More Details on Upcoming GIA Diamond Cut Grading System

[pricescope]

GIA: Institute Experts Give More Details on Upcoming GIA Diamond Cut Grading System

• GIA has developed and is currently beta testing online software and a comprehensive database to estimate the cut grade of round brilliant diamonds. The latter has been embedded in a number of leading optical measuring devices. These products will be available when GIA officially announces the launch date for its new diamond cut grading system.
• The online cut-grade estimation software will be available free of charge on the GIA website when it is released.
• The new system takes into account the following measured proportions: total depth, table size, average crown angle, average pavilion angle, average star length, and average lower-half/girdle length.

This is similar to HCA except average star length, and average lower-half/girdle length. Garry, how''s your pattent is doing?

 

[JohnQuixote]

GIA's version of HCA. This is no surprise to Garry. Seeing minor facets included is a step forward for this type of metric unless they're rounding up/down, which is the rumor.

GIA moves from no cut grading to proportions. AGS moves from proportions to performance-based.

There will be no lack of discussion here.

 

[Garry H (Cut Nut)]

This is a proportion of a GIA 'Excellent' from a Sarin recut calculation using GIA's embedded Beta software.

Of course this DiamCalc AGS score is AGS new cut proportion candidates in the new soon to be released DiamCalc that will blow you'al little minds with some amazing surprises

 

[Rhino]

Date: 7/16/2005 1:28:35 PM
Author: Garry H (Cut Nut)
This is a proportion of a GIA ''Excellent'' from a Sarin recut calculation using GIA''s embedded Beta software.

Of course this DiamCalc AGS score is AGS new cut proportion candidates in the new soon to be released DiamCalc that will blow you''al little minds with some amazing surprises

Which is to be released ... ?!?!?

Garry... you mean to tell me that qualifies as a GIA Grade1?

 

[kenny]

GIA excellent = AGS 4?

Was this a business decision on GIA's part to increase their business volume since there are more stones that are cut to this standard than cut to AGS 0's tighter specs?

Now the sellers and buyers of GIA excellent cuts can pretend they have the best possible cut?
I'm trying to read between the lines here.
Is this what is going on?

 

[Paul-Antwerp]

Date: 7/16/2005 1:28:35 PM
Author: Garry H (Cut Nut)
This is a proportion of a GIA ''Excellent'' from a Sarin recut calculation using GIA''s embedded Beta software.

Of course this DiamCalc AGS score is AGS new cut proportion candidates in the new soon to be released DiamCalc that will blow you''al little minds with some amazing surprises

Knowin Garry since a few years, I have learned that when he says little and only gives some hints, that is the time to pay extra attention. I will try to clarify.

Sarin and OGI have just introduced their new software-updates, which include the new GIA-system (in a beta-version, since it is not officially released yet).

If you measure a stone with one of these machines, you can perform a re-cut-function. Suppose that your stone is ''Very Good'' and you wish to know how to re-cut it to ''Excellent''. The machine will then give you the proportion-combination, which costs you the minimum of weight. In a sense, it will find you the heaviest possible GIA-Excellent.

Garry has put that proportion-combination into Diamcalc, in order to see idealscope, ASET, and other views of that GIA-Excellent stone. Apparently, he also has a beta-version of Diamcalc, which includes the ''cutting guidelines'' of AGS. In this way, he can show you that, if all is cut symmetrically, this GIA-Excellent-stone might score AGS-4 in the new system. Knowing that the AGS cutting guidelines are not the grading guidelines, it is not even sure that the stone will be AGS-4, it might even be graded lower.

Of course, this is just one example, and probably the worst possible, but you must be aware, that the majority of cutters will use their Sarins and OGI''s to cut for GIA-Excellent. The machines will always advise the heaviest possible combination, and a lot of the cutters will cut this. Just like one saw a lot of steep-deep-combo-old-AGS-0''s, because of this reason, one will see a lot of these AGS-4-GIA-Excellents.

I hope that this clarifies Garry''s post somewhat.

