Several questions for Garry and other cut experts.......????

[Maxine]

Hi!
Related to the steep-deep topic, I have several questions.......

I know that a steep-deep diamond shows a ring of leakage on (around ) the table.
But, can a shallow-shallow or shallow-deep or shallow avg. stone show be identified by any particluar characteristic on the IS?????? In other words, a shallow-shallow really isn''t leaking light is it?? (But "something" causes parts of it to "go dark"....)

Do you have any ACTUAL IS photos of S-D and S-S stones to compare???

Also, if S-D looks best in open setting, (and S-S stone looks best w/dirty pavillion), should S-S stone be set in like a bezel or w/other stones next to it as in 3-stone????

One more thing : when is steep-deep (measurements)???? shallow-shallow?
Does shallow-shallow take same hit on cut grading????

Just curious...

 

[Garry H (Cut Nut)]

http://www.ideal-scope.com/using_reference_chart.asp reference chart with shallow stone examples.

Newsletter that discusses head obstruction of light sources http://www.ideal-scope.com/newsletters_issue004.asp

picture of reference chart:

 

[Maxine]

Thanks...so if I''m reading it right, shallow has pink center????


Any particular measurements at which a stone becomes Shallow or deep????

 

[Garry H (Cut Nut)]

shallow will start to show signs of very shallow - especially if you tilt the stone slightly - which shows what each eye would see - you can learn about that in the current debate about GIA leakage in the AGS thread pinned at the top and the old GIA thread Maxine

 

[strmrdr]

Date: 8/28/2005 9:12:59 PM
Author: Maxine
Thanks...so if I''m reading it right, shallow has pink center????



Any particular measurements at which a stone becomes Shallow or deep????

Not always.
Since the IS mainly deals with direct lighting light return and the steep/shallow and shallow/shallow combos can perform well in direct light they can pass the IS test.
Its in indirect light that those combos fail.

steep-deep combos fail in direct light and for the most part in indirect light also.
Im working on a explaination of this but its taking far longer than I imagined.
The biggest problem is deciding where to draw the lines.
This may change but for now:
In general:
34.9+ is steep
41+ is steep

34.3-34.8 is normal
40.7-40.9 is normal

40.6 and under is shallow
34.3 and under is shallow.

The problem?
35.4/40.6 is an awesome combo and is very steep/shallow
So there needs to be another bit of data added in.
The hca fits the bill fairly well.
So far if the hca score is over 1 the combo is safe.
The problem?
Not all hca scores under 1 are bad.

So it has to be a 2 part equation which equals confusion.

Im trying to simplify it and present it in an understandable manner.

 

[Maxine]

So , if the COMBO works well on the HCA, that''s better?

My stone has shallower crown, don''t know PA, w/ avg. depth......looks like ideal cut on IS...It doesn''t look like view of shallow...def not very shallow....Is it considered shallow-??

When I DO reset it I will get it professionally measured (sarin?).....

So what is the best setting for a shallow avg stone? Anything that will maximize it''s relative stengths???? I don''t really notice the dark spot (but then again my KIDS are no longer in their 20''s.................) Maybe similar to what it is now, w 6 prongs.....not as open as 4.....

 

[strmrdr]

Date: 8/28/2005 9:45:18 PM
Author: Maxine
So , if the COMBO works well on the HCA, that's better?


My stone has shallower crown, don't know PA, w/ avg. depth......looks like ideal cut on IS...It doesn't look like view of shallow...def not very shallow....Is it considered shallow-??


When I DO reset it I will get it professionally measured (sarin?).....


So what is the best setting for a shallow avg stone? Anything that will maximize it's relative stengths???? I don't really notice the dark spot (but then again my KIDS are no longer in their 20's.................) Maybe similar to what it is now, w 6 prongs.....not as open as 4.....

