Why did GIA included Steep Deep diamonds in ''Excellent''

[Mara]

Actually Garry hit the nail on the head. Maybe random consumers don''t care AS MUCH about how a diamond looks in the supermarket but the PS niche market, of course they do! They want their diamond to look excellent in as many lighting and viewing situations as possible. It''s part of being the diamond nuts we are.

 

[Garry H (Cut Nut)]

Date: 8/13/2005 1:58:38 PM
Author: Rhino
As I''m reading through the first page of this thread and after performing Garry''s lil experiment I note one contradiction. Belle posted GIA''s response to the ''brightness'' metric and the last sentence of that post says...

These tests confirmed what a vision specialist told us—that when looking at most small objects, a dominant eye takes control.''

Garry... didn''t the point of your test demonstrate that the non dominant eye takes control? This is how it seems to me and contradicts the above statement.

That is the point I was making to Storm Rhino - yes our dominant eyes take control of what we see when all things are equal.

But when there is a very dark zone, or a very bright sparkle, that our non dominant eye sees, and the dominant one does not (because it is looking at a part of the diamond returning light from a beige wall say) THEN the information from the non dominant eye overrides the dominant eye and we see the dark zone or bright sparkle.

Its like Rock Scissors Paper.

(BTW the ''Beige'' joke is my favourite, but is not suitable for audiences below 16)

 

[strmrdr]

Getting back to lighting.
It looks to me like a combo of "white" leds and D65 light sources would produce light with a rather large blue tint rather than pure white light.
Is that currect?
What effect would this have on the diamonds appearance?

Some anti-glare florescent tubes have a strong blue output other than being in a blue room I cant think of any other common environment with a strong blue shift.

Thoughts?

 

[strmrdr]

This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.
Garry can probable do better with it.
Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.
If this is true in the real world then a blue tinted light will make "leaky" diamonds appear better than white light will.

 

[Garry H (Cut Nut)]

Very interesting Storm
(and good to see you playing in the inards of DiamCalc)

 

[belle]

Date: 8/13/2005 7:53:44 PM
Author: strmrdr
This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.
Garry can probable do better with it.
Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.
If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

if it is true, than ANY color light will make ''leaky'' diamonds appear better than white light will.
blue is my favorite color, but since you used that already, i thought i''d try green...

 

[strmrdr]

Date: 8/13/2005 9:43:02 PM
Author: belle

Date: 8/13/2005 7:53:44 PM

Author: strmrdr

This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.

Garry can probable do better with it.

Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.

If this is true in the real world then a blue tinted light will make 'leaky' diamonds appear better than white light will.

if it is true, than ANY color light will make 'leaky' diamonds appear better than white light will.

blue is my favorite color, but since you used that already, i thought i'd try green...

Very good belle it does eliminate contrast.
This could also be why h&a symetry didnt score higher.

 

[adamasgem]

Date: 8/13/2005 7:53:44 PM
Author: strmrdr
This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.
Garry can probable do better with it.
Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.
If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

Storm.. I''m sorry, but DiamondCalc is a NON absorbing ray trace model, and ANY use of uniquely colored light, like what you did, will give you possibly misleading results regarding contrast.

 

[strmrdr]

Date: 8/13/2005 11:26:29 PM
Author: adamasgem

Date: 8/13/2005 7:53:44 PM

Author: strmrdr

This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.

Garry can probable do better with it.

Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.

If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

Storm.. I''m sorry, but DiamondCalc is a NON absorbing ray trace model, and ANY use of uniquely colored light, like what you did, will give you possibly misleading results regarding contrast.

ok.
You have anything that gives better results?
Im real curious to know if it is true and how much effect it would have.

 

[strmrdr]

I do have a question Marty a long time ago I asked about light absorption and ray tracing with diamonds and the answer was that while there was some it wasn''t enough to worry about.
I looks like you have different thoughts on the matter.
Could you explain please?

Garry, sorry for taking this off topic so much but there are some very interesting tangents being brought up and I cant resist :}

 

[Rhino]

Date: 8/12/2005 6:31:52 PM
Author: oldminer
No, I don't think these two firms will work together. The methodology used by Gemex is not oriented to giving discrimination, but rather the kind of happy results vendors and consumers would like to hear. That doesn't mean it is useless, but the lighting inside their black box does not appear to give results which clearly discriminate the best, the near best, very good, etc. I know it appears to do this, but my sources tell me that it is not doing all it is cracked up to be doing. I know you have a relationship with them and truly want to aid the consumer. It isn't your desire to help that is underachieving, but the product makes for unsupported results.


