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GIA Ex: The Consumers Perspective and the Technologies
- Thread starter Rhino
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dhog
Shiny_Rock
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Rhino wrote: Why put the diamonds against a black background or even a bright white background?
if you are running windows software go to the display
properties, under appearance and change the color scheme
over to high contrast white. apply the setting and go back
to your desktop. you should have a bright background of white.
after doing this go back in and change it again
this time change it to high contrast black
this should help explain the reasons for thier test
if you are running windows software go to the display
properties, under appearance and change the color scheme
over to high contrast white. apply the setting and go back
to your desktop. you should have a bright background of white.
after doing this go back in and change it again
this time change it to high contrast black
this should help explain the reasons for thier test
re:Then we are in agreement with this comparison Serg. Let me also make note and one correction to your statement. It has been said that GIA gives hits to all painted stones. According to our research into this matter, this is indeed not the case. To my knowledge it is only to the point where it impacts face up appearance.
Rhino,
Please give more information.
Do you mean :
1)If painted is too small than GIA does not penalty such diamond . This case is not interesting at all.
Or
2) GIA can give Excellent to painted ( at least 1 click) diamond . It is very interesting . do you have any examples? I have only opposite examples
Rhino,
Please give more information.
Do you mean :
1)If painted is too small than GIA does not penalty such diamond . This case is not interesting at all.
Or
2) GIA can give Excellent to painted ( at least 1 click) diamond . It is very interesting . do you have any examples? I have only opposite examples
Re: Serg.You have done perfect demonstration that method of GIA research on the base of PARAMETRICAL diamond model and on the base of direct measurement method can easily mislead any researcher. You came to the same snare of method like GIA researchers.
Re: Rhino. I don't understand your last comment Serg because I stand in full agreement with everything you state here including your last comments regarding the stars in combination with the painting. It appears we are very much on the same page. My research into the GIA system regarding these issues also concurs.
Rhino,
1)Take standard diamond, Check different star facets( 40%, 50%,60%) . You will receive more or less same diamonds( same Brilliance, pattern is different of course. Much more easy to control diamcalc face up LR Crown and TABLE ). You can see it for other normal proportions too. Logical conclusion :" Stars facets in range 40-50% are not critical for cut grades"( It is not mine conclusion!, it is just Logical conclusion.)
2) to take parametrical painted diamond( or may be better pained diamond) with exactly same average parameters( like painted diamonds from your example, which model and photo you published on PS). See diamcalc face up LR Crown and TABLE. Again logical( not mine) conclusion " Painted diamond is not good( best) . We need penalty such diamonds"
3) Continue work with parametrical model, Do longer start facets and see See diamcalc face up LR Crown and TABLE.
What is logical conclusion now?
Re: Rhino. I don't understand your last comment Serg because I stand in full agreement with everything you state here including your last comments regarding the stars in combination with the painting. It appears we are very much on the same page. My research into the GIA system regarding these issues also concurs.
Rhino,
1)Take standard diamond, Check different star facets( 40%, 50%,60%) . You will receive more or less same diamonds( same Brilliance, pattern is different of course. Much more easy to control diamcalc face up LR Crown and TABLE ). You can see it for other normal proportions too. Logical conclusion :" Stars facets in range 40-50% are not critical for cut grades"( It is not mine conclusion!, it is just Logical conclusion.)
2) to take parametrical painted diamond( or may be better pained diamond) with exactly same average parameters( like painted diamonds from your example, which model and photo you published on PS). See diamcalc face up LR Crown and TABLE. Again logical( not mine) conclusion " Painted diamond is not good( best) . We need penalty such diamonds"
3) Continue work with parametrical model, Do longer start facets and see See diamcalc face up LR Crown and TABLE.
What is logical conclusion now?
adamasgem
Brilliant_Rock
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- May 23, 2003
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Sergey.. I don't think anyone knows what the hell the GIA algorithm is about regarding painted girdles. Dana at Eightstar checked some of the LAST batch of Eightstars they had sent to GIA and only got VG's and G's for a cut grade, and irresponsible, stupid and arbitrary "decision" on GIA's part based on phoneyed up "science" As far as I know, they are using AGS now exclusively.
I think half the problems of painted girdles at GIA arose because of the troubles the Sarin machine had with measuring painted girdles, like we discussed a few months ago on a PS thread. I don't know if that is fixed. I somehow doubt it.
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The study of too much and too little painting and digging is very very complex.
With shallower stones I have seen a small amount of digging appears to improve the stone - on every steeper deeper stone it is very bad.
On slightly deep stones - i have seen many stones that seem to perform better with a little painting on either crown or pavilion - these are common in the market.
But for GIA to conduct this observer testing with Diamond dock and apply rules to a parametric system would be 2 or 5 times more difficulat than the original survey.
It would be almost as difficult as using this method to grade a princess or square emerald. (which is also next to impossible with gIA''s approach)
With shallower stones I have seen a small amount of digging appears to improve the stone - on every steeper deeper stone it is very bad.
On slightly deep stones - i have seen many stones that seem to perform better with a little painting on either crown or pavilion - these are common in the market.
But for GIA to conduct this observer testing with Diamond dock and apply rules to a parametric system would be 2 or 5 times more difficulat than the original survey.
It would be almost as difficult as using this method to grade a princess or square emerald. (which is also next to impossible with gIA''s approach)
Re: http://www.goodoldgold.com/4Cs/NewCutGrading/
Just read "New Cut Grading" section on new Rhino site. Very nice presented information. I sure most information from this section is very helpful for active consumers. My advise to read all section and be critical.
Just read "New Cut Grading" section on new Rhino site. Very nice presented information. I sure most information from this section is very helpful for active consumers. My advise to read all section and be critical.
It is not means what I support all conclusions from this sections. I think sometimes information can be misleading and conclusions wrong, but it is best common explanation for consumer which I read
Shay37
Ideal_Rock
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