If the hca score is over 1 and under 2 none of the above matters that iv been able to find.
The combo is good.
There might be some personality differences but not quality differences.


shallowish crown/normal to slightly steep pavilian can be an awesome combo.
With the proper minors it can be one of the brightest diamonds available.
They work well in any setting.

 

[strmrdr]

Those ranges as presented arent going to work.
34.3/40.6 would be considered a shallow/shallow.

I do think iv hit on the rule however.
If the hca is under 1 and the pavilion is 40.6 or under then run.

 

[belle]

Date: 8/29/2005 8:51:18 AM
Author: strmrdr

I do think iv hit on the rule however.
If the hca is under 1 and the pavilion is 40.6 or under then run.

i will have to look in to that!

 

[strmrdr]

Date: 8/29/2005 9:22:11 AM
Author: belle

Date: 8/29/2005 8:51:18 AM

Author: strmrdr


I do think iv hit on the rule however.

If the hca is under 1 and the pavilion is 40.6 or under then run.

i will have to look in to that!

Thank you :}
DC jewlery store lighting the tail will tell.
It has the head shadow to show it.

 

[Regular Guy]

Date: 8/29/2005 9:50:30 AM
Author: strmrdr

Date: 8/29/2005 9:22:11 AM
Author: belle

Date: 8/29/2005 8:51:18 AM

Author: strmrdr


I do think iv hit on the rule however.

If the hca is under 1 and the pavilion is 40.6 or under then run.

i will have to look in to that!

Thank you :}
DC jewlery store lighting the tail will tell.
It has the head shadow to show it.

So, you''re saying the evidence for you is in the DC jewelry store lighting view only in DC?

FYI, I see one in evidence today in the cut by search db, and -- coincidentally or not -- not referring to that view, I tried to do an analysis of that one earlier today (starting with second item down, but especially 3rd one down from the top).

I''m not seeing DC right now. But, does this confirm your view?

 

[Sundial]

I don''t want to hijack Maxine''s thread, but want to make sure I understand this. If my diamond has a steep crown angle at 34.9, normal pavillion at 40.8, depth 61.8%, table 55% is it considered steep/deep? If the HCA is 1.5 then is the combination considered okay?

 

[strmrdr]

Date: 8/29/2005 10:10:19 AM
Author: Sundial
I don''t want to hijack Maxine''s thread, but want to make sure I understand this. If my diamond has a steep crown angle at 34.9, normal pavillion at 40.8, depth 61.8%, table 55% is it considered steep/deep? If the HCA is 1.5 then is the combination considered okay?

its fine.

 

[strmrdr]

RG compare the 2 images here:

http://www.dirtcheapdiamonds.com/diamond_detail.cfm?did=8557558

61.3% depth, 55% table, 34.9° crown angle, 40.7°
hca 1.1
The diamond is slightly tilted.
Its fine.


60.9% depth, 56% table, 34.8° crown angle, 40.5° pavilion angle
hca .4

http://www.dirtcheapdiamonds.com/diamond_detail.cfm?did=8187868&ref=PS622

Notice how the first looks brighter and the second darker under the table.
The arrow shafts are too dark. They wont be returning light.

Not picking on DCD the first is a very nice diamond for a ring :}
The second is the better diamond for a pendant or ear ring :}
The images however tell the story im trying to tell.

 

[Regular Guy]

Thanks, Storm, but this is too ephemeral for me, anyway. Could we go back to my original question?

Date: 8/29/2005 10:04:39 AM
Author: Regular Guy

Date: 8/29/2005 9:50:30 AM
Author: strmrdr

Date: 8/29/2005 9:22:11 AM
Author: belle

Date: 8/29/2005 8:51:18 AM

So, you''re saying the evidence for you is in the DC jewelry store lighting view only in DC?

Using the same viewer, i.e., DCD, and another diamond with an HCA score of 1 (61 depth, 57 table, 34.5 crown, 40.7 pav, 6.54 diameter x 3.99), the arrows look pretty dark to me, there, too.

