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Gia - Excellent Cut Grade


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#1 isplash

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Posted 06 February 2007 - 10:05 AM

Hi everyone. ;)

this is my first post in the forum.
I have recently bought a proposal ring for my gf.
Is not a big one though, it carat weight is 0.36
but what i love about this diamond is
GIA
Cut Grade - Excellent
Symmetry - Excellent
Polish - Very Good
Clarity grade - VS1, characteristics - Cloud

i have some doubt hope the expert here can advise.
since the cut grade and symmetry are excellent, does it means that this is a Heart and Arrow diamond?

As for the Clarity characteristics, one would prefer feather, pinpoint or cloud?

TIA! ;>

#2 denverappraiser

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Posted 06 February 2007 - 06:44 PM

Hearts & Arrows is a special pattern that is part of symmetry. Most H&A’s are GIA excellent cuts but it’s not necessary. They aren’t looking at the same things. The way to tell if it’s an H&A is to inspect the stone from the top and bottom with a special viewer that the jewelers have for this purpose. They’ll know already because they will be touting it as one of the reasons to buy a particular stone and part of the justification for a higher price.

A VS1 will have no inclusions that affect either the durability or beauty of the stone. The details of the inclusion is of purely academic interest at that level.

Neil
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#3 isplash

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Posted 07 February 2007 - 06:52 AM

Thanks Neil. : )

so even a stone cut in a conventional way with a excellent symmetry/cut is not necessary a H&A..
hmm, i always got misled by the sales pple in the store, they always tell me that stone that are grade as
excellent/ideal in symmetry and excellent/ideal in cut are H&A be it a GIA or AGS.

Dias

#4 denverappraiser

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Posted 07 February 2007 - 07:44 AM

Correct.

GIA doesn't grade stones ideal but their 'excellent' cut grade indicates some specific proportion sets that were popular when they did a big study of a few hundred thousand observations with different stones, different viewers, different lighting, etc. AGS-Ideal means that a 3d model of the stone when run through their raytracing program indicates that the stone has a good optical performance. Both labs also include a personal inspection by an experienced gemologist for polish and symmetry. They are completely different both from each other and from the hearts and arrows pattern.

In practice, most H&A stones would qualify as GIA-excellent as well but this has more to do with economics than optics. H&A doesn't just happen, cutters work extra to get it and they do it because they want to charge a premium price for the finished product. H&A customers tend to be fairly picky and an H&A with a 'good' cut would be tough to sell unless they sell at a steep discount, which sort of defeats the point of doing all of that extra work.

Neil

Edited by denverappraiser, 08 February 2007 - 06:16 AM.

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#5 diamondsonfifth.com

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Posted 18 February 2007 - 12:31 PM

What a lot of jewelers say that a big portion of GIA or AGS excellent/ideal in symmetry and excellent/ideal in cut are automatically H&A.

#6 denverappraiser

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Posted 19 February 2007 - 10:43 AM

What a lot of jewelers say that a big portion of GIA or AGS excellent/ideal in symmetry and excellent/ideal in cut are automatically H&A.


I agree that a lot of people say it, but that doesn't make it accurate. Most round H&A's are excellent/ideal. The reverse is not the case. Customers interested in H&A patterning should not make this assumption.

Neil
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#7 H and A

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Posted 19 February 2007 - 11:56 AM

Blue Nile says all of their GIA graded excellent cut diamonds show hearts and arrows, and they've got thousands of them from many different cutters. True enough, when I bought my GIA graded excellent cut diamond from them it showed very good hearts and arrows through a viewer I bought. And from what I understand, AGS has worked very closely with Eightstar (the original H & A marketers) in some of their cut grading schemes, using Eightstar proportions as their benchmark for ideal. An AGS 0 diamond should almost always show hearts and arrows from what I understand. I hope this helps!

Denverappraiser, how many GIA excellent or AGS 0 cut graded diamonds have you come across that didn't shows hearts and arrows?

#8 denverappraiser

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Posted 19 February 2007 - 01:14 PM

I see at least a dozen GIA-excellent stones every week and have done so since they hve become available. Most of them do not show well formed hearts and arrows. The ones that do tend to be specifically marketed as such, and even some of those don’t. If I was to apply the same patterning standards as eightstar (which they get from the Central Gem Lab in Japan by the way), I would guess that I see fewer than one a week that DOES have it.

AGS does not grade hearts & arrows and it is not one of the criteria for AGS-0 cut grading.

Neil

Edited by denverappraiser, 19 February 2007 - 01:42 PM.

