Education on the use of the HCA tool for super ideal cut diamonds

[rak1]

Good day everyone, I am new to this and would like to ask for some assistance if anyone could shed some light on this for me. I am aware that the HCA tool is useful in screening poorly cut diamonds. As my knowledge is limited, forgive me if I am asking a silly question.
In the case of comparing super ideal cut diamonds only, does the lower HCA score still reflect a better performing diamond. Ie, 2 diamonds, both super ideal cut and one has a score of 0.9 (which performs better) and the other 1.5. I have searched and when trying to explain the limitations of the HCA score there is a a tendency to show a super ideal cut with a higher score outperforming a triple excellent (but non super ideal cut). I could not really find comparisons or videos explaining the use of the HCA score when applied to only super ideal cut diamonds.

I tend to buy diamonds online and outside of my country of residence due to a lack of similar options locally (that I am aware of).

I am looking at the website Brilliance.com. The seem to have many super ideal cut diamonds. Perhaps again ignorance on my part, but are you generally able to see clearly defined hearts and arrows in a super ideal cut? Some of the images I see, do not seem to be the case. Or are there many grades of a super ideal cut? I know a ASET scope image would be a useful tool, but if there is an absence of that option, is there an alternative.

Thank you very much in advance for anyone who can shed a light on this for me.

 

[Karl_K]

hca .9 is not necessarily better than an hca 1.6 they both pass.
Some less than honest sellers have tried to hijack the term super-ideal and incorrectly apply it.
Because its not a industry standardized term they can get by with it legally.
A super ideal stone as defined here is cut to known good proportions, has a gia ex or AGSL ags0 grading report, hearts and arrow images and a reflector image(aset/Ideal scope) showing light handling and a regular picture. Polish and lab symtry grades should be Ideal or EX depending on AGSL or GIA report.
Video is a plus.
Sometimes the reflector image is used as the arrows image and this is acceptable.
Any one of those thing are missing or is not in the top range its not super-ideal.

 

[Diamond_Enthusiast]

Some less than honest sellers have tried to hijack the term super-ideal and incorrectly apply it.

Agree with the above. Unfortunately there are quite a few of these examples of abuse of the term 'super-deal' around. Please be careful with these marketing definitions of super-ideal and stick to the definition suggested by @Karl_K above.

Here is an example this happening from a recent thread. There is even a super-ideal category with the search function! Not all diamonds returned from this search will be what PS members regard as super-ideal: https://www.pricescope.com/communit...-super-ideal-cut-i-if-diamond-for-37k.269411/

Unfortunately, on Brilliant Earth they have a "Super Ideal" category that obviously doesn't fit our standard of Super Ideal.


Edit @DejaWiz , @Tourmaline I think we were all posting at the same time!

For reference, here is the page explaining the PS recommended proportions for modern round brilliant diamonds:

Diamond Proportions

The physics of light-behavior within a diamond are reliably consistent, which means proportions measurements can be useful.

www.pricescope.com

 

[Ibrakeforpossums]

Brilliance assigns their own cut grades to all their diamonds, even the fancy cuts. It's essentially an opinion. This forum will be your best tool.
I bought a couple small low-color diamonds from them, they have a very large selection and good prices. But use caution.

 

[Wink]

The creator of the HCA tool, @Garry H (Cut Nut), says 2.0 or below is a pass, above gets worse and worse as the number goes higher.

Some will will want to say that below 1.0 is not acceptable as a ring stone, I emphatically disagree as I have sold so many of them that are absolutely incredible in any lighting. (Except for direct sunlight which Garry loves to point out...)

Personally, I say that when you find a great looking diamond that makes your heart flutter and your eyes happy, you have all you need. When I was an active seller, I used the tools to cut through the chaff and help me to provide the diamonds meeting the heart fluttering and happy eyes.

Wink

 

[oldminer]

Wink and Karl;
It would be a wonderful process to join you two and the firm(s) on Pricescope that legitimately use the Super-Ideal terminology only for those diamonds which meet the many scientific standards for the use of that description.