 

[strmrdr]

RG compare the hca 1 diamonds image to the hca .4
The area around the arrows is a lot darker in the hca .4 one.
The one with an hca score of 1 the light is being returned thru the table in the other it isnt.
That is what is mant by poor contrast.
The difference between the darks and lights areas under the table.

 

[Regular Guy]

Date: 8/29/2005 11:33:19 AM
Author: strmrdr
RG compare the hca 1 diamonds image to the hca .4
The area around the arrows is a lot darker in the hca .4 one.
The one with an hca score of 1 the light is being returned thru the table in the other it isnt.
That is what is mant by poor contrast.
The difference between the darks and lights areas under the table.

Storm, you may be right, but I''d be grateful for either a novice or expert to confirm what you''re seeing.

As a methodology, this example certainly helps explain why I prefer a system like HCA over the various visual media, including IS, and now this.

Seems like, at this point, maybe I better find something better to do. I''m just not sure I can reliably enough suggest anything to anybody about these things, without having made more observations, helping me to correlate with my own eyes the nice aesthetic any of these systems purport to explain, however internally logically consistent they may be.

To the other poster in the other thread with the ACA...I''m guessing you have a beauty...but I don''t blame you for wanting to double check these things.

Regards,

 

[strmrdr]

RG its complicated Im working on simplifying the explaination and examples.
Getting it easy enough to understand is a problem.
I will post more here tonight.

 

[belle]

Date: 8/29/2005 12:48:15 PM
Author: Regular Guy
I''m just not sure I can reliably enough suggest anything to anybody about these things, without having made more observations, helping me to correlate with my own eyes the nice aesthetic any of these systems purport to explain, however internally logically consistent they may be.

i am with you on this rg.
not to mention that these are subtle nuances in superbly cut stones we are trying to split hairs with here. those that see and compare diamonds daily may be able to tell the difference, but i wouldn''t want to try and make that distinction.

 

[strmrdr]

Date: 8/29/2005 1:09:54 PM
Author: belle

Date: 8/29/2005 12:48:15 PM

Author: Regular Guy

I''m just not sure I can reliably enough suggest anything to anybody about these things, without having made more observations, helping me to correlate with my own eyes the nice aesthetic any of these systems purport to explain, however internally logically consistent they may be.

i am with you on this rg.

not to mention that these are subtle nuances in superbly cut stones we are trying to split hairs with here. those that see and compare diamonds daily may be able to tell the difference, but i wouldn''t want to try and make that distinction.

Thats the thing belle Iv seen this with my own eyes and so would you if it was pointed out or you looked for it.
There can be as big if not a bigger difference in indirect light as the difference in direct light between an hca score of 1.5 and an hca score of 2.5 an no one thinks that is splitting hairs too fine.
Like anything else there are going to be borderline cases like an hca 2.1 diamond that may be very beatiful.
Its a tough one presentation wise.
More tonight.

 

[strmrdr]

Iv decided to go back to trying to get my presentation together off the board before I present more of it.
For now use caution if the hca scores are under 1 and the pavilion facets are 40.6 or under.
Trying to present it spure of the moment is causing too much confusion.

 

[Dancing Fire]

when i was looking to buy .25ct stones for my wife''s w-band.Brian from WF told me that he doesn''t mind the 41'' pavil on smaller stones. some of his smaller size ACA are in fact cut to 41.1'' pavil.

 

[JohnQuixote]

Date: 8/29/2005 11:15:53 PM
Author: Dancing Fire
when i was looking to buy .25ct stones for my wife''s w-band.Brian from WF told me that he doesn''t mind the 41'' pavil on smaller stones. some of his smaller size ACA are in fact cut to 41.1'' pavil.

True. ACA PA cutoff is usually 40.9 in larger goods. The 41PAs are often less than .50 ct (most are melee) and perform well due to facet size and sparkle - for the same reason a disco ball with tiny mirrors looks more scintillating than if it was coated in large mirrors.

 

[Demelza]

It seems like there have been quite a few threads like this as of late (i.e. people concerned that their ideal cut diamonds are somehow lacking in some very important way because they're "off" by a tenth of a degree). I'm not questioning whether those who say that there is, for instance, an appreciable visual difference between a 40.6 vs. 40.7 pavilion angle are right or wrong; I'm questioning whether it is at all helpful to try to split already split hairs, to make absolute declarations that any diamond that falls outside the narrowest parameters is a poor performer. It may be that some people simply don't like stones that have a pavilion angle of 40.6 or an HCA less than 1, but I think it's very important to remember that these are opinions and that the industry's debate over what makes a diamond ideal is far from resolved. I went through tremendous angst because my new diamond has a pavilion angle of 40.6. I researched up and down, right and left, high and low, to find some conclusive evidence that a tenth of a degree would negatively impact the appearance of the stone. Some experts said there's no problem, a couple said the diamond needed to be seen in order to evaluate the impact of the shallower pav angle. Finally I gave up and decided to trust my eyes. I'm glad I did because this diamond looks as good if not better in indirect lighting than my last diamond which had a pavilion angle of 40.7. I think it's very unfortunate that so many of us, it seems, doubt the beauty of our diamonds -- diamonds that are, as Belle has said, cut better than most of the rough in the world. The question is: is the doubt a result of something we're actually SEEING or is it because of a NUMBER on a sarin report? I'm not wanting to stir the pot or discount the validity of Storm's observations; I just worry sometimes that all this minutia might actually be doing some of us more harm than good.

 

[WinkHPD]

I think you have hit the nail on the head! Using your eyes is the ultimate confirmation of what you think the stone looks like. All of the paper is nice, and we can split hairs until even the mathmatitians are dizzy, but if the stone is beautiful, it is beautiful.

Storm, I have to take some dissagreement with your contention to be careful of stones with an HCA of less than one. I have sold many with HCA''s in the 0.6 to 0.9 range and they have all been real lookers that my clients are very happy with.

Gary and Paul Slegers have both commented that sometimes a stone near the edge of the parameters will actually have superior performance because of the contrast than a stone dead bang in the middle of the ideal parameters.

I like the fact that we can have numbers and angles tell us what a stone should look like, but it is the seeing that is both the proof of and the joy of the pudding.

Wink

 

[strmrdr]

Date: 9/2/2005 8:52:42 AM
Author: Wink
I think you have hit the nail on the head! Using your eyes is the ultimate confirmation of what you think the stone looks like. All of the paper is nice, and we can split hairs until even the mathmatitians are dizzy, but if the stone is beautiful, it is beautiful.


Storm, I have to take some dissagreement with your contention to be careful of stones with an HCA of less than one. I have sold many with HCA''s in the 0.6 to 0.9 range and they have all been real lookers that my clients are very happy with.


Gary and Paul Slegers have both commented that sometimes a stone near the edge of the parameters will actually have superior performance because of the contrast than a stone dead bang in the middle of the ideal parameters.


I like the fact that we can have numbers and angles tell us what a stone should look like, but it is the seeing that is both the proof of and the joy of the pudding.


Wink

Howdy Wink :}
I cant agree more use your eyes! Just make sure and check the diamond in indirect light. The performance there is just as important as in direct light. :}

As you can tell by my responces above this is a work in progress and is going to take a lot longer than I ever expected.
I have verified it to be a problem in some combos with my own eyes.
The problem becomes where to draw the line.
It is more complicated than hca > 2 no go. Which also can cut out some very nice but not top end diamonds.
Most of the research and tools has gone into direct light performance.

The isee2 project being one exception.

Michael Cowing being another with his exellent work on contrast brilliance.

When my research is further along I look forward to discussing it with you on the board. For now I need to go private with it.