when the stone is in motion and the areas of dark and light keep changing resulting in lots of life and interesting light play. But, as with leakage, too much obstruction can be unattractive, it follows a continuum and is subjective based on the preferences of the buyer.


I get David's point about the term 'leakage' being a word that conjures up a negative image but that some leakage doesn't always equate to an unattractive diamond - it's a case of 'it depends'. Seems to me that when educating buyers, we might say that some leakage may be tolerable to many buyers, the degree of how much is 'allowable' is complex and depends on the buyer's personal preferences, budget considerations, etc. and that one would caution buyers that leakage follows a continuum, the extreme end of which results in windowing. Just like the extreme end of obstruction results in a dark diamond with little contrast or brightness, but that doesn't mean that all obstruction is bad and to be avoided.


Am I thinking of these things correctly? Dealing in old cuts, I don't spend a lot of time thinking about ASET, HCA, IS, leakage, etc. because they aren't relevant to antiques, but the above is my amateur way of articulating what I have absorbed via osmosis, lol, from my years on PS. Please correct me if I'm wrong!

While windowing is a lot of leakage it is a gemstone term that refers to effects of the low RI of gemstones.
The higher RI of diamonds makes some of the parts of the definition of windowing not applicable.
It is better I think to keep it separate to not create more confusion which is why the term leakage is used instead.

 

[Rockdiamond]

This is NOT a one year old debate- it goes much further back than that.

Stone- the other day you accused me of not being able to use simple equations to mislead a consumer...I mean to figure out the volume of a diamond- which you totally failed to do anyway.
Is this like that?

Karl- I would like to frame this in a way that may make more sense to you.
We are at opposite ends of the spectrum in many ways.
Has it ever occurred to you that the debate between us educates many readers?
Take the page written by John Pollard, which I linked to in the opening post. Is it possible that my continually questioning the assumptions about leakage were part of the motivation for his writing that page?

Karl, it''s true, we started on a bad foot.
I am surely responsible for a good part of that.
But isn''t it time to start respecting each other for the work we do?

You have names for a lot of things I find are intuitive for people.
Yet, in your work designing diamonds it''s possible those names take on a different importance.

Isn''t it also possible that people can judge the cut of diamonds without knowing the difference between what you describe leakage and obstruction?
Wouldn''t they know from looking at the diamond which is a pattern, and which is a window?
If leakage as described in GIA EX cut grade stones is a problem, wouldn''t that be possible to depict in photos?

 

[Demon]

Date: 4/9/2010 12:44:45 PM
Author: spicytuna

Date: 4/9/2010 12:37:09 PM
Author: Demon

Date: 4/9/2010 12:21:24 PM

Author: kenny

I want to make it clear that I am not disputing the tools for detecting leakage, or that leakage exists and is a bad thing. I''m just curious as to how much leakage it takes before the human eye can detect it.

I think that just depends on the visual acuity of the person viewing the diamond.

And that''s why I was asking about the ''average'' naked eye.

 

[Karl_K]

Date: 4/9/2010 10:42:38 AM
Author: Demon
There''s something I''ve been wondering about for a while now.....at what point does leakage become detectable to the average (if there is such a thing) naked eye?

Depends on the person the diamond and the setting and how clean the diamond is and where the leakage is.
Some people can see more detail in diamonds light return than others.
A high setting can allow light to enter the diamond from the back and cover some leakage but add a little dirt and it is right back there.
A classic bezel or any other setting that blocks light to the pavilion will make it stand out more.
Under the table leakage in an RB is more visible to more people than leakage elsewhere.
More than normal leakage around the edge can make the diamond look smaller but within reason to most people not make it look dark.

Leaving old cuts out of the discussion and only talking about modern RB diamonds.
When it is very simple to avoid the issue by getting diamonds that don''t over leak and are overall brighter then why bother with them?
Some people don''t care, some people want to save money.
Others want the highest balanced light return most beautiful diamond they can for their money.
Diamond beauty is not any one thing it is a balance of many things.
Which leaves room for people to create confusion and trouble for their own gain for people who want to learn about how and why diamonds work.

 

[ChunkyCushionLover]

Your initial post and title is funny RD, good sense of humour.

On a more serious note,

In ~30+ years in the diamond business do you still claim you have never seen a round diamond with a lifeless ring where no light is returned around the edge of the table?

