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Why don't online sites include cut in GIA listed diamonds

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alfsong

Rough_Rock
Joined
Jun 27, 2014
Messages
7
Hi All -
New to PS and so far - love it! Have been looking at diamonds online on PS vendor list and wondering why vendors like JA and WF don't tell you the quality of cut of their GIA diamonds. Important info and I don't understand why they don't list it, since GIA certainly includes it. Or maybe I'm missing something? Thanks!
 
Re: Why don't online sites include cut in GIA listed diamond

alfsong|1403852632|3701918 said:
Hi All -
New to PS and so far - love it! Have been looking at diamonds online on PS vendor list and wondering why vendors like JA and WF don't tell you the quality of cut of their GIA diamonds. Important info and I don't understand why they don't list it, since GIA certainly includes it. Or maybe I'm missing something? Thanks!
Click to expand...

Actually GIA's cut grades are pretty sloppy and other cut standards are better.
GIA's top cut grade of Excellent allows some diamonds that are too deep.
We call them steep deeps.

Cutters and diamond sellers LOVE that steep deeps get an Excellent cut grade from GIA because it lets them cut heavier diamonds from a given piece of rough.
Better cut and light performance would require them to grind away more rough material and end up with a smaller diamond.
Few customers understand good cut, but every customer understands carat weight.

Here is a bullet-proof 2-step process to find a superbly-cut modern round brilliant diamond.
It only works for rounds.
It may pass up a few diamonds that experts with years of experience may have not rejected, but who cares?
You and I are not experts with years of experience.
We just want a simple way to identify well-cut diamonds.

Step 1 is the HCA. https://www.pricescope.com/tools/hca

Enter these 4 numbers from the GIA report"
Depth %
Table %
Crown Angle in degrees
Pavilion Angle in degrees

If the diamond scores over 2.0 reject it.
If it scores under 2.0 go on to step 2.
HCA is not an acceptance tool, just a rejection tool.

Step 2 is getting an Idealscope image. https://www.pricescope.com/tools/ideal-scope

Compare it to this reference chart. http://www.ideal-scope.com/1.using_reference_chart.asp



The reason step 2 is needed is the Crown and Pavilion angles entered into the HCA are actually each averages of the 8 angles around the eight sides of the diamond.
It's is possible some of the angles are different from others (a bad thing), but happen to average out to what would be a nice average.
(Kind of like how someone with one hand in boiling water and the other frozen in a block of ice could be said to feel pretty good on average. ) :bigsmile:
An Idealscope pic would reveal such wonky angles.

Another option is to only consider diamonds graded by AGS.
Unlike GIA's you can believe AGS's top cut grade.

idealscope_ref_44.png
 
Re: Why don't online sites include cut in GIA listed diamond

Nicely done Sir Kenneth! :appl:

Welcome Alfsong, glad you like us and found us to be helpful! Kenny has got you off to a great start, as you have more questions, please don't hesitate to ask. :wavey:

As to your original query -

Written by alfsong » 27 Jun 2014 02:03:
Hi All -
New to PS and so far - love it! Have been looking at diamonds online on PS vendor list and wondering why vendors like JA and WF don't tell you the quality of cut of their GIA diamonds. Important info and I don't understand why they don't list it, since GIA certainly includes it. Or maybe I'm missing something? Thanks!
Click to expand...

In the case of Whiteflash that sells mainly their own in house diamonds, they sell many AGS0 cut grade but some GIA for their Expert Selection range. As far as I am aware, WF use their own strict criteria to decide whether a particular diamond is worthy of representing their ACA ( AGS0 cut grade) or Expert Selection ( some GIA triple EX and AGS0). Although I believe GIA 3X is one of the criteria they use for their ES diamonds, not all GIA 3X are going to pass their inspections and be sold as such because the GIA Excellent cut grade can allow for less deserving proportion combos such as the steep/deeps which can show light leakage to receive the 3X grade, diamonds from this cut grade are not created equal and it's important to evaluate each with care.

From Whiteflash's website.

''Our Expert Selection category contains very high quality diamonds, many of which narrowly missed our A CUT ABOVE brand. Round diamonds in this category are ideal cut with hearts and arrows patterning. They must be certified as Ideal with AGS Triple 0 report or as Triple Ex by GIA. Expert Selection contains other shapes with superb cut quality including many AGS 0 Princess cuts. All diamonds in this category must have certification with the highest cut grades given by AGSL or GIA, and have outstanding light performance as evidenced in ASET and IDEAL scope images.