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#9 H and A

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Posted 19 February 2007 - 02:07 PM

I see at least a dozen GIA-excellent stones every week and have done so since they hve become available. Most of them do not show well formed hearts and arrows. The ones that do tend to be specifically marketed as such, and even some of those don’t. If I was to apply the same patterning standards as eightstar (which they get from the Central Gem Lab in Japan by the way), I would guess that I see fewer than one a week that DOES have it.

AGS does not grade hearts & arrows and it is not one of the criteria for AGS-0 cut grading.

Neil

Wow, that's very interesting to hear. And somewhat confusing based on my (admittedly limited) experience. I know since hearts and arrows have become so popular both as a cutting style and a marketing tool, some people are trying to say if it aint' crisp and perfectly symmetrical hearts and arrows it shouldn't be called hearts and arrows at all. Like Whiteflash, for example:
Posted Image
They want to say the one on the right shouldn't be considered a true hearts and arrows cut stone. Do you agree? Should the hearts and arrows patterns be perfect to be considered hearts and arrows? Because from what I understand these days most GIA excellent and almost all AGS 0 stones will at least look similar to the one on the right although maybe not a perfect pattern like the one on the left.

Edited by H and A, 19 February 2007 - 02:19 PM.


#10 denverappraiser

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Posted 19 February 2007 - 03:04 PM

Here's an example of a stone I recently saw that I would NOT describe as hearts. The seller did.

Posted Image

Neil
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#11 H and A

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Posted 19 February 2007 - 03:32 PM

Here's an example of a stone I recently saw that I would NOT describe as hearts. The seller did.

Ah, that's kind of what I assumed was going on here. Everybody's definition of hearts and arrows seems to be a little different... some say it has to be very crisp and perfect, some say it has to be somewhat crisp and perfect, while others just need to see some resemblence of a hearts and arrows patterning...

There is no industry standard, which is why some people are saying GIA excellent and AGS 0 cut graded diamonds almost always show hearts and arrows, and some people are saying they rarely show hearts and arrows. I fear that the seller's definition and the buyers definition may not always match up. To me you can clearly see a pattern of hearts in the above picture you posted, but to you it's not good enough.

To me, this would not be considered a hearts and arrows diamond because there's obviously no hearts or arrows patterning:
Posted ImagePosted Image
Of course you will not see something like this in an AGS 0 or GIA Excellent cut graded diamond from what I understand.

Edited by H and A, 19 February 2007 - 04:04 PM.


#12 denverappraiser

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Posted 19 February 2007 - 04:36 PM

Of course you will not see something like this in an AGS 0 or GIA Excellent cut graded diamond from what I understand.


I agree that the problem is a lack of standards of what 'hearts and arrows' means.
This is a GIA excellent from one of my color masters. AGS would probably call this a 2.
It's really a very nice looking stone by the way.

Posted Image

Neil

Edited by denverappraiser, 19 February 2007 - 04:38 PM.

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#13 Diamondssz

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Posted 07 February 2010 - 07:57 AM

Of course you will not see something like this in an AGS 0 or GIA Excellent cut graded diamond from what I understand.


I agree that the problem is a lack of standards of what 'hearts and arrows' means.
This is a GIA excellent from one of my color masters. AGS would probably call this a 2.
It's really a very nice looking stone by the way.

Posted Image

Neil


Hi, denverappraiser

We've recently bought a GIA certified 3x excellents diamond. with note of "H&A:. This is of a E, IF quality. When i was walking into a tiffany shop and tried on one of their ring of D & SI, the new ring we bought did not shine as much. Even when compared with an I Colour ones, our ring was alot whiter but still did not shine. It felt like the top was covered by mist film. I am some what worried by this and drawn to 2 conclusions:

1) I may have been using quite a lot of hand cream, which results in the diamond not shining, is there a way of cleaning the diamond to make it shine or

2) I need to recheck this diamond which i am pretty we did try to look for the numbering inscription on the diamond matching the certificate.

Any suggestions please. I apologise in not writing this on a new post but this is a close topic to H&A.

Thanks heaps. :)

#14 davidelevi

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Posted 07 February 2010 - 08:29 AM

I'm not Neil, but... it's most likely because your ring is dirty. Diamonds are chemically speaking "grease magnets" (in fact one of the ways of separating diamonds from other stones in alluvial deposits exploits this fact!).

Try the following:

Warm water + a little dish soap + a soft bristled toothbrush. Give the diamond a good wash, then rinse in running water with a last dip in gin or vodka (or rubbing alcohol). Then go back into Tiffany's and compare again. And remove the ring when putting on hands lotion :)
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#15 denverappraiser

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Posted 07 February 2010 - 10:57 AM

I would add to Davide’s comment that the most likely place for crud buildup is on the BACK of the stone, not the front. This kills the life just as fast. When you clean it, pay special attention to the areas between the prongs and on the pavilion side of the stone. You can bet that the stones Tiffany are selling are squeaky clean in the store so it’s only a fair comparison if yours is as well. Color and clarity don’t have much to do with the sparkle of a diamond but a GIA/xxx should face up just fine compared to ANYTHING in the store if it’s clean and undamaged. Often stores have high powered steam cleaners that they’ll use for free although at least at the Tiffany in Denver they won’t do this for things they didn’t sell (the guys down the hall are much more cooperative).

A notation of ‘H&A’ on the GIA report is referring to a girdle inscription. People can write whatever they want on the girdle and GIA will report that it's there but they are not attesting to anything about it. H&A is not a term they use in their grading. Your stone may indeed be a hearts and arrows, by whatever definition you choose to use, but the GIA report isn’t evidence either way and although this has an affect on the patterning you see in the stone, it’s not related to the brilliance you are seeing in the store.

Neil
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#16 skip2myfoo

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Posted 08 February 2010 - 03:52 AM

I agree that the problem is a lack of standards of what 'hearts and arrows' means.
This is a GIA excellent from one of my color masters. AGS would probably call this a 2.
It's really a very nice looking stone by the way.

Posted Image

Neil



Hi, don't mean to hijack the thread...just wanna pick Neil's brains a lil if he doesn't mind! =D

I've read the little tutorial over at goodoldgold.com where they spoke of painted girdles (or was it dug out girdles) causing an AGS-0 to look inferior, in the eyes of an observer, to a GIA-excellent (except when looked under the hi-tech scans n stuff of course...which is the basis of AGS' grading scheme yes?)
Neil, which grading scale would you prefer - in terms of consistently (relatively) identifying diamonds with a great sparkle?

Also, WRT the diamond in the pic above, I'm not sure I see what you see; are you saying that its not a true H&A becos the "hearts" along the bottom half don't comprise of symmetrical halves?

Thanx for the help....and may I say that this is one awesome, informative forum!

#17 denverappraiser

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Posted 08 February 2010 - 04:47 AM

‘Painting ‘ and ‘digging’ refer to the rotation of the upper and lower girdle facets. These are the 16 small triangular facets around the outside edge of the stone on the crown and pavilion side. Because this is a 3 dimensional object, every facet has both an angle and an azimuth. As an example, hold your hand flat with palm down at an angle to the floor, sort of like a Nazi salute. The angle between your palm and the floor is the facet angle. Now rotate your wrist without changing the angle. That’s the azimuth. In diamond terms, one direction is called painting and the opposite direction is called digging. Note that this is an attribute that doesn’t appear on any of the lab reports.

The usual reason this is done is in order to bring up the weight of the stone while retaining the angles and therefore retaining the eligibility for the various cut grades. It’s also done to serve as a focusing lens to bring more light towards the central axis of the stone which makes things brighter when viewed from that direction and make things look better in reflector viewers like ASET, Idealscope and H&A viewers. This isn’t necessarily bad and a lot of people really like the effect. It’s common in stones being marketed as super-ideal although it's not universal and, again, not necessarily bad. Both labs look for it when they inspect a stone and both labs have a certain tolerance for it within their top grades. In neither case is it included on their reports (which is why it sounds like a conspiracy and why it's a topic of concern among Internet shoppers). AGS does accept a little more of it than GIA does in their top grade.

Both labs assign their cut grades by taking a 3-D scan of the stone, creating a computer model of it and then doing analysis on that model. In neither case are they evaluating the stone directly and in neither case is the analysis done by humans. Both also have an expert gemologist inspect the symmetry and polish and the final cut grade incorporates all 3 of those factors.

Personally I prefer the AGS system. It has a considerably better scientific footing and it’s far more specific in exactly what you can expect if you’re buying one. This is also it’s biggest criticism. The range of GIA-excellent is considerably bigger and it better reflects the reality that not everyone agrees on what makes for the most beautiful stone and ‘What is beautiful?’ is not a scientific question. In the end, it’s not the lab that makes one stone better than another, it’s the cutter, and it’s up to the buyer to decide which one sings to YOU. The lab grade is a guide and an opinion, nothing more.

In the above picture the hearts are not well formed, nor are the ‘V ’shapes at the center.

Neil

Edited by denverappraiser, 08 February 2010 - 09:12 AM.

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#18 slice4e

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Posted 06 April 2010 - 06:30 PM

Neal,


I am still in a little bit of a confusion about the H&A business. Here is my dilema: In one store, there is an EGL certified G-color, VVS1, Excellent Ideal Cut with H&A. I looked through the device and I was able to see perfect hearts & arrows - I was impressed.

In the other store, I have an GIA certified F-color, VS1. In the document, the cut is not rated, but on symmetry it sais excellet. Also in that store they did not have that tool so I can look for H&A.
Both stones are 0.5 carat.

So I have multiple questions. On one hand, I hear that GIA are more strict and thus I am a little scared buy the diamond that is certified by EGL, since it may not match the color or clarity. On the other hand, I know that the EGL stone has a perfect cut since it shows perfect hearts and arrows. The other stone, just sais excellent symmetry, but is that enough for me to know that the cut is just as good as the H&A one.


‘Painting ‘ and ‘digging’ refer to the rotation of the upper and lower girdle facets. These are the 16 small triangular facets around the outside edge of the stone on the crown and pavilion side. Because this is a 3 dimensional object, every facet has both an angle and an azimuth. As an example, hold your hand flat with palm down at an angle to the floor, sort of like a Nazi salute. The angle between your palm and the floor is the facet angle. Now rotate your wrist without changing the angle. That’s the azimuth. In diamond terms, one direction is called painting and the opposite direction is called digging. Note that this is an attribute that doesn’t appear on any of the lab reports.

The usual reason this is done is in order to bring up the weight of the stone while retaining the angles and therefore retaining the eligibility for the various cut grades. It’s also done to serve as a focusing lens to bring more light towards the central axis of the stone which makes things brighter when viewed from that direction and make things look better in reflector viewers like ASET, Idealscope and H&A viewers. This isn’t necessarily bad and a lot of people really like the effect. It’s common in stones being marketed as super-ideal although it's not universal and, again, not necessarily bad. Both labs look for it when they inspect a stone and both labs have a certain tolerance for it within their top grades. In neither case is it included on their reports (which is why it sounds like a conspiracy and why it's a topic of concern among Internet shoppers). AGS does accept a little more of it than GIA does in their top grade.

Both labs assign their cut grades by taking a 3-D scan of the stone, creating a computer model of it and then doing analysis on that model. In neither case are they evaluating the stone directly and in neither case is the analysis done by humans. Both also have an expert gemologist inspect the symmetry and polish and the final cut grade incorporates all 3 of those factors.

Personally I prefer the AGS system. It has a considerably better scientific footing and it’s far more specific in exactly what you can expect if you’re buying one. This is also it’s biggest criticism. The range of GIA-excellent is considerably bigger and it better reflects the reality that not everyone agrees on what makes for the most beautiful stone and ‘What is beautiful?’ is not a scientific question. In the end, it’s not the lab that makes one stone better than another, it’s the cutter, and it’s up to the buyer to decide which one sings to YOU. The lab grade is a guide and an opinion, nothing more.

In the above picture the hearts are not well formed, nor are the ‘V ’shapes at the center.

Neil



#19 denverappraiser

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Posted 07 April 2010 - 03:38 AM

Cut grading, symmetry grading and H&A are 3 different things that you’re lumping into one. EGL uses the terms ‘ideal’ and ‘hearts and arrows’ rather broadly and GIA doesn’t use them at all. What they are referring to when they call a stone ‘excellent’ in symmetry is that the table is in the center, that the crown and pavilion mains line up at the girdle, that the two sides are mirror images of each other if you made an imaginary split through the center etc. Excellent symmetry is required in order to get the H&A effect but it doesn’t cause it. That is to say, you can have excellent symmetry without H&A but you can’t have H&A without excellent symmetry.

GIA didn’t assign a cut grade prior to 2006 and they still only assign it on modern round brilliant cut stones. I’m guessing from your questions that you have a pre-2006 stone. That doesn’t mean that it’s not an excellent cut as well, but I agree it’s a bad sign. If it was, I think it’s decently likely that the dealer (or their supplier) would have submitted it for an update during the intervening 4 years in order to get the pedigree.

‘Perfect’ cut is a tricky thing to define, rather like defining what makes for a ‘perfect’ painting. Is it the one that looks the most like a photograph or something else entirely? Maximizing the look in the H&A scope, the idealscope, the ASET, the brilliancescope or any other such tool is a reasonable enough thing to do in it’s own context but be careful when you take the leap to define that as perfection.

Neil
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#20 davidelevi

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Posted 07 April 2010 - 12:32 PM

Perhaps you can resolve your dilemma in a much less intellectual way. Did you like one stone more than the other? Are they fairly priced and within your budget? If so, go for the one you like!
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