Forget getting hung up with photographs, ASET, Crown Angles, Pavillion angles, this thread appeals to those who don't embrace the technical tools or want to understand diamond proportions and how they translate to real world performance.

How can you be leading a discussion on colorless diamonds and leakage when in real life you acknolwedge you haven't seen this lack of liife appearance?
Have you ever used Karl's red paper or red cloth underneath pavillion test on loose diamonds to look at your own inventory and see more clearly where the leakage is?

I've seen maybe a few hundred 1ct and above round diamonds up close in my lifetime and I can easily spot stones with leakage at the edge of the table when viewing away from the bright jewelry store lights.
My wife has a cushion cut with a modern round brilliant style of pavillion and I see a fair sized ring on the outside of the table which is never dark, it just doesn't show brightness or fire in any lighting or any tilt angle.
The pictures of her ring are in the SMTR thread and you won't see some glaring ring of death in those photographs either, it doesn't mean we can't see the areas where it performs poorly in real life especially in low light conditions.

Ignorance is bliss RD, especially for the "trust your eyes" types and boy do you play up the ignorance of the novice posters. A consumer can very easily if not shown the comparison between an "ideal" and one with moderate to severe leakage choose a larger or less expensive per carat stone just by the stats on paper, a photograph, and then a limited viewing of a small number of non ideal stones in person. That is NOT an informed decision by any stretch of the imagination.

For those who really care about the cut of diamonds the PS community often advocates making thorough comparisons and then making an informed decision. I don't feel we need to remind the consumer that Superideals cost more, that part is pretty obvious, but pretending that all modern RB are equally beautiful and advocating ignoring the flaws of diamonds like leakage as trivial is simply wrong.

Expressing concern over leakage highlights the fact that there are diamonds in the same cutting style that have better light return and the customer should be aware of this and then make their own subjective judgement on what they feel is most important.

 

[Demon]

Date: 4/9/2010 1:11:36 PM
Author: Karl_K

Date: 4/9/2010 10:42:38 AM
Author: Demon
There''s something I''ve been wondering about for a while now.....at what point does leakage become detectable to the average (if there is such a thing) naked eye?

Depends on the person the diamond and the setting and how clean the diamond is and where the leakage is.
Some people can see more detail in diamonds light return than others.
A high setting can allow light to enter the diamond from the back and cover some leakage but add a little dirt and it is right back there.
A classic bezel or any other setting that blocks light to the pavilion will make it stand out more.
Under the table leakage in an RB is more visible to more people than leakage elsewhere.
More than normal leakage around the edge can make the diamond look smaller but within reason to most people not make it look dark.

Leaving old cuts out of the discussion and only talking about modern RB diamonds.
When it is very simple to avoid the issue by getting diamonds that don''t over leak and are overall brighter then why bother with them?
Some people don''t care, some people want to save money.
Others want the highest balanced light return most beautiful diamond they can for their money.
Diamond beauty is not any one thing it is a balance of many things.
Which leaves room for people to create confusion and trouble for their own gain for people who want to learn about how and why diamonds work.

Thank you. I guess it''s a fairly impossible question to answer, really. I was just curious about the difference between what technology can find and what we can really see. The difference between minimal - not visible to most of us - and overly leaky. Better to be cautious, definitely.

 

[Demon]

Date: 4/9/2010 12:39:40 PM
Author: kenny
Demon this is not directed at you.
It is a response to a trend I see over a long period of time.

Cool. I was just trying to make my point clear, too.

 

[stone-cold11]

Date: 4/9/2010 1:00:04 PM
Author: Rockdiamond
Stone- the other day you accused me of not being able to use simple equations to mislead a consumer...I mean to figure out the volume of a diamond- which you totally failed to do anyway.

What do you mean I fail to figure out the volume? I already showed you the equations, if you do not understand what I am doing there it is not my fault.

 

[ChunkyCushionLover]

Date: 4/9/2010 12:32:22 PM
Author: princesss

Date: 4/9/2010 12:28:25 PM
Author: spicytuna

The arrow pattern is caused by obstruction(reflection of the viewer blocking the light) if you don''t get that by now there is no sense even talking to you because that is diamond 101 and if you don''t understand that simple concept by now it is a waste of time even talking to you.

To much obstruction is an issue also.