*While the GIA cut grading system is broader and more forgiving than AGS, GIA Triple Ex diamonds in the Expert Selection category are vetted for light performance on par with AGS Ideal. For more details please see our page on GIA Triple Excellent.''


James Allen use their own cut grade labels I believe as do many vendors, what criteria they use to base that on I don't know.
 
Re: Why don't online sites include cut in GIA listed diamond

Wow - highly informative! Thank you very much. And - I should have said I am looking for a Princess cut, so all the great info I could use for a round brilliant unfortunately won't work there.
 
Re: Why don't online sites include cut in GIA listed diamond

Alfsong,
GIA does not provide an overall cut quality grade on princess cuts, so that is why you are not seeing it in the GIA listings. It's quite unfortunate as you cannot tell much at all about the light performance qualities of these stones without further testing (images that many vendors provide help with this).
If you are looking for top performing princess, seek out AGS0 stones. They are analyzed by sophisticated ray tracing technology that take into account the influence of every facet.

Kenny-Lorelie,
Good info. Take heart that the subject line will attract many viewers to whom that info will be most relevant. :twirl:
 
Re: Why don't online sites include cut in GIA listed diamond

Great question Alf!
You're not alone.
Many consumers looking at online selections are confused by ratings that some sites assign to cut on Fancy Shaped diamonds. As discussed, GIA issues a cut grade for round diamonds.
Past the debate here on GIA's cut grade itself, I think many will agree that advertising a stone a "EX Cut Grade" when the stone has a GIA EX cut grade is transparent. Categorizing by cut grade with no GIA cut grade seems the opposite.
Personally I think this should be stressed more often- ratings tend to affect shopper's behavior, even if there's no basis in reality.
 
Re: Why don't online sites include cut in GIA listed diamond

Thanks for the Atta Girl, Rock Diamond, but I apologize for not being clear in my first post that I was looking for a Princess cut diamond. I mistakenly thought GIA grading applied to more than just the round brilliant. I very much appreciate the time spent to discuss grading of diamonds in general.

So to make sure I understand what’s being said, when a site like BN or B2C says a GIA Princess diamond is an “Excellent” or “Very Good” cut, it’s their own grading system they’re using?

Ok, I’m trying out my new learning, and I went to the PS Diamond Search and put in my criteria and I could click on the "AGS" box to pull up stones from that lab, (that certainly narrowed the field!) but couldn’t click on the AGS0 box. So now what am I not understanding?

I looked on the B2C website, they didn’t have any AGS graded stones at all, at least not that I could find.

And – just to give you the ballpark, I’m looking for a diamond probably between $1500-$2000.00, for an engagement ring.

So thanks in advance for the next round of responses, which will no doubt raise more questions. :rolleyes: :?:
 
Re: Why don't online sites include cut in GIA listed diamond

I think I properly gave the "attagirl"- it is an interesting topic alfsong :appl:

I'll make general comments- as opposed to commenting on any particular site
GIA does not grade the cut of any other shape besides round brilliant diamonds.
AGSL does indeed offer grading services including a cut grade for some fancy shapes.
Such stones are practically non existent- aside from Princess cuts, and certain cushions
You may find AGSL EX cut grade Princess Cuts on the market. Scarce, but they do exist.
On that count, I'd advise to looking at both AGSL EX cut grade princess cuts as well as well cut princess cuts graded by GIA.
In general the AGSL stones have a very different look than a "generic" princess cut- so look at both if possible to see which you prefer.

My advice to a consumer is to ask any question you may have of a seller about how they classify their diamonds- about cut or anything else.
 
Re: Why don't online sites include cut in GIA listed diamond

Rockdiamond|1403914548|3702466 said:
AGSL does indeed offer grading services including a cut grade for some fancy shapes.
Such stones are practically non existent- aside from Princess cuts, and certain cushions
You may find AGSL EX cut grade Princess Cuts on the market. Scarce, but they do exist.
On that count, I'd advise to looking at both AGSL EX cut grade princess cuts as well as well cut princess cuts graded by GIA.
In general the AGSL stones have a very different look than a "generic" princess cut- so look at both if possible to see which you prefer.

My advice to a consumer is to ask any question you may have of a seller about how they classify their diamonds- about cut or anything else.
Click to expand...
Just to clarify, I think RD is saying AGS 0 fancy cuts other than princess and certain cushions are practically non-existent. That is certainly true. But there is a decent selection AGS 0 princess available if you search.

It's also true that AGS Ideal cut princess cuts do have a very different look than "generic" princess cuts. Generic princess cuts are designed primarily for weight retention. In the process, much of the potential beauty is lost. An AGS 0 princess has levels of brightness and fire that generic princess don't have.