Without giving away the secret recipe for cutting such diamonds, would it be possible to create check-off list for consumers who could then inquire of any vendor if the "Super Ideal" diamond they were interested in met all these required elements. Unless the vendor wants to then become a fraud or a liar, they would be have to simply say they do or they don't. They might even want to say what parts they do require and which ones they don't bother with.

This definition provided for all users to read, cut and paste would be great for consumers to have access to. The devil is in the minute details of the Super Ideal cuts.

 

[Texas Leaguer]

As @Karl_K points out the term super-ideal has no universally defined standard. So if a diamond is being offered as a super ideal, a consumer needs to understand what that particular merchant's standard is.

Essentially, the term implies that the diamond passes some qualification or qualifications over and above a lab grade of Ideal. The AGS Lab is the leader in cut quality analysis with their light performance grading system. Yet, they do not grade optical precision (often referred to as optical symmetry or 3D symmetry). And it is possible for a diamond to get an Ideal grade without having perfect 3D facet precision. The degree of perfection in a hearts and arrows image is visual evidence of optical precision. So, a diamond with an AGS Triple Zero Ideal grade which also exhibits an outstanding hearts and arrows pattern can be accurately said to be a super ideal. Some vendors have additional specifications and qualifications for their brand of super ideal, though not all publish those details.

With regard to the HCA tool, since an AGS Triple Ideal has been through a sophisticated ray tracing system which directly measures the contribution of all 57 facets of a 3D model of the diamond, whereas the HCA tool relies on a few basic proportion parameters that are themselves rounded and averaged, an AGS Ideal report renders an HCA score moot.

 

[Wink]

Oh, wouldn't that be loverly, loverly.... (Music from My Fair Lady

)

There are already several great guidelines, such as the measurements allowed in their ACA line by WhiteFlash.

What will never be able to be posted as a guide is the absolutely necessary attention to detail needed in the Optical Symmetry. This must be viewed with the tools of the trade, such as the ASET tool and the Hearts and Arrows viewer. Two diamonds with identical crown angles, pavilion angels, table, star and lower girdle measurements can actually look quite different when Optical Symmetry is not properly done.

Wink

Edited to add: Drat, @Texas Leaguer at WhiteFlash posted while I was writing. Well said Bryan!

 

[Texas Leaguer]

Wink and Karl;

Without giving away the secret recipe for cutting such diamonds, would it be possible to create check-off list for consumers who could then inquire of any vendor if the "Super Ideal" diamond they were interested in met all these required elements.

@oldminer ,
I have always been skeptical of the concept that there is a "secret recipe" for precision cutting, though that claim or implication can be seen in the marketing materials of various enterprises. To me such an approach continues the long tradition of opacity in the jewelery industry, which is frustrating to the modern consumer raised in the information age.

Precision cutting requires more skill, more time, the best equipment, and a devotion to a philosophy of cutting for beauty over weight. (If any of that can be called a secret, it is the last point). It is certainly not easy to do. That is why we have for a decade published the full set of specifications and qualifications for our brand of super ideal. If other merchants can effectively implement that formula, they deserve a share of the business, Consumers benefit, and really the whole industry benefits.

Diamonds are very popular even though a large percentage are not cut for maximum beauty. Imagine how much more popular they could be if they were.

 

[oldminer]

So, a H&A viewer, Ideal-Scope or ASET scope along with an AGS000 report can give a consumer the best useful range of assurance.

The likelihood of getting a true Super Ideal by chance from nearly any other source than those few firms which specialize in such meticulous cutting is just about nil. If you find a diamond rated " Super Ideal" by some miscellaneous gem lab or vendor, it is very unlikely that such a diamond meets the true and complete set of Super Ideal parameters.

 

[Karl_K]

@oldminer
Over the years even with broad agreement over my baseline description above when it comes to details it has always blown up on the forum and I get emails saying in effect how dare you say that my diamonds are in the same class as another vendors.
Others took exception to the requirement that documentation/images have to be provided or what documentation/images were needed.

