GCAL 4X 0's vs AGS 4X 0's

[celledge]

Assuming the angles fit in super ideal proportions according to WF, BG, Tolkowsky, etc anyone have opinions on a diamond with GCAL 4x Excellent Cert vs AGS 4x Ideal Cert?

 

[DejaWiz]

As long as the light assessment shakes out for both and the color and clarity grades seem accurate, then either would make me comfortable.
What are your own thoughts about them?

 

[Karl_K]

Interesting question, the GCAL 8x report is a pretty compelling report. For lab/mmd its my favorite report.
The biggest problem with it is that all the tests are closed source, some are easy to reverse engineer others not so much.
I have a huge problem giving some of the tests much weight because they are so closed.
The plus is that it has a lot of actual images on it including h&a.
The reports I have seen for stones that also had other reports showed the color and clarity was ballpark with the others for the most part.

However the AGSL reports have a proven track record of trust so for high cost diamonds I would strongly lean towards AGSL with supplemental images for h&a.
Or a combination of AGSL and GCAL 8x reports for the same stone but if going duel reports I would lean more towards a combo of GIA and GCAL 8x.
GIA for color and clarity and the GCAL report to provide some images and cut information.

 

[Victor Canera]

I’d agree with Karl in that AGSL’s methodology has been pretty transparent and their research has been peer reviewed and accepted in general by the industry. Other laboratory’s not as much.

The number of analytic imagery provided on GCAL’s 4X cert is definitely a step in the right direction though. There are some labs that provide stock hearts scope imagery on their man made diamond reports for example which are not of the actual diamond. This leads to confusion with the consumer into thinking those are the actual diamond’s imagery and that it’s a hearts & arrows diamond.

Good luck!

 

[Texas Leaguer]

Interesting question, the GCAL 8x report is a pretty compelling report. For lab/mmd its my favorite report.
The biggest problem with it is that all the tests are closed source, some are easy to reverse engineer others not so much.
I have a huge problem giving some of the tests much weight because they are so closed.
The plus is that it has a lot of actual images on it including h&a.
The reports I have seen for stones that also had other reports showed the color and clarity was ballpark with the others for the most part.

However the AGSL reports have a proven track record of trust so for high cost diamonds I would strongly lean towards AGSL with supplemental images for h&a.
Or a combination of AGSL and GCAL 8x reports for the same stone but if going duel reports I would lean more towards a combo of GIA and GCAL 8x.
GIA for color and clarity and the GCAL report to provide some images and cut information.

General agreement here. GCAL seems to have taken a pretty big step in the direction of cut grade analysis, which is a welcome development. They are bringing together a very comprehensive package of information.

However, it does seem like there is a little 'more is more' philosophy going into it. For example, most of us normally think of 3D symmetry being illustrated quite well by an H&A image. They have split that into two aspects/images including the one that looks suspiciously like ASET (a patentented technology).

What they call "optical brilliance" appears to simply be brightness (overall light return). Most discussions around brilliance require recognizing the contribution made by dynamic contrast. GCAL analyzes scintillation separately, and to your point @Karl_K , there is no way to know how they value scintillation - e.g. smaller, quicker sparkles, larger longer sparkles, an optimized combination? This is an aspect of flavor or taste that has perplexed researchers looking to apply objective grades to it. While AGS measures contrast and will penalize for too much or two little, they have intentionally avoided grading scintillation as a separate LP aspect.

Overall, I think the GCAL reporting covers a lot of bases and creates a lot of value for the consumer. It's important to note that they are using their approach to grade some fancies as well (oval and princess). This is simply not possible to do in a parameter-based system such as GIA uses.

 

[Karl_K]

They have split that into two aspects/images including the one that looks suspiciously like ASET (a patentented technology).

I complained on here about the confusion between the GCAL scope and ASET and was informed by @Garry H (Cut Nut) as I recall that the GCAL scope and patent existed for years before the ASET scope was introduced.

 

[Mlh]

I know that this thread is about Gcal and Ags but can someone shed light on how IGI determines which stones warrant the H&A report?

 

[DejaWiz]

I know that this thread is about Gcal and Ags but can someone shed light on how IGI determines which stones warrant the H&A report?

Here's a nifty little e-brochure about it (downloadable):

School Of Gemology

IGI's School of Gemology offers rough diamond grading to gemstones, pearls, modern treatments and computer-assisted jewelry design courses.

www.igi.org

 

[Karl_K]

I do not consider the igi, or anyone else's claim of h&a valid unless actual h&a images are provided it is not h&a. (IS or ASET images can be used as the arrow image)

 

[DejaWiz]

I do not consider the igi, or anyone else's claim of h&a valid unless actual h&a images are provided it is not h&a. (IS or ASET images can be used as the arrow image)

That's my thoughts...if any lab is stating H&A, then they must be using the appropriate tools to check and verify H&A, so why not just put the actual H&A images on the report? It would provide so much value-add to both the seller and the buyer, I would think.

 

[Mlh]

Thanks for weighing in @Karl_K , @DejaWiz ! So do you think that IGI does actually evaluate the H&A stones with the H&A viewer?

 

[DejaWiz]

Thanks for weighing in @Karl_K , @DejaWiz ! So do you think that IGI does actually evaluate the H&A stones with the H&A viewer?

No idea. They don't specifically mention if a H&A viewer is used...they only have basic info about H&A and the viewer:

Hearts & Arrows Report

Hearts & Arrows (H&A) diamonds are cut so precisely that their facet reflections overlap when viewed in a reflective scope.

www.igi.org

 

[Mlh]

No idea. They don't specifically mention if a H&A viewer is used...they only have basic info about H&A and the viewer:

Hearts & Arrows Report

Hearts & Arrows (H&A) diamonds are cut so precisely that their facet reflections overlap when viewed in a reflective scope.

www.igi.org

Thanks @DejaWiz ! I couldn't find any information either.

 

[John Pollard]

No idea. They don't specifically mention if a H&A viewer is used...they only have basic info about H&A and the viewer:

Hello,

@Mlh and @DejaWiz - Yes. When diamonds are submitted for a H&A report IGI graders use hearts & arrows viewers, along with established grading guidelines, to determine whether the diamond submitted qualifies for that report format.

I do not consider the igi, or anyone else's claim of h&a valid unless actual h&a images are provided it is not h&a.

IGI introduced the H&A report in overseas markets more than 25 years ago. At the time the vast majority of diamond sales were made in stores. There was no need to take images since anyone selling them would have a H&A viewer at the counter. That was the whole 'sizzle' of H&A. "Look in this viewer" "Oh Wow! Cool!" It remains so to this day. There's no substitute for seeing those patterns live, in 3D.

Imprints (stock H&A icons) were applied to H&A reports to differentiate them from normal reports - the same way lab grown diamond reports have a yellow cover to visibly separate them from natural diamond reports.

After the turn of the century diamonds were increasingly sold online. As the number of sellers offering H&A online increased, primarily in overseas markets, IGI added the option to have actual images added to the H&A report. Logically, for an additional cost. That service continues to be offered today.

 

[Victor Canera]

Hello,

@Mlh and @DejaWiz - Yes. When diamonds are submitted for a H&A report IGI graders use hearts & arrows viewers, along with established grading guidelines, to determine whether the diamond submitted qualifies for that report format.



IGI introduced the H&A report in overseas markets more than 25 years ago. At the time the vast majority of diamond sales were made in stores. There was no need to take images since anyone selling them would have a H&A viewer at the counter. That was the whole 'sizzle' of H&A. "Look in this viewer" "Oh Wow! Cool!" It remains so to this day. There's no substitute for seeing those patterns live, in 3D.

Imprints (stock H&A icons) were applied to H&A reports to differentiate them from normal reports - the same way lab grown diamond reports have a yellow cover to visibly separate them from natural diamond reports.

After the turn of the century diamonds were increasingly sold online. As the number of sellers offering H&A online increased, primarily in overseas markets, IGI added the option to have actual images added to the H&A report. Logically, for an additional cost. That service continues to be offered today.

Thanks for the information John. To clarify though, the hearts and arrows images used on these IGI reports are not of the actual diamond though are they? This creates confusion in the marketplace IMHO.

 

[Victor Canera]

I do not consider the igi, or anyone else's claim of h&a valid unless actual h&a images are provided it is not h&a. (IS or ASET images can be used as the arrow image)

My feelings exactly Karl.

 

[John Pollard]

Thanks for the information John. To clarify though, the hearts and arrows images used on these IGI reports are not of the actual diamond though are they?

Actual is actual. As stated above, when the number of sellers offering H&A online increased IGI added the option to have the diamond's actual H&A images added to the report for an additional cost.

We do this for a number of overseas H&A brands, including CSS' H&A line in China.

 

[Mlh]

Actual is actual. As stated above, when the number of sellers offering H&A online increased IGI added the option to have the diamond's actual H&A images added to the report for an additional cost.

We do this for a number of overseas H&A brands, including CSS' H&A line in China.

Thanks so much for the explanation @John Pollard ! So if someone submits a diamond and pays for an upgraded h@a report they can request the actual image be put on the report? If they don't want to pay extra for that then the stock image is put on the report? Do I have that right?

 

[Kim N]

John Pollard--this, for example, is a stock image, is that correct? So a buyer would have to pay the additional cost to have the actual H&A images on their report?

Verify Your Report

Ensure authenticity & accuracy of your report here. Verify your gemstone report online for complete confidence in your precious investments.

www.igi.org

 

[John Pollard]

John Pollard--this, for example, is a stock image, is that correct? So a buyer would have to pay the additional cost to have the actual H&A images on their report?

Verify Your Report

Ensure authenticity & accuracy of your report here. Verify your gemstone report online for complete confidence in your precious investments.

www.igi.org

Correct, although that is not an image, it's a logo/icon. It differentiates the H&A report from a normal reports when a jeweler is showing the stone.

The producer or retailer who submits the diamonds chooses whether or not the report will include actual H&A images.

 

[Texas Leaguer]

I complained on here about the confusion between the GCAL scope and ASET and was informed by @Garry H (Cut Nut) as I recall that the GCAL scope and patent existed for years before the ASET scope was introduced.

I don't see any evidence of that. No mention of patent in their online literature or on the report. GCAL acquired Gemprint, a patented technology, and that is clearly called out. But no other mentions of patents that I have found.