Wow...all of us ''regular folk'' should just pack up and go home. I have one year in Optics, 3 years of Ophthalmic Optics Graduate studies, and 10 years of experience under my belt. Granted, its not diamond optics, but I think that we all need a good refresher course every now and then...don''t you? RD brings up a lot of good questions...questions that I would like to have answered as well. That is why I am here. I didn''t realize that we were wasting the experts'' time.

[/quote]
Trust me, that wasn''t directed at any newbie - RD and Strm (aka Karl) have been going back and forth for ages about this. Karl isn''t making a sweeping statement that he won''t speak to anybody that doesn''t understand that, but that if, after explaining it to RD many, many times RD still seems to miss the point, then it''s not worth continuing to beat his head against the wall in order to explain it when he knows he will be ignored.[/quote]Astute observation Princess. The sad reality is that RD is preaching to the less informed, his focus is not what the Prosumers and trademembers reply, he is looking for anecdotal evidence from less experienced posters. A few will reply in support, and usually these posters are motivated by the need to validate their own purchase decisions. On that basis they will support RD''s opinion and can relate to the notion that making a less informed choice, ignoring flaws, and just generally assessing the overall appearance has its merits.

 

[ChunkyCushionLover]

Date: 4/9/2010 12:11:29 PM
Author: ericad
Quick question: is 'windowing' be a term that could be used interchangeably with 'leakage'? That's what I think of when I think of extreme cases of leakage - seeing through the stone to whatever is below it from the face up position because the light isn't being reflected anywhere - glassiness. The leaky spots are not lively when viewing the diamond face up, even when the stone is in motion, and you can see the difference between the windowed areas and the other areas within the stone. Then I sort of think of it on a continuum - extreme cases of windowing that the majority of people would find unattractive versus more mild leakage where it may or may not be obvious to the eye and can become a matter of preference and overall look and personality of a stone.

In old cuts, I think a large culet is a good example of leakage that isn't considered detrimental to the beauty of the diamond, but I've also seen examples of old cuts with lots of eye-visible leakage/windowing under the table, though it's not common.

This differs from obstruction, very common in old cuts, where the light is blocked by the viewer and the obstructed areas become the contrasting patterns you see in the stone, and can be very pleasing to the eye, particularly when the stone is in motion and the areas of dark and light keep changing resulting in lots of life and interesting light play. But, as with leakage, too much obstruction can be unattractive, it follows a continuum and is subjective based on the preferences of the buyer.

I get David's point about the term 'leakage' being a word that conjures up a negative image but that some leakage doesn't always equate to an unattractive diamond - it's a case of 'it depends'. Seems to me that when educating buyers, we might say that some leakage may be tolerable to many buyers, the degree of how much is 'allowable' is complex and depends on the buyer's personal preferences, budget considerations, etc. and that one would caution buyers that leakage follows a continuum, the extreme end of which results in windowing. Just like the extreme end of obstruction results in a dark diamond with little contrast or brightness, but that doesn't mean that all obstruction is bad and to be avoided.

Am I thinking of these things correctly? Dealing in old cuts, I don't spend a lot of time thinking about ASET, HCA, IS, leakage, etc. because they aren't relevant to antiques, but the above is my amateur way of articulating what I have absorbed via osmosis, lol, from my years on PS. Please correct me if I'm wrong!

Ericad your post is excellent and at a great level for this thread. Your paralell of leakage with windowing while not entirely correct as Karl K has pointed out due to differnt RIs is still a good one.
As in antiques and colored stones leakage can be partially hidden by the setting. But unlike antiques and colored stones there is no need to purchase modern RB stones with appreciable leakage under the table there are so many available without this flaw.

 

[ericad]

Date: 4/9/2010 12:53:53 PM
Author: Stone-cold11

Date: 4/9/2010 12:11:29 PM

Author: ericad

I get David''s point about the term ''leakage'' being a word that conjures up a negative image but that some leakage doesn''t always equate to an unattractive diamond - it''s a case of ''it depends''. Seems to me that when educating buyers, we might say that some leakage may be tolerable to many buyers, the degree of how much is ''allowable'' is complex and depends on the buyer''s personal preferences, budget considerations, etc. and that one would caution buyers that leakage follows a continuum, the extreme end of which results in windowing. Just like the extreme end of obstruction results in a dark diamond with little contrast or brightness, but that doesn''t mean that all obstruction is bad and to be avoided.