 

[oldminer]

Karl;
Such are the expected reactions to pressure being applied within the trade. Consumers don't have the influence as individuals to suggest or insist on standards, but experts in the field do have some degree of strength in numbers. Sellers generally resent or resist showing their cards due to the desire for various competitive advantages and their set of trade secrets. It is all pretty logical.

Progress comes slowly to those who show patience and persistence, especially when they are correct in their position. We have come a very long way in the 37 years I have been pushing for grading cut quality toward an open and accepted standard that seeks to define the very best small percentage of cut diamonds as distinct from the others spread out all around the uppermost tier of cut.

You came late to the party and have become a truly diligent expert relatively rapidly. Now welcome to the patience part of the effort. You'll occasionally get some abuse for doing the right thing. I consider positive, but polite and patient, disruption a vital tool in getting to the goal. Diamonds re being cut far better today than when I started to push it back in 1985.

 

[Garry H (Cut Nut)]

Some one has been reading Andrey the CEO's mind. He proposed a methodology for classification of these issues to John P and me a day or 3 before this posted thread
So things are happening
As Bryan and others mention there is a requirement for precision with Super Ideal-s.
However I would like to point out that at any single day there are about 10 times more 1.00 to 1.01ct diamonds cut and polished compared to 0.899 to 0.998ct diamonds. That statistically is wrong. There should be 15 times more of the lighter diamonds.
Diamond cutters employ as much or more skill compared to polishing super ideal cuts by cheating the system by cutting as close as they can to boundaries of GIA's X cut grade, X or VG symmetry and polish so as to achieve magic carat weights.

 

[Serg]

Diamond cutters employ as much or more skill compared to polishing super ideal cuts by cheating the system by cutting as close as they can to boundaries of GIA's X cut grade, X or VG symmetry and polish so as to achieve magic carat weights.

I doubt that "Cheating" is correct terminology in such case. I do not like to see such Blaming of skill-able cutters.

 

[rak1]

A massive thank you to all of you who were kind enough to share your knowledge and experience. It has been truly quiet the eye opening experience. I ultimately pulled out of a purchase because the photo listed on the order page didn't look like the one in the final video which I had requested. I was told, it just so happen to be the case that for the particular one I ordered, that they used a stock image. When all listings show very different images, and no disclaimer stating which uses of stock images, I find it difficult to commit to a purchase. I will spend some time reviewing more information shared on this thread. This community itself is diamond.

 

[Garry H (Cut Nut)]

I doubt that "Cheating" is correct terminology in such case. I do not like to see such Blaming of skill-able cutters.

I guess it is the equivalent of tax minimization Sergey?
It is up to Governments (or labs) to set laws (grades) and police them.
What is the boundary of minimization / evasion (maximisation/cheating in the case of diamonds)?
In the case of GIA setting a depth percentage boundary of 63% that is arrived at by the addition of crown height, girdle thickness and pavilion depth %. Was the creation of extra facets on the girdle to reduce girdle thickness that meant that diamonds that measured more than 64% maximization or cheating?

 

[Serg]

I guess it is the equivalent of tax minimization Sergey?
It is up to Governments (or labs) to set laws (grades) and police them.
What is the boundary of minimization / evasion (maximisation/cheating in the case of diamonds)?
In the case of GIA setting a depth percentage boundary of 63% that is arrived at by the addition of crown height, girdle thickness and pavilion depth %. Was the creation of extra facets on the girdle to reduce girdle thickness that meant that diamonds that measured more than 64% maximization or cheating?

1)"by cheating the system by cutting as close as they can to boundaries " it is not same "Was the creation of extra facets on the girdle to reduce girdle thickness ."

GIA fixed the problem with extra facets 2-3 years ago, did not they? . Cutters did not cheated GIA, they showed well known weaknesses of GIA cut grading approach( GIA could used real total hight or Spread to avoid such weaknesses in the GIA grading system.)
Do you any other such samples of "cheating" from cutters?

2) Some( not all) offshore operations cheat a tax system. But if somebody use his deep knowledge of tax laws to receive tax return( for investments, education, health support) it can not been considered as cheating

Sometimes you play by words to promote HCA by creating fears instead to delivery objective information. Where is your boundary between cheating ( creating fears) and real consumer eduction?