It's kind of like store-bought tomatoes as opposed to vine ripened homegrown tomatoes. The factory tomatoes are cultivated to be good for shipping, shelf life and low price. Homegrown are cultivated for taste.

Furthermore, its difficult to shop for "well cut" GIA Ex princess online because 1) there aren't many and 2) a GIA report does not give you enough information to know whether the stone has even decent light performance. You will need more information such as light performance images to buy remotely. Or you will have to look at a bunch of stones in person and find one that is really beautiful. But unless you view a true ideal cut in the mix, you will only see different "generic" candidates because that is what the market is full of.
 
Re: Why don't online sites include cut in GIA listed diamond

Thanks again for the great information! So now, how would I go about finding a local jeweler who would have AGS and other, I guess, more generic stones, so I could see the difference? I'm pretty convinced an AGS0 stone would be lovely and probably the way to go, but it would be nice to be able to see them in person. I live in the Seattle, WA area - would I just call up jewelers locally and see if they happen to have AGS graded Princess cut stones available to look at?
 
Re: Why don't online sites include cut in GIA listed diamond

I believe that there is an AGS website that will list dealers – that may assist you in finding a store that carries the princess cut stones in stock.
I would strongly encourage you to remove any prejudice you might have against one or the other before you look. Although I see their advantages, and also find the AGS stones beautiful, I do not agree with a lot of what Brian wrote about AGS versus "regular" princess cuts. I do agree that ags stones are very different, and furthermore, the AGS stones will have a more consistent look from one to the next. However I do not agree that you will automatically gravitate towards the AGS stone. In general AGS stones are going to look much smaller than regular Princess. I wouldn't say it's 100% given, but if the stores carrying the AGS L princess cuts, they may feel like Bryan, and suggest those more heavily than others.
And while there are some AGS stones available on the market, the number is miniscule compared to non-AGS stones – this and other factors brings up the price, and makes gs Princess stones much more difficult to find.
Having said all that, you need to find one to see now that you know that they exist. If you like them better they are beautiful as well.
 
Re: Why don't online sites include cut in GIA listed diamond

alfsong|1403938160|3702654 said:
Thanks again for the great information! So now, how would I go about finding a local jeweler who would have AGS and other, I guess, more generic stones, so I could see the difference? I'm pretty convinced an AGS0 stone would be lovely and probably the way to go, but it would be nice to be able to see them in person. I live in the Seattle, WA area - would I just call up jewelers locally and see if they happen to have AGS graded Princess cut stones available to look at?
Click to expand...
Yes, I would call around and find a reputable store that has a good selection of princess cuts in stock. As RD suggested, you can also go to the AGS website and locate a member store, although that alone might not guarantee that they have ideal princess in stock, or one in the size/quality you are looking for. But any reputable, knowledgeable jeweler in good standing can call a stone or two in for you to compare.

I disagree with RD that Ideal princess cuts look smaller than most generics. In fact I recently did a survey taking a small snippet of a popular size/quality of GIA princess from the global trading network. About 50 percent had depth percentages over 80%.
Of the stones that were not overly deep, many had tables larger than their depths which is a recipe for light leakage and other problems.
 
Re: Why don't online sites include cut in GIA listed diamond

I would agree to avoid princess cuts with depth ratios greater than 80%. I would not agree however that a stone whose table is larger than his depth necessarily indicates problems in performance.

In my experience physically selecting many princess cuts, a stone with a large table can be a problem, but it can be very beautiful as well – and, if it has a proper depth ratio, it also tends to look a lot larger than the stone with a smaller table such as the AGS type stones.
All this variation does make it more difficult for shoppers – and is a good selling point for AGS graded stones. However I still strongly urge you to look at different types to see what you love. AGS grading stones do have a consistent look, but you just may not like it.
 
Re: Why don't online sites include cut in GIA listed diamond

Well, that's a good reminder - to keep an open mind. I can tend to get a little fixated sometimes... And having not actually seen what we're talking about, clearly I need to do that. I found a couple of jewelry stores in my area where I can do some eyes-on evaluation - can't wait!

Thank you lovdajules, for the stone idea you posted - I like it! I did some looking online late last night and found a couple of others that seem pretty nice as well. Comments welcome!

http://www.briangavindiamonds.com/diamonds/diamond-details/0.620-g-vvs1-princess-diamond-ags-38590924

http://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-3062357.htm
 
Re: Why don't online sites include cut in GIA listed diamond

Alf- here's my impressions of general differences between stones that I would consider to be well cut non-AGS princess cuts, and AGS princess cuts.
As Bryan mentioned, there are many poorly cut overly deep princess cuts on the market.
Although it is not possible to select diamonds based on their measurements, it is sometimes possible to eliminate them.
When I am looking at GIA graded princess cuts, I like to find a depth in the low 70s, or high 60s. I've even seen some dazzling stones in the mid to low 60s.
When the other factors are correct, stones in this depth range will tend to have very good size for their weight.
In terms of appearance, stones like this will generally not have symmetrical patterns of sparkles . That is say, there will be a lot of smaller sparkles as opposed to larger flashes of light returning to your eyes from the stone.
In the best of cases, such stones can be quite bright and have a consistent sparkle from edge to edge. When I'm looking for such stones, that is what I like to see personally.
To qualify for an AGS zero Cut grade, Princess cut is going to have much higher crown, and much smaller table.
The generic examples I mentioned above will have much shallower crowns and larger tables.
The fact is, when put through tests for brilliance as they exist for diamonds, the AGS style stones return brighter flashes of light than the generic style stones that I'm speaking of.
The data that light performance testing provides is conclusive in one regard, but not in all regards. For example, does a buyer prefer a stone with patterning.
Brigher is not always better for all buyers when the alternative can be a stone that looks a bit larger and possesses a different type of sparkle.
Plus, you will likely find a premium for AGS graded stones.
If it turns out that that's the look you prefer, I wholeheartedly agree agree that they're worth the premium.
But if you do find that you prefer generic stones, don't feel bad. We'll cut generic stones are not "worse". Just different.
I look forward to hearing about your experiences.
 
Re: Why don't online sites include cut in GIA listed diamond

Well, I went looking and did find an extremely helpful gemologist who showed me an AGS Ideal cut and a couple of other of the more traditional cut Princess stones. I can definitely see the difference! And I think I like it! I did see the difference in visual size appearance, with the AGS stone appearing somewhat smaller, which is a little sad, but I do like how it looks.
 
Re: Why don't online sites include cut in GIA listed diamond

alfsong|1404106609|3703604 said:
Well, I went looking and did find an extremely helpful gemologist who showed me an AGS Ideal cut and a couple of other of the more traditional cut Princess stones. I can definitely see the difference! And I think I like it! I did see the difference in visual size appearance, with the AGS stone appearing somewhat smaller, which is a little sad, but I do like how it looks.
Click to expand...

Alf, it's important to bear in mind that if you are viewing diamonds in a purpose lit jewellery store, to see if you can view your selections in more everyday lighting conditions, that way you will know if the more ' commercial' cut Princess lose much steam compared to the AGS0, it's hard to generalize as one cannot account for individual preference and taste, but it's important to view any contenders in lighting where the stone will be worn as that will give you a much better idea of what appeals to you.
 
Re: Why don't online sites include cut in GIA listed diamond

Cool Alf!! Sounds like you got some context.
I agree with Lorelei about making sure to check different lighting.
I like the fact that you saw generic stones that looked larger than AGS stones of the same weight- because overall size is one big factor in how people perceive stones.. As Bryan pointed out, there are many overly deep stones on the market- it sounds like you saw some non AGS stones with good spread.
In terms of prices- was there a big difference?
 
Re: Why don't online sites include cut in GIA listed diamond

alfsong|1404106609|3703604 said:
Well, I went looking and did find an extremely helpful gemologist who showed me an AGS Ideal cut and a couple of other of the more traditional cut Princess stones. I can definitely see the difference! And I think I like it! I did see the difference in visual size appearance, with the AGS stone appearing somewhat smaller, which is a little sad, but I do like how it looks.
Click to expand...
Glad you were able to do some side by side comparisons. Nice to know you like the taste of homegrown tomatoes. :twirl:

While there are many overly deep stones on the market, there are also plenty of spready ones. The trick is finding one that has proper spread without compromising light performance. As Lorelie suggested, getting to see both in a variety of real world lighting conditions would really tell you alot.
 
Re: Why don't online sites include cut in GIA listed diamond

Thank you all for your help! I'm taking a little break to digest all this info and do a little more research. I am very grateful for this group and the willingness you have to inform and encourage!
Thanks -
Alfsong
 
Re: Why don't online sites include cut in GIA listed diamond

alfsong|1404604532|3707489 said:
Thank you all for your help! I'm taking a little break to digest all this info and do a little more research. I am very grateful for this group and the willingness you have to inform and encourage!
Thanks -
Alfsong
Click to expand...


Thanks for your kind words Alf, we appreciate it very much. Taking a break to digest the info is a good thing, I do that too with projects I am working on with potential analysis paralysis. Thanks also to David and Bryan for sharing their expertise!
 
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