Yes, it is a continuum, leakage and obstruction depending on the extent. But how does someone, who coming here asking for help generally means he/she knows almost nothing about diamonds, does not see many diamonds, knows what to look for, what is obstruction and what is leakage, what jewelry lighting and other lightings effect have on these optical artifacts and what he prefers?


Generally stones with leakage will be stones that are cut with steeper pavilion than ''ideal cut'', heavier stones with less light returns, while stones with leakage will be with shallower pavilion, lighter stone. We generally advice against both, especially for rounds as there are so many that are cut without these 2 ''problems''. If you know what you want, with regards to obstruction and leakages, then choose what you want why would you care or ask for others'' opinions?

Very true, stone, it all comes down to educating the consumer, which is why he/she is on PS in the first place. The participants on PS and tools like HCA are the best resources any consumer could ask for.

 

[NJDeac]

I've read through a couple of these threads now as a previously uneducated consumer, and they seem to contain some pretty good information before they devolve into personal attacks, so thanks for keeping up the debate. With that said, it seems to me from a consumer's perspective that there's really no reason to consider diamonds that fail the HCA test, even if they receive a GIA excellent grade.

As a technical person, I appreciate the math behind the HCA. Though I've never taken any advanced classes in optics, I understand that a diamond is basically a prism with a refractive index, critical angle between the stone and the air, etc. As such, the reflective/refractive/light return performance can be reasonably estimated from the measurements of the stone. However, the open question is how great the performance delta is between a regular excellent and an "HCA approved" excellent.

Maybe HCA approved stones have less leakage and better light return, maybe they don't. I honestly don't care, because I can afford to be picky about the stones I consider.

Either GIA excellent stones that score below a 2.0 on the HCA perform better than other GIA excellent stones, or they don't. Those are the only two options. Either the "HCA approved" have less leakage, or they don't. The high HCA scoring stones are pretty much a subset of all stones that grade GIA excellent.

Here's the most important factor to this debate: there are a lot of freaking round brilliants out there on the market. De Beers isn't running out of diamond rough any time soon, and the cutters aren't going to stop cutting. As consumers, we can afford to be picky as hell, so there's no reason not to be unless you're locked in with a particular jeweler for some crazy reason.

Sure, consumers come in here for validation on their purchase and get told their stone they previously thought was perfect might have performed better with better angles. I don't see why that's a problem, though. No one is saying any stone that scores an excellent is a complete dud, just that they possibly could have done better.

I'm never going to be able to look at thousands of loose diamonds during my lifetime to learn exactly what to look for in a well-cut stone. Maybe the light return between an "average" GIA excellent and a "HCA approved" GIA excellent is 5% - I'm probably not going to be able to see that even if they were side by side. But why should I settle? There are plenty of fish in the sea, and enough of those fish have "HCA approved" angles such that I can throw back the ones that don't, even if they're great otherwise.

With the number of stones on the market, consumers should be overly picky, because they can afford to be. I don't see how anyone advising a consumer to look for stones in a narrow range of "known-good" angles is possibly doing them a disservice.

 

[oldminer]

In BMW motorcycles the factory defined many years ago the following in order of their severity when it came to oil coming out from wrong places in their motors. The least was "Weeping", the next was "Seepage" and the worst was "Leagage". The first never does more than dampen the surface of the engine case near the problem area. The second might leave a drop on your garage floor once in a blue moon, and the third is a problem which has to be dealt with. In diamonds the use of Leakage is by far an overstatement of what is taking place. Not many diamonds light up the finger under the ring from leaking light.

Diamonds of interest to us here are basically transparent. Light readily goes in and readily goes out. What passes for Leakage is often the result of light being bent, refracted, within the diamond by the density of the diamond material and the faceting pattern. Light re-focuses into more intense zones of sparkle and brilliancy and in some places the light is not going to come back to our eyes because it has been concentrated elsewhere to create the light show we expect from a diamond. The light is not "leaking" anywhere in nearly all cases, but it is being intensified in some places and lessened in other places. There was only so much light going in, a certain number of lumens, and only that amount or a bit less can come back to our eyes. Once light is intensified to look very bright in several places, there must, in turn, be places in the diamond which give beck less light and we have been often wrongly calling this leakage. Truthfully these darker zones are expected voids where light has been re-focused to return elsewhere with greater intensity. Some really thin and poorly cut diamonds act like a glass window and light does leak through, but in a finely cut diamond, I doubt we get past the BMW Weeping level.