P/s I see much more samples when a government cheats companies , citizens by tax rules than when companies cheat a tax system

 

[Garry H (Cut Nut)]

1)"by cheating the system by cutting as close as they can to boundaries " it is not same "Was the creation of extra facets on the girdle to reduce girdle thickness ."

GIA fixed the problem with extra facets 2-3 years ago, did not they? . Cutters did not cheated GIA, they showed well known weaknesses of GIA cut grading approach( GIA could used real total hight or Spread to avoid such weaknesses in the GIA grading system.)
Do you any other such samples of "cheating" from cutters?

2) Some( not all) offshore operations cheat a tax system. But if somebody use his deep knowledge of tax laws to receive tax return( for investments, education, health support) it can not been considered as cheating

Sometimes you play by words to promote HCA by creating fears instead to delivery objective information. Where is your boundary between cheating ( creating fears) and real consumer eduction?

P/s I see much more samples when a government cheats companies , citizens by tax rules than when companies cheat a tax system

Very spurious reply Sergey?
1. if that is not cheating what was it?

64.9% depth that recieved GIA's XXX cut grade????
2. what you describe in tax is called minimization. It is not illegal. You first #1 means that many consumers were cheated.

You do not agree with all HCA parameters but you also do not agree with GIA steeper and deeper proportion combinations. My boundary is lower than yours for reasons I firmly believe in - they probably should be shallower still as I consider dirty diamond related problems.
I should not share my fears about GIA's cut grades?
Are AGS cheating by creating fear because more than half GIA's X cut diamonds would rate AGS 1, AGS2 or worse?

 

[Garry H (Cut Nut)]

1)"by cheating the system by cutting as close as they can to boundaries " it is not same "Was the creation of extra facets on the girdle to reduce girdle thickness ."
GIA fixed the problem with extra facets 2-3 years ago, did not they? . Cutters did not cheated GIA, they showed well known weaknesses of GIA cut grading approach( GIA could used real total hight or Spread to avoid such weaknesses in the GIA grading system.)

I believed you some years ago when you said GIA fixed this Sergey.
Now a lot of these 3,883 stones will be typo's - but clearly there is still a problem and a lot of people are being cheated.

 

[Diamond_Enthusiast]

As a consumer, I just want to make a few comments and share my own experience with shopping for diamonds online and how I've used recommended proportions and HCA tool.

When searching on a vendor's website, the first thing I do as part of the 'search' is input the recommended proportions as parameters in my search. I find this really helpful in filtering results to focus on diamonds with the best potential. I understand that there are probably diamonds outside of the parameters that are beautiful too but it is simply too difficult to review them all. Search results are sometimes in the hundreds and thousands for vendors primarily accessing virtual inventory (eg: BN and JA).

Here I just want to comment on the matter of including 'Super Ideal' the way it is positioned beside actual lab cut grades in search parameters on a scale is very misleading (per the example in my earlier post). Not all consumers will be across the spectrum of cut grades officially used by labs and understand that 'Super Ideal' in this instance is simply the vendor's opinion. Some consumers will be buying a diamond for the first time ever for a proposal and are overwhelmed by the task of choosing a good stone begin with. The provision of this 'Super Ideal' in a search is a bit of trap in IMO, a short cut to finding the best of the best as if it was a cut grade assigned by an independent lab. One the other hand, if it instead had on the top end of the scale the name of the vendor's signature line of diamonds, I'd be fine with that because it is obviously vendor defined.

When using diamond search tool on PS, I use the recommended proportions and add to filter diamonds with 'Excellent' HCA score. Again this is a really helpful way to narrow the search results to identify stones with the best potential.

I'm thankful for having these recommended proportions and the HCA tool to help me with buying diamonds online. These tools have been tremendously helpful in the filtering process for stones without advanced images, so I can just check lab reports and focus on reviewing videos/photos of the stones with the best potential.