I would welcome the opportunity to test some diamonds as a comparison for you and other dealers, vendors. No charge! No secrets.
Constructive criticism is not unwelcome. I believe many firms in this arena want to show how their products work. Knowing the truth will be very powerful. I'd be willing to risk it for the sake of bettering the business. Maybe we can all get the ball rolling.

Catching up on some reading here. Dave I would love to participate with you in this experiment. Perhaps we can post the results on mine or your website or just right here on the forum; comparing diamonds, lightscope images, Sarin/Helium results, imagem results, brilliancecope, virtual models and isee2 results just for sake of comparison on various diamonds? I think it would be a gas.

 

[strmrdr]

Date: 8/14/2005 12:54:49 AM
Author: Rhino

Date: 8/12/2005 6:31:52 PM

Author: oldminer

No, I don''t think these two firms will work together. The methodology used by Gemex is not oriented to giving discrimination, but rather the kind of happy results vendors and consumers would like to hear. That doesn''t mean it is useless, but the lighting inside their black box does not appear to give results which clearly discriminate the best, the near best, very good, etc. I know it appears to do this, but my sources tell me that it is not doing all it is cracked up to be doing. I know you have a relationship with them and truly want to aid the consumer. It isn''t your desire to help that is underachieving, but the product makes for unsupported results.



I would welcome the opportunity to test some diamonds as a comparison for you and other dealers, vendors. No charge! No secrets.

Constructive criticism is not unwelcome. I believe many firms in this arena want to show how their products work. Knowing the truth will be very powerful. I''d be willing to risk it for the sake of bettering the business. Maybe we can all get the ball rolling.

Catching up on some reading here. Dave I would love to participate with you in this experiment. Perhaps we can post the results on mine or your website comparing diamonds, lightscope images, Sarin/Helium results, imagem results, brilliancecope and isee2 results just for sake of comparison on various diamonds?

That would be awesome I hope you 2 can work it out and make it happen.

 

[Rhino]

Garry... just for fun run this stone through the new beta DiamCalc. I''d be curious to see how it fares on the new AGS system. It has a rather interesting set of proportions and ASET image too.

http://www.goodoldgold.com/1_01ct_k_si1.htm

 

[Rhino]

Is there a light condition where a ''leaky'' stone would have an advantage?
Backlight is likely one are there others?

Yep. Diamonds in jewelry stores are often shown above a showcase where lighting is taking place and this helps the appearance of leaky stones along with the intense lights jewelry stores typically have from above. That combination does a heluva job of making kaka look good.

Other backlight conditions are actually none at all but a white background. It makes a leaky diamond appear "light" which most consumers interpret as "whiter" = better. We demonstrate how faulty this is and one of the best viewing environments in my personal opinion would be that of moderate natural ambient daylight observed in a faux setting (when comparing stones that are loose) and up against the neutral background OF SKIN. After all the diamond is being worn on a HAND which brings me to this conclusion.

I don''t agree with neither white nor black as this emphasizes too much brightness or darkness either way. I still have to think through the *gray* issue more but one background I don''t have to think twice about is that of skin or a skin toned color. THAT is the most common backlit condition that diamonds are viewed against.

 

[Rhino]

Date: 8/13/2005 12:53:43 AM
Author: Garry H (Cut Nut)

Date: 8/12/2005 10:33:05 PM
Author: strmrdr
Hey i just thought of a good demo.
Asschers achieve their patterns by using leakage thru some facets.
I encourage vendors to use a dark background to make the patterns stand out and its easier to see miscut facets.
So my idea is get someone to shoot an asscher against a black, white , and gray background and in one of those fake ring stone holders in the same lighting.
This will give an exagerated idea of the effects of the background when compared to rounds but it will make it plainly visible.
What say you?

An excellent idea Storm.
And if you can get 3D Sarin or Helium files for the stones you can also model them in DiamCalc and use different backgrounds - you do know that the different backgrounds introduce different amounts of back lighting into the virtual stone?

(this type of photography - letting light in the pavilion - has always seemed very deceptive to me - some of you may notice that I get rather short with vendors that do it. It led to me being banned at DT, and a spat with a DT member who posts here recently)

I have an extremely busy week laid out for me but at first chance I''ll do it guys. I have the perfect Asscher for the project too.

 

[Rhino]

Date: 8/13/2005 5:38:42 PM
Author: Garry H (Cut Nut)

Date: 8/13/2005 1:58:38 PM
Author: Rhino
As I''m reading through the first page of this thread and after performing Garry''s lil experiment I note one contradiction. Belle posted GIA''s response to the ''brightness'' metric and the last sentence of that post says...

These tests confirmed what a vision specialist told us—that when looking at most small objects, a dominant eye takes control.''

Garry... didn''t the point of your test demonstrate that the non dominant eye takes control? This is how it seems to me and contradicts the above statement.

That is the point I was making to Storm Rhino - yes our dominant eyes take control of what we see when all things are equal.

But when there is a very dark zone, or a very bright sparkle, that our non dominant eye sees, and the dominant one does not (because it is looking at a part of the diamond returning light from a beige wall say) THEN the information from the non dominant eye overrides the dominant eye and we see the dark zone or bright sparkle.

Its like Rock Scissors Paper.

(BTW the ''Beige'' joke is my favourite, but is not suitable for audiences below 16)

 

[adamasgem]

Date: 8/13/2005 11:51:28 PM
Author: strmrdr

Date: 8/13/2005 11:26:29 PM
Author: adamasgem

Date: 8/13/2005 7:53:44 PM

Author: strmrdr

This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.

Garry can probable do better with it.

Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.

If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

Storm.. I''m sorry, but DiamondCalc is a NON absorbing ray trace model, and ANY use of uniquely colored light, like what you did, will give you possibly misleading results regarding contrast.

ok.
You have anything that gives better results?
Im real curious to know if it is true and how much effect it would have.

Well Storm
1) It is basic physics using Beer''s Law, so my statement is true
2) My 3D ray trace is forward monte-carlo, and I can and have generated WLR type statistics using SAS2000 spectra on type IIa diamond spectra where I have direct and fairly accurate knowlege of the absorption charateristics versus wavelength for a known pathlength basd on flat plate (CVD diamond) spectra where I know the transmittance characteristics and the nominal pathlength. I have some Type Ia macle to take spectra on, where I can get data on a "known" pathlength, and then generate absorption vs wavelength

3) My software does not yet have a reverse 3D ray trace to do "photo real" commercially oriented renderings, and I don''t have the time to do it in the near future, as I have too much on my plate right now, perhaps in the future, but then I would wind up competing with DiamondCalc, since I like to get paid for my work. Probaly only take me two or three man months of software effort to do it.

4) If you take a look at my website you will see normalized spectra of type Ia diamonds, which show how, dependent on the nitrogen concentration, diamonds major absorption is concentrated below 500 nm, however there is NON negligible absorption, but uniform, even when the diamond is a "D" color. D colors still absorb light, but more uniformly, unless of course we have New GIA D''s (versus the old 50 year definition of a D), where you pump in as much ultraviolet as possible to bump up the color grade. It is all about $.

So I''d be happy to do the correct job for the trade, but when I sought funding from the JCK fund for research, I was told I was a one man band and the moneys available always went to the likes of GIA and JVC

My research and efforts are available to my SAS2000 clients, and I have to address their needs first, and also try to pay the bills at the same time..

 

[Garry H (Cut Nut)]

Marty you should know better than underestimate Sergey

Date: 8/13/2005 11:26:29 PM
Author: adamasgem

Date: 8/13/2005 7:53:44 PM
Author: strmrdr
This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.
Garry can probable do better with it.
Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.
If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

Storm.. I''m sorry, but DiamondCalc is a NON absorbing ray trace model, and ANY use of uniquely colored light, like what you did, will give you possibly misleading results regarding contrast.

Check out under gem materials where you can select absorption.
Marty do you actually have Diamcalc?

 

[adamasgem]

Date: 8/13/2005 11:55:41 PM
Author: strmrdr
I do have a question Marty a long time ago I asked about light absorption and ray tracing with diamonds and the answer was that while there was some it wasn''t enough to worry about.
I looks like you have different thoughts on the matter.
Could you explain please?

Garry, sorry for taking this off topic so much but there are some very interesting tangents being brought up and I cant resist :}

Well, I wasn''t the one that said that, I''m damn sure of that..