Live long,

 

[Dancing Fire]

Paul
how about the other way around.would all the new AGS 0 cut get a top GIA grade?

 

[Maxine]

So is the goal of GIA to improve the cut of stones or to loosen their standards????

 

[Garry H (Cut Nut)]

Paul has read between the lines very well. It is supposition at this stage, but one primary concern of the Cut Group, that I am part of, is that no cut grading system should give good grades to bad stones and vice a versa. If this is to be a stone that would recieve an excellent grade as the Sarin sales rep told me, then the Cut Group is concerned that all future releases of cut grade systems might be criticised.

AGS 0 stones with tables below 52% would not recieve GIA excellent as I currently understand it. AGS have no down side limit on table sizes: Peter Yantzer said - if someone can cut a beautiful (57 facet round) stone with a table size below 47% that qualifys for light return, spread etc, then we will grade it AGS 0. (good on him). That is paraphrased, not quoted.

But I can only find some rare examples of crown and pavilion combinations that might be outside GIA''s excellent.

Maxine "So is the goal of GIA to improve the cut of stones or to loosen their standards????

GIA is not loosening their standards. It is currently possible for an AGS 10 to get GIA Excellent Excellent.

 

[kenny]

Garry wrote "It is currently possible for an AGS 10 to get GIA Excellent Excellent. "

Oh great! This is more confusing than ever.
Clear as mud for us consumers.

So I guess I now if I seek the best cut I have to compare an AGS 0 and a GIA Excellent Excellet side by side (like I would an 8-Star and a Solasfera and Super H+A) and just decide which "look" I prefer?

I was hoping these labs were moving towards something more scientific and less subjective.

 

[Maxine]

Date: 7/17/2005 2:18:49 PM
Author: kenny
Garry wrote ''It is currently possible for an AGS 10 to get GIA Excellent Excellent. ''

Oh great! This is more confusing than ever.
Clear as mud for us consumers.

So I guess I now if I seek the best cut I have to compare an AGS 0 and a GIA Excellent Excellet side by side (like I would an 8-Star and a Solasfera and Super H+A) and just decide which ''look'' I prefer?

I was hoping these labs were moving towards something more scientific and less subjective.

....and more consistent......!

 

[strmrdr]

Date: 7/17/2005 2:32:27 PM
Author: Maxine

Date: 7/17/2005 2:18:49 PM

Author: kenny

Garry wrote ''It is currently possible for an AGS 10 to get GIA Excellent Excellent. ''


Oh great! This is more confusing than ever.

Clear as mud for us consumers.


So I guess I now if I seek the best cut I have to compare an AGS 0 and a GIA Excellent Excellet side by side (like I would an 8-Star and a Solasfera and Super H+A) and just decide which ''look'' I prefer?


I was hoping these labs were moving towards something more scientific and less subjective.

....and more consistent......!

AGS has done that.
GIA in a me too effort hasn''t.

GIA in order to not make the top grade narrow and lose business has widened it beyond usefulness from what Iv seen so far.

AGS has said this is how to cut them just do it.
Because of the reputation and the price premium AGS0 diamonds get they can get by with it.

 

[Paul-Antwerp]

Talking about reading between the lines, how about this:

The article says the following:

"GIA Education course material will contain information on the GIA Diamond Cut Grading System starting in the first quarter of 2006. "

and

"GIA will not issue the new reports until several months after the official announcement of its cut-grading system, so the trade can learn about and adjust to the new system."

If I understand both statements well, then I foresee the launch of new GIA-reports at the earliest around halfway 2006. If it is later than June 2006, then, it will only be for 2007, since they will not want to disrupt the Christmas-season of 2006.

If there is sufficient resistance to the beta-testing now, and to the initial announcements, then it can well be that the new system will end up in the freezer again. I would not be surprised.

Live long,

 

[mkb]

Paul and Gary,
I see what you mean by: this is the right place to start (getting informed).
Very interesting, thanks

luc

 

[pricescope]

Luc, welcome to the forum