Buying diamonds from vetted super ideal vendors and diamond listings with advanced images. Best case scenario! This is the easiest because I'm provided with pretty much everything I need to make an informed decision. With the vetted super ideal vendors' signature diamonds (eg: WF ACA), all the proportions are already in recommended proportions and there are advanced images to confirm their light performance. Easy peasy!

Now just a comment about those steep-deep stones - don't like them. Leaky or not, it is simply because I want my diamonds to have the face up size for its carat weight.

 

[Serg]

Very spurious reply Sergey?
1. if that is not cheating what was it?

64.9% depth that recieved GIA's XXX cut grade????
2. what you describe in tax is called minimization. It is not illegal. You first #1 means that many consumers were cheated.

You do not agree with all HCA parameters but you also do not agree with GIA steeper and deeper proportion combinations. My boundary is lower than yours for reasons I firmly believe in - they probably should be shallower still as I consider dirty diamond related problems.
I should not share my fears about GIA's cut grades?
Are AGS cheating by creating fear because more than half GIA's X cut diamonds would rate AGS 1, AGS2 or worse?

Diamonds with 3% and 5% girdle thickness have almost the same Optical performance if other parameters are the same.

The different thing will only be the spread (apparent size) parameter. it is reasonable that diamonds with negative spread are discounted because of their lower apparent size.
You refer to 65% total depth diamonds with very thick girdle as proofs that HCA protects consumers from diamonds with bad optical performance better than GIA cut grading system. It is a pity that with your approach you scare consumers instead of giving them real knowledge and confidence for choosing diamonds. In my private test the diamonds with P 41.3 Cr 35 and even with very thick girdle have better LIFE (optical performance) than shallow diamonds P40.3 Cr35 that become dark at short observation distance.


re: they probably should be shallower still as I consider dirty diamond related problems.

HCA favors too much dull shallow diamonds just because shallow angles are better for Dirty! diamonds.
For clean diamonds I see much better correlation with GIA grades than with HCA. Both systems have advantages and critical problems, but GIA system is more correct for clean diamonds when HCA is more correct for dirty diamonds.
Instead of scaring consumers with steep deep diamonds just explain them that HCA is the best grading system for dirty diamonds.

Cutters do not cheat GIA grading system because they do not provide any kind of wrong information to GIA. GIA itself scans diamonds and calculates grades, so it is up to GIA to address weaknesses of the system.
Similarly, those who find legal opportunities with legal tex return are not cheating because they follow the law and, in fact, know the law better than even the lawmakers. On the contrary, cheating is when you need yourself to spend a lot of time to learn complicated tax legislation in order to be not cheated or if you have to pay lawyers fortunes in order to receive all due by the law tax returns.

 

[lanz88]

You do not agree with all HCA parameters but you also do not agree with GIA steeper and deeper proportion combinations. My boundary is lower than yours for reasons I firmly believe in - they probably should be shallower still as I consider dirty diamond related problems.
I should not share my fears about GIA's cut grades?
Are AGS cheating by creating fear because more than half GIA's X cut diamonds would rate AGS 1, AGS2 or worse?

Hi Garry can you please explain what you mean by dirty diamond related problems?

 

[Garry H (Cut Nut)]

Diamonds with 3% and 5% girdle thickness have almost the same Optical performance if other parameters are the same.

The different thing will only be the spread (apparent size) parameter. it is reasonable that diamonds with negative spread are discounted because of their lower apparent size.
You refer to 65% total depth diamonds with very thick girdle as proofs that HCA protects consumers from diamonds with bad optical performance better than GIA cut grading system. It is a pity that with your approach you scare consumers instead of giving them real knowledge and confidence for choosing diamonds. In my private test the diamonds with P 41.3 Cr 35 and even with very thick girdle have better LIFE (optical performance) than shallow diamonds P40.3 Cr35 that become dark at short observation distance.


re: they probably should be shallower still as I consider dirty diamond related problems.

HCA favors too much dull shallow diamonds just because shallow angles are better for Dirty! diamonds.
For clean diamonds I see much better correlation with GIA grades than with HCA. Both systems have advantages and critical problems, but GIA system is more correct for clean diamonds when HCA is more correct for dirty diamonds.
Instead of scaring consumers with steep deep diamonds just explain them that HCA is the best grading system for dirty diamonds.