When I did some 3D ray tracing on type IIa spectra I had from flat plates, I showed something like a factor of 2 reduction in the GIA WLR metric, for what I believe would be a F-G-H color stone if cut to a 6mm RBC. (I can''t say for sure as I haven''t done the necessary modeling yet to compute resultant color grade). I have to look at my software to see how I can generate the required results by saving intermediate data as a function of wavelength.

What is going to be significantlly effect is any chromatic flare metric...

Cutters have learned how to INTENSIFY the color in radiant cuts, to getthe lucky vivid color call in fancy yellows..

The simplest example is when you look through the table to open culet window in an Old European cut, The center looks much lighter (and also shows the background)

 

[strmrdr]

Marty,
I wasnt questioning your statement above when I said:
"Im real curious to know if it is true and how much effect it would have."
What I was talking about was if the tinted light reduces contrast is true and if it was enough to affect the outcome of the study.

I think you may have misunderstood what I ment and I wasnt the clearest.

I can understand needing to get the bills paid first.
Thanks for taking the time to help me learn here.

 

[adamasgem]

Date: 8/14/2005 3:16:03 AM
Author: Garry H (Cut Nut)
Marty you should know better than underestimate Sergey

Date: 8/13/2005 11:26:29 PM
Author: adamasgem

Date: 8/13/2005 7:53:44 PM
Author: strmrdr
This isnt very good but I started out with the jewelery store lighting in diamcalc and changed some of the sources to blue.
Garry can probable do better with it.
Playing around with it I found that the blue tint tended to decrease the contrast between the dark areas and the light areas.
If this is true in the real world then a blue tinted light will make ''leaky'' diamonds appear better than white light will.

Storm.. I''m sorry, but DiamondCalc is a NON absorbing ray trace model, and ANY use of uniquely colored light, like what you did, will give you possibly misleading results regarding contrast.

Check out under gem materials where you can select absorption.
Marty do you actually have Diamcalc?

Yes Gary, I have a licensed copy that I bought years ago on another laptop..
And I don''t under estimate Sergey, he is one of the few who knows what he is doing..

Why don''t you present some absorbing diamond renderings, since you play with it all the time and I don''t. And show the difference with an non absorbing rendering along with the differing metrics.

 

[Garry H (Cut Nut)]

Date: 8/14/2005 1:21:09 AM
Author: Rhino
Garry... just for fun run this stone through the new beta DiamCalc. I''d be curious to see how it fares on the new AGS system. It has a rather interesting set of proportions and ASET image too.

http://www.goodoldgold.com/1_01ct_k_si1.htm

Steep crown - about 36.1
Shallow pavilion about 40.2 avg''s
Table is biggish - about 60
AGS 3
But the lower girdles are a bit too long so fire should be down a little - sym is off - but not a bad stone.

 

[strmrdr]

Date: 8/14/2005 3:30:31 AM
Author: adamasgem

Date: 8/13/2005 11:55:41 PM

Author: strmrdr

I do have a question Marty a long time ago I asked about light absorption and ray tracing with diamonds and the answer was that while there was some it wasn''t enough to worry about.

I looks like you have different thoughts on the matter.

Could you explain please?


Garry, sorry for taking this off topic so much but there are some very interesting tangents being brought up and I cant resist :}

Well, I wasn''t the one that said that, I''m damn sure of that..


When I did some 3D ray tracing on type IIa spectra I had from flat plates, I showed something like a factor of 2 reduction in the GIA WLR metric, for what I believe would be a F-G-H color stone if cut to a 6mm RBC. (I can''t say for sure as I haven''t done the necessary modeling yet to compute resultant color grade). I have to look at my software to see how I can generate the required results by saving intermediate data as a function of wavelength.


What is going to be significantlly effect is any chromatic flare metric...


Cutters have learned how to INTENSIFY the color in radiant cuts, to getthe lucky vivid color call in fancy yellows..


The simplest example is when you look through the table to open culet window in an Old European cut, The center looks much lighter (and also shows the background)

Thanks Marty
Interesting info.
No it wasnt you that said that back then.

 

[adamasgem]

Date: 8/14/2005 3:35:17 AM
Author: strmrdr
Marty,
I wasnt questioning your statement above when I said:
''Im real curious to know if it is true and how much effect it would have.''
What I was talking about was if the tinted light reduces contrast is true and if it was enough to affect the outcome of the study.

I think you may have misunderstood what I ment and I wasnt the clearest.

I can understand needing to get the bills paid first.
Thanks for taking the time to help me learn here.

Hi Storm.. well Gary just piped in and said DiandCalc can do it, so I guess he can present the reverse ray trace "truth". I''d like to know what absorption coefficient verses wavelength he is using though. A constant coeficient doesn''t cut it..
Surprising he hasn''t done it before..

 

[Garry H (Cut Nut)]

Date: 8/14/2005 3:14:33 AM
Author: adamasgem

Storm:
ok.
You have anything that gives better results?
Im real curious to know if it is true and how much effect it would have.

Well Storm
1) It is basic physics using Beer''s Law, so my statement is true
2) My 3D ray trace is forward monte-carlo, and I can and have generated WLR type statistics using SAS2000 spectra on type IIa diamond spectra where I have direct and fairly accurate knowlege of the absorption charateristics versus wavelength for a known pathlength basd on flat plate (CVD diamond) spectra where I know the transmittance characteristics and the nominal pathlength. I have some Type Ia macle to take spectra on, where I can get data on a ''known'' pathlength, and then generate absorption vs wavelength

3) My software does not yet have a reverse 3D ray trace to do ''photo real'' commercially oriented renderings, and I don''t have the time to do it in the near future, as I have too much on my plate right now, perhaps in the future, but then I would wind up competing with DiamondCalc, since I like to get paid for my work. Probaly only take me two or three man months of software effort to do it.

My research and efforts are available to my SAS2000 clients, and I have to address their needs first, and also try to pay the bills at the same time..

Marty if you are thinking about competing with DiamCalc you probably should have a play with your old version which has the Gem Materials Tab.
And for about $50 you can upgrade to the 2.3 version.
The 2.4 will be released very soon, and Sergey is thinking to make it a free upgrade - although with all the new bells and whisltes, there is no reason why it should not be more like $1,000.

At this link I have done a screen shot example for you:
https://www.pricescope.com/community/threads/user-tips-for-diamcalc.32366/

 

[RockDoc]

Garry

I have Diamond Calc 1.8, but I couldn''t make it work (Im a computer grape).

Even with trying to lock in the measurements, I found the results not what I judged to be reliable.

Does the Diamond Calc 2.4 work with the Sarin for actual scans?


The other problem I have is that I use different computers for different equipment, so beling limited to run it on one computer, and having to buy multiple versions in order to run it in different places is financially prohibitive.

I also have gem advisor and when I try to view something with it, it tells me my old version expired, and even if I download the newer version it still doesn''t work, at least for me anyhow.

So can I upgrade for $ 50.00 and install the new version on different computers?

If so I''d give it a second chance.

Rockdoc

 

[Garry H (Cut Nut)]

Roc as a proffessional with maybe 100k of equipment, i think you need to spend a whopping $320 (+P&H) for the HASP key version that you load a CD onto any or all computers, and simply plug the HASP into the one you wish to use.

But best wait a week or 2 until we have the new version.
It is so amazing that you will hear about it.

I think with Gemadviser you probably need to clear out the old folder so you have a fresh start.

The locking of numbers on DiamCalc still applies - if you try to make a stone that can never exist - it will frustrate you.

 

[adamasgem]

Date: 8/14/2005 4:30:01 AM
Author: Garry H (Cut Nut)

Date: 8/14/2005 3:14:33 AM
Author: adamasgem

Storm:
ok.
You have anything that gives better results?
Im real curious to know if it is true and how much effect it would have.

Well Storm
1) It is basic physics using Beer''s Law, so my statement is true
2) My 3D ray trace is forward monte-carlo, and I can and have generated WLR type statistics using SAS2000 spectra on type IIa diamond spectra where I have direct and fairly accurate knowlege of the absorption charateristics versus wavelength for a known pathlength basd on flat plate (CVD diamond) spectra where I know the transmittance characteristics and the nominal pathlength. I have some Type Ia macle to take spectra on, where I can get data on a ''known'' pathlength, and then generate absorption vs wavelength

3) My software does not yet have a reverse 3D ray trace to do ''photo real'' commercially oriented renderings, and I don''t have the time to do it in the near future, as I have too much on my plate right now, perhaps in the future, but then I would wind up competing with DiamondCalc, since I like to get paid for my work. Probaly only take me two or three man months of software effort to do it.

My research and efforts are available to my SAS2000 clients, and I have to address their needs first, and also try to pay the bills at the same time..

Marty if you are thinking about competing with DiamCalc you probably should have a play with your old version which has the Gem Materials Tab.
And for about $50 you can upgrade to the 2.3 version.
The 2.4 will be released very soon, and Sergey is thinking to make it a free upgrade - although with all the new bells and whisltes, there is no reason why it should not be more like $1,000.

At this link I have done a screen shot example for you:
https://www.pricescope.com/community/threads/user-tips-for-diamcalc.32366/

Gary.. It turns out I already have 2.3.1 I stand corrected as I haven''t played with DiamondCalc for quite a while, and hadn''t realized he had put that in. I guess someone must be listening to me.

I really have no intention of "competing" with DiamondCalc, I have done my own analyses in my SAS2000 software because I KNOW what is in it, as to the modeling, etc.

Don''t get me wrong, I have ALWAYS said that DiamondCalc can be a very usefull tool, if used correctly, only I don''t believe that limited viewpoint metrics are "correct" for the consumer, BUT they can be much better that what has been done for years.

Your single point absorption model shows something, although I''m not sure what it is as you didn''t present a comparison between no absorption and a "real" absorption model, and from the values for absorption you used at 480nm, it is readily apparent that you may not completely understand Beer''s law.

Why don''t you get a "correct" 1mm thick absorption spectrum from Sergey and see what you can come up with and post it here.

Suggestion: The "Galoconda perfect D" non absorbing model typically used should not be baseline for DiamondCalc

 

[adamasgem]

Date: 8/14/2005 1:30:26 AM
Author: Rhino

Is there a light condition where a ''leaky'' stone would have an advantage?
Backlight is likely one are there others?

Yep. Diamonds in jewelry stores are often shown above a showcase where lighting is taking place and this helps the appearance of leaky stones along with the intense lights jewelry stores typically have from above. That combination does a heluva job of making kaka look good.

Other backlight conditions are actually none at all but a white background. It makes a leaky diamond appear ''light'' which most consumers interpret as ''whiter'' = better. We demonstrate how faulty this is and one of the best viewing environments in my personal opinion would be that of moderate natural ambient daylight observed in a faux setting (when comparing stones that are loose) and up against the neutral background OF SKIN. After all the diamond is being worn on a HAND which brings me to this conclusion.

I don''t agree with neither white nor black as this emphasizes too much brightness or darkness either way. I still have to think through the *gray* issue more but one background I don''t have to think twice about is that of skin or a skin toned color. THAT is the most common backlit condition that diamonds are viewed against.

Rhino..
1) "skin" is not a neutral background
2) I posted the absorption spectra of skin types on that long AGS cut grade thread when I got into an argument with Gary about the "black hole" head obsuration model.
3) The lower angle lighting incident on the crown of the diamond may come partially from skin reflections
4) The background issue is complicated and SO VARIABLE due to skin/mounting, etc, that, in MY OPINION, non reflecting black should be used for photos and metrics

 

[adamasgem]

Date: 8/14/2005 3:52:05 PM
Author: Garry H (Cut Nut)
Roc as a proffessional with maybe 100k of equipment, i think you need to spend a whopping $320 (+P&H) for the HASP key version that you load a CD onto any or all computers, and simply plug the HASP into the one you wish to use.

But best wait a week or 2 until we have the new version.
It is so amazing that you will hear about it.

I think with Gemadviser you probably need to clear out the old folder so you have a fresh start.

The locking of numbers on DiamCalc still applies - if you try to make a stone that can never exist - it will frustrate you.

It will be interesting to see whether one HASP key interferes with another when you daisy chain them on a single computer. I use one on my SAS2000 system.

Regarding Roc''s problem with DaimondCalc, If he unlocks the total depth and then builds the stone from the top (table) down, it might solve some frustrations. One of the problems is, is that using "averages" of table size, angles, etc, from the Sarin doesn''t always work out as to getting the same measured depth.

In my software, where there is confidence in the depth measurement, I lock the "true" depth and let the girdle "float"..
As you say, the parameters have to be mathematically consistent, or else you get a stone that cannot exist..

In a generic symmetrical model, as an example, crown height, table size and crown angle are mathematically tied together as is pavillion ange, culet size and pavilion depth.

The culet size and the "average" girdle are the two most difficult measurements in my opinion, based on what I have seen and studied from a limited number of manufacturer''s reports