I don't think the term "Leakage" a good one, but it does have pretty much universal usage. Now, if folks understood what it really meant, there would be less consumer doubt raised by the word itself. Leakage in the loose way it is used may have very little meaning to consumers, but it sure can scare them. It might be better to take the time to re-define what is seen in I-S and ASET images so the word is changed to something which has a better connotation.

 

[Rockdiamond]

Date: 4/9/2010 1:45:36 PM
Author: ericad

Date: 4/9/2010 12:53:53 PM

Author: Stone-cold11

Date: 4/9/2010 12:11:29 PM


Author: ericad


I get David's point about the term 'leakage' being a word that conjures up a negative image but that some leakage doesn't always equate to an unattractive diamond - it's a case of 'it depends'. Seems to me that when educating buyers, we might say that some leakage may be tolerable to many buyers, the degree of how much is 'allowable' is complex and depends on the buyer's personal preferences, budget considerations, etc. and that one would caution buyers that leakage follows a continuum, the extreme end of which results in windowing. Just like the extreme end of obstruction results in a dark diamond with little contrast or brightness, but that doesn't mean that all obstruction is bad and to be avoided.

Yes, it is a continuum, leakage and obstruction depending on the extent. But how does someone, who coming here asking for help generally means he/she knows almost nothing about diamonds, does not see many diamonds, knows what to look for, what is obstruction and what is leakage, what jewelry lighting and other lightings effect have on these optical artifacts and what he prefers?



Generally stones with leakage will be stones that are cut with steeper pavilion than 'ideal cut', heavier stones with less light returns, while stones with leakage will be with shallower pavilion, lighter stone. We generally advice against both, especially for rounds as there are so many that are cut without these 2 'problems'. If you know what you want, with regards to obstruction and leakages, then choose what you want why would you care or ask for others' opinions?

Very true, stone, it all comes down to educating the consumer, which is why he/she is on PS in the first place. The participants on PS and tools like HCA are the best resources any consumer could ask for.

I must strongly disagree Erica.
The HCA is controversial for many reasons.
One clear cut bad use is when someone loves their diamond, plugs it into HCA and suddenly finds out their eyes have been lying to them all these years.

Or, as has happened right here, consumers read one sided discussions, and decide that HCA trumps GIA.
That's a huge mistake IMO.
There is a very great possibility those same consumers might very well eliminate stones they may have preferred based on their visual characteristics.NJDeac- it's not quite a simple as you outlined- either stones "perform better or they don't. The whole issue of performance is NOT agree upon,.

I sincerely doubt that any professional in the field of diamonds would recommend trusting HCA more than GIA...maybe other than Garry..

 

[oldminer]

I do think that some, not just a few, members of the trade feel that GIA may be influenced by their largest accounts from time to time in subtle ways that create the possibility of bias or the appearance of bias in some diamond grading reports. It is not frequently proven as a fact although there was a grading scandal of limited proportions a few years ago.

The HCA, on the other hand, was produced as a free tool for consumers to use without a fee or hope for any financial gain. It did not come from someone who was going to reap much if any benefit for it and considering how long it has been in use, it has proved itself a decent tool for distant shoppers. It may not be perfect, but it is honest and objective in its results. Dealers often use deceptive tactics which the HCA cannot employ. It has good and bad features, but overall has found its niche.

 

[Rockdiamond]

Date: 4/9/2010 1:12:44 PM
Author: ChunkyCushionLover
Your initial post and title is funny RD, good sense of humour.


On a more serious note,



In ~30+ years in the diamond business do you still claim you have never seen a round diamond with a lifeless ring where no light is returned around the edge of the table?


Forget getting hung up with photographs, ASET, Crown Angles, Pavillion angles, this thread appeals to those who don''t embrace the technical tools or want to understand diamond proportions and how they translate to real world performance.


How can you be leading a discussion on colorless diamonds and leakage when in real life you acknolwedge you haven''t seen this lack of liife appearance?

Have you ever used Karl''s red paper or red cloth underneath pavillion test on loose diamonds to look at your own inventory and see more clearly where the leakage is?


I''ve seen maybe a few hundred 1ct and above round diamonds up close in my lifetime and I can easily spot stones with leakage at the edge of the table when viewing away from the bright jewelry store lights.

My wife has a cushion cut with a modern round brilliant style of pavillion and I see a fair sized ring on the outside of the table which is never dark, it just doesn''t show brightness or fire in any lighting or any tilt angle.

The pictures of her ring are in the SMTR thread and you won''t see some glaring ring of death in those photographs either, it doesn''t mean we can''t see the areas where it performs poorly in real life especially in low light conditions.


Ignorance is bliss RD, especially for the ''trust your eyes'' types and boy do you play up the ignorance of the novice posters. A consumer can very easily if not shown the comparison between an ''ideal'' and one with moderate to severe leakage choose a larger or less expensive per carat stone just by the stats on paper, a photograph, and then a limited viewing of a small number of non ideal stones in person. That is NOT an informed decision by any stretch of the imagination.


For those who really care about the cut of diamonds the PS community often advocates making thorough comparisons and then making an informed decision. I don''t feel we need to remind the consumer that Superideals cost more, that part is pretty obvious, but pretending that all modern RB are equally beautiful and advocating ignoring the flaws of diamonds like leakage as trivial is simply wrong.


Expressing concern over leakage highlights the fact that there are diamonds in the same cutting style that have better light return and the customer should be aware of this and then make their own subjective judgement on what they feel is most important.

HI ccl,
I have NEVER stated that badly cut diamonds don''t exist.
If I need a red piece of paper to see leakage, why don;t I just not use red paper under the ring?

As you mention that you easily spot leakage in stones, I again ask for photos shoing GIA EX cut grade stones, and the leakage you''re referring to.
Please re-post the photo you attached to the other thread- I think it was informative.


Oldminer- AMAZING post- spot on!!

 

[Rockdiamond]

David, we agree- many cutters and dealers don't like GIA- but I feel that's because they wanted better grades than they got. These people might even claim that larger companies get better grades. That's no my experience though....
AS a rule, are you advising consumers to trust HCA over GIA?
Do you refer to HCA on appraisals, or use it to judge value of stones?

If you do recommend the HCA to be used with more confidence that GIA cut grading, it's good to know. I respect your opinion.

Have you ever had any luck getting GIA to grade stones the way you wanted, as opposed to giving objective results? I have not.
I've seen many GIA graded stone who's color and clarity I disagreed with- yet cases where the disagreement was more than one grade have been virtually non existent in my experience.
Grading is not an exact science , which would account for the single grade difference- it's opinion.

Compare this to EGL ( particularly the non US ones) and the occurrence of two , three, even four grade differences are relatively common.

 

[clgwli]

Date: 4/9/2010 1:12:44 PM
Author: ChunkyCushionLover
Your initial post and title is funny RD, good sense of humour.

On a more serious note,

In ~30+ years in the diamond business do you still claim you have never seen a round diamond with a lifeless ring where no light is returned around the edge of the table?

Forget getting hung up with photographs, ASET, Crown Angles, Pavillion angles, this thread appeals to those who don''t embrace the technical tools or want to understand diamond proportions and how they translate to real world performance.

How can you be leading a discussion on colorless diamonds and leakage when in real life you acknolwedge you haven''t seen this lack of liife appearance?
Have you ever used Karl''s red paper or red cloth underneath pavillion test on loose diamonds to look at your own inventory and see more clearly where the leakage is?

I''ve seen maybe a few hundred 1ct and above round diamonds up close in my lifetime and I can easily spot stones with leakage at the edge of the table when viewing away from the bright jewelry store lights.
My wife has a cushion cut with a modern round brilliant style of pavillion and I see a fair sized ring on the outside of the table which is never dark, it just doesn''t show brightness or fire in any lighting or any tilt angle.
The pictures of her ring are in the SMTR thread and you won''t see some glaring ring of death in those photographs either, it doesn''t mean we can''t see the areas where it performs poorly in real life especially in low light conditions.

Ignorance is bliss RD, especially for the ''trust your eyes'' types and boy do you play up the ignorance of the novice posters. A consumer can very easily if not shown the comparison between an ''ideal'' and one with moderate to severe leakage choose a larger or less expensive per carat stone just by the stats on paper, a photograph, and then a limited viewing of a small number of non ideal stones in person. That is NOT an informed decision by any stretch of the imagination.

For those who really care about the cut of diamonds the PS community often advocates making thorough comparisons and then making an informed decision. I don''t feel we need to remind the consumer that Superideals cost more, that part is pretty obvious, but pretending that all modern RB are equally beautiful and advocating ignoring the flaws of diamonds like leakage as trivial is simply wrong.

Expressing concern over leakage highlights the fact that there are diamonds in the same cutting style that have better light return and the customer should be aware of this and then make their own subjective judgement on what they feel is most important.

About your bolding part. I am newer here. Been lurking almost a year but only posted about 6 months ago give or take. One thing I will say is that the community here should be doing that, but I do not feel it is always done.

I have seen time and time again someone post a decent stone (not super ideal) and posters come in here and say that they''d pass because it is not super ideal. Unless asked, they do not explain why they pass on the stone. Sometimes posters here even ignore that the person is saying they want one of the 3 other Cs other than cut and tell people to sacrifice what they want just to get a super ideal diamond.

No one is ever going to say that an average cut is the same as a super ideal, but in the fairness of being a consumer, don''t you think it is right to acknowledge that a diamond that is not a super ideal can be beautiful too? I have been given the impression from many that unless it is a RB AGS0 that a diamond is not worth purchasing.

I found this forum to learn even more about gems. And something I think that is forgotten is that not everyone finds cut to be #1 on their list. It may be 2 or 3 and honestly that SHOULD be fine. Yes you can show the differences in diamonds, but if that is what the person is looking for then pushing an ideal or saying "Lower you color, clarity and carat size and you can get X ideal cut" is not helpful either.

I am sure that will not be a popular post here, but really it does bug me when I see it time and time again. Especially when someone says they have some other criteria that is important first.

I will add I am really attempting to learn about diamonds in general now and some day hope to accept a job in the gem world (I am currently a stay at home mother and cannot work outside the home until my child is older) and I hope to be able to educate consumers myself some day. I am not a fan of modern RB diamonds as I have said many times, but this argument intrigues me as someone who really doesn''t really have a personal investment in it. I personally see both sides as valid and think that somewhere in between lies the correct answer and way to educate people. Forcing ideal cut to everyone is not any more right than saying that mathematical equations to find a great stone is absolute bunk.

Cowering back into my cave now

 

[Rockdiamond]

Date: 4/9/2010 10:32:13 AM
Author: Karl_K

Date: 4/9/2010 10:14:10 AM

Author: Rockdiamond

Date: 4/8/2010 11:56:11 PM


Karl has introduced a few terms that I am curious about.


''Scatter'' as opposed to leakage... Karl, what''s the difference?

optics 101

leakage is light not being returned

scatter is light that is returned but not in a useful direction.


A well cut diamond will always have both but will minimize them as much as can be done.

Leakage is not the problem to much and under the table leakage is the problem.

Karl- you used the term "useful direction"
Specifically, which direction is useful?
Follow up question.
How much difference would the direction of that light be , in degrees, if a person wearing a ring moves their hand 1/2 inch?

 

[NJDeac]

Date: 4/9/2010 2:42:54 PM
Author: Rockdiamond
David, we agree- many cutters and dealers don''t like GIA- but I feel that''s because they wanted better grades than they got. These people might even claim that larger companies get better grades. That''s no my experience though....

AS a rule, are you advising consumers to trust HCA over GIA?

Do you refer to HCA on appraisals, or use it to judge value of stones?


If you do recommend the HCA to be used with more confidence that GIA cut grading, it''s good to know. I respect your opinion.


Have you ever had any luck getting GIA to grade stones the way you wanted, as opposed to giving objective results? I have not.

I''ve seen many GIA graded stone who''s color and clarity I disagreed with- yet cases where the disagreement was more than one grade have been virtually non existent in my experience.

Grading is not an exact science , which would account for the single grade difference- it''s opinion.


Compare this to EGL ( particularly the non US ones) and the occurrence of two , three, even four grade differences are relatively common.

What possible negative consequences are there to relying on both? I don''t think anyone is arguing in favor of the HCA as a complete replacement to a cut grade from am ajor lab, but why not only consider stones that perform well as judged by both the GIA and the HCA? What do I, as a consumer, have to lose?

There are enough diamonds out there that it''s not hard to find stones that score well by both metrics. Obviously there''s debate among experts as to the reliability of the HCA, but I don''t see even the harshest critics of the HCA stating that you''re more likely to get a worse looking stone if you rely on it in addition to a GIA excellent rating.

It''s similar to Pascal''s Gambit - maybe all GIA excellent diamonds are beautiful and the HCA is superfluous. But why take that chance where there are so many of them out there that score well on both?