Cutters do not cheat GIA grading system because they do not provide any kind of wrong information to GIA. GIA itself scans diamonds and calculates grades, so it is up to GIA to address weaknesses of the system.
Similarly, those who find legal opportunities with legal tex return are not cheating because they follow the law and, in fact, know the law better than even the lawmakers. On the contrary, cheating is when you need yourself to spend a lot of time to learn complicated tax legislation in order to be not cheated or if you have to pay lawyers fortunes in order to receive all due by the law tax returns.

Sergey do you know what Diamond Enthusiast mentioned? I put these proportions together as recommended proportions early this year.
You have a problem with them clearly.

Perhaps we should run a poll as to how often people clean their diamonds? I imagine PriceScope forum participants clean their diamonds some where between twice and a hundred times more often than most people.

Diamond Proportions

The physics of light-behavior within a diamond are reliably consistent, which means proportions measurements can be useful.

www.pricescope.com

Regarding cheating, I am sorry Sergey, but your argument is not worth consideration. Check the discounts on RapNet on +63% depth stones. I concealed the discount column.
At least half have less than -30% discount.
And so much for GIA fixing the problem??? Do you have an answer to that?

 

[Garry H (Cut Nut)]

Hi Garry can you please explain what you mean by dirty diamond related problems?

This is from a GIA article - tried to find it but failed:

A light ray striking the inner surface of a diamond is reflected back into the diamond because it strikes outside of the critical angle. Right: Notice how the same light ray, striking from the same angle, is now able to escape (transmit) through the pavilion facet because the oil on the surface has changed the critical angle.

The problem is when you look at the outer facets on a round slightly deep diamond your line of sight goes into the diamond, bounces of the same side pavilion facet and then leaves and is swalloed up by the oily greasy gunk on the opposite side pavilion. A slightly shallow diamond suffers less of this effect:

Photos i took recently of a clients dirty diamond ring - you can see it is mostly the outer facets that suffer.

 

[Garry H (Cut Nut)]

Hi Garry can you please explain what you mean by dirty diamond related problems?

This is a model made with Sergey's software but I changed the refractive index to that of Fluorite (which is about the same as oil and grease).
Infact as diamond bends the entry light much more, the effect is far worse than this in dirty diamond, because the second pavilion interception is a far steeper angle.


So even large areas of the main crown facets will mainly show the dirt and gunk on the pavilion.

 

[lanz88]

This is from a GIA article - tried to find it but failed:

A light ray striking the inner surface of a diamond is reflected back into the diamond because it strikes outside of the critical angle. Right: Notice how the same light ray, striking from the same angle, is now able to escape (transmit) through the pavilion facet because the oil on the surface has changed the critical angle.

The problem is when you look at the outer facets on a round slightly deep diamond your line of sight goes into the diamond, bounces of the same side pavilion facet and then leaves and is swalloed up by the oily greasy gunk on the opposite side pavilion. A slightly shallow diamond suffers less of this effect:

Photos i took recently of a clients dirty diamond ring - you can see it is mostly the outer facets that suffer.

Thank you for that information. I just wanted to clarify what you mean by slightly deep? Are you talking about the total depth of the diamond? If so what would you consider slightly deep? What would be the best depth that you would say wouldn’t get as affected by oil and grease etc?

 

[Garry H (Cut Nut)]

Thank you for that information. I just wanted to clarify what you mean by slightly deep? Are you talking about the total depth of the diamond? If so what would you consider slightly deep? What would be the best depth that you would say wouldn’t get as affected by oil and grease etc?

On the PriceScope recommended proportions if you drop one degree of crown angle or 0.2 degrees of pavilion angle (but not both together) you will see a marked difference in 2 diamonds worn without cleaning in the same environment (like earrings switched from ear to ear every day) after a week or more.
I have done this experiment.

 

[lanz88]

On the PriceScope recommended proportions if you drop one degree of crown angle or 0.2 degrees of pavilion angle (but not both together) