GCAL on a Gabrielle

[winks]

Good day all!

First off, i''d like to say a big hello to everyone there!

I''m interested in this stone and would like to seek others'' opinion on the GCAL report.

Go to Gemfacts: http://www.gemfacts.com/Cert/

and key in certificate number 182980159

It''s a Gabrielle, but i''ve only known DPL to do the grading here. Just wondering how GCAL and DPL compare to each other...even though it''s a question that may not get a perfect answer!

Paul

 

[Garry H (Cut Nut)]

Date: 1/15/2010 11:47:43 PM
Author:winks
Good day all!

First off, i''d like to say a big hello to everyone there!

I''m interested in this stone and would like to seek others'' opinion on the GCAL report.

Go to Gemfacts: http://www.gemfacts.com/Cert/

and key in certificate number 182980159

It''s a Gabrielle, but i''ve only known DPL to do the grading here. Just wondering how GCAL and DPL compare to each other...even though it''s a question that may not get a perfect answer!

Paul

I have never found out exactly how to understand their color coded system Paul - but from what I think I know that looks quite good.

 

[Stephan]

It should be nice, but why didn''t you buy a H&A?
It would have much better spread.

 

[denverappraiser]

Paul,

I’m with Garry in that I’ve never heard a decent explanation of what the GCAL color system does and does not show but the origins of GCAL include purchasing DPL early on and they are using the same system or at least something derived from it.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[winks]

Thank you so much for your comments Gary, Stephen and Neil, it''s always comforting to hear the opinions of the more experienced!

First off, apologies for my late reply... I sail quite a bit and have only just returned. Don''t get the internet when I''m out there.. heh.

I don''t get the colour grading system either, but as a seaman, i can kinda draw a parallel with how charts and maps use different colours for contour lines I suppose. Gimmick or not, I certainly can''t tell but the stone itself seems pretty good.

Indeed I was considering an H&A stone - the market here in Singapore is full of them!!! - but 2 factors swayed in favour of the Gabrielle: firstly, I was more concerned with the scintilation and while the H&A looks good through a scope, i wanted something that looked good on a finger. Secondly, the girlfriend prefers the Gabrielle...

I have another noob question though...I put the dimensions through the HCA scoring system and it gave a rather poor grading of the stone. i''m assuming that the HCA program deals with ideal cut round stones and that whatever algorithm it uses does not allply to the Gabrielle''s - though round too - fancy cut?

Paul

 

[stone-cold11]

yap, HCA is calibrated for the standard 57 facets round cut, not the special cuts, so no point checking with it.

 

[winks]

Yep, I think I kinda answered my own question. wahaha...

Hmm..mebbe the HCA could be used for other cuts in the future eh? Gary?

Paul

 

[stone-cold11]

No point really, not enough demand for it.

 

[Lorelei]

Date: 1/24/2010 7:50:55 AM
Author: winks
Thank you so much for your comments Gary, Stephen and Neil, it''s always comforting to hear the opinions of the more experienced!

First off, apologies for my late reply... I sail quite a bit and have only just returned. Don''t get the internet when I''m out there.. heh.

I don''t get the colour grading system either, but as a seaman, i can kinda draw a parallel with how charts and maps use different colours for contour lines I suppose. Gimmick or not, I certainly can''t tell but the stone itself seems pretty good.

Indeed I was considering an H&A stone - the market here in Singapore is full of them!!! - but 2 factors swayed in favour of the Gabrielle: firstly, I was more concerned with the scintilation and while the H&A looks good through a scope, i wanted something that looked good on a finger. Secondly, the girlfriend prefers the Gabrielle

...

I have another noob question though...I put the dimensions through the HCA scoring system and it gave a rather poor grading of the stone. i''m assuming that the HCA program deals with ideal cut round stones and that whatever algorithm it uses does not allply to the Gabrielle''s - though round too - fancy cut?

Paul

Hi Paul,

I think you have your answer!

 

[30yearsofdiamonds]

I was with GCAL for three years and most likely graded or checked the grading on that stone, not that I would remember. What I can tell you was that almost every Gabrielle was extremely well cut in both polish and symmetry, especially for such a difficult stone to cut perfectly. I saw many while I was there.

Now for the Optical Symmetry Analysis explanation;

All that the colors are indicating when the color patterns are evenly distributed throughout is an evenness of light return. That is a result of an excellent visual symmetry, i.e facet shapes, roundness and alignment. It also is a result of a well proportioned stone since an off center culet or poor pavilion angles, crown angles etc will return less light and thus will not show all the colors, display uneven patterns of colors,or there will be white areas, for lesser makes. They use four colors that are concentric inside a dome, green, red, black and blue.

Dan

EngagementRingsDirect

 

[Garry H (Cut Nut)]

Date: 1/24/2010 12:40:52 PM
Author: 30yearsofdiamonds


Now for the Optical Symmetry Analysis explanation;

All that the colors are indicating when the color patterns are evenly distributed throughout is an evenness of light return. That is a result of an excellent visual symmetry, i.e facet shapes, roundness and alignment. It also is a result of a well proportioned stone since an off center culet or poor pavilion angles, crown angles etc will return less light and thus will not show all the colors, display uneven patterns of colors,or there will be white areas, for lesser makes. They use four colors that are concentric inside a dome, green, red, black and blue.

Dan

EngagementRingsDirect

Hi Dan,
thanks for the explanation.
I went back to their site and dug around and found a new graphic
http://www.diamondid.com/pages/KNOW_YOUR_DIAMOND/DIAMOND_QUALITY/DIAMOND_QUALITY_CUT.html

So this is new and the first time I have seen it.
I have tried in the past to model the lighting based on images, but failed because it would appear the source of colored light is not consistantly placed over the stone.
It is also evident from their description that they view this as a symmetry device only, rather than a light return feature. their other divice shows light leakage, which is pretty much a waste of time (see various current threads). e.g https://www.pricescope.com/community/threads/is-the-internet-and-cut-grading-the-enemy-of-creativity-in-cutting.133907/page-4

I do not understand why the Palmieri family have been so secretive about this simple system. If it is inconsistent in application, then surely we can easily help them iron out any bugs. Consiracy theorists might conclude that Big Brother BN might prefer the system remained opaque?

 

[winks]

While Lorelei put it best, I must say that this thread has provided so much more than what I was initially asking.

As a symmetry device, and i speak as a noob buyer, it does it''s job well in perhaps convincing a greater market no? And as such, it serves it purpose.

Can I inquire as to what you mean with regards to the inconsistency issue Greg?

 

[Garry H (Cut Nut)]

Date: 1/25/2010 12:48:00 PM
Author: winks
While Lorelei put it best, I must say that this thread has provided so much more than what I was initially asking.

As a symmetry device, and i speak as a noob buyer, it does it''s job well in perhaps convincing a greater market no? And as such, it serves it purpose.

Can I inquire as to what you mean with regards to the inconsistency issue Greg? Greg or Garry?

As a symmetry device the images are far too small.
Have you seen the reports?
Here is one.
When you print it comes out less than 10mm
The sample guideline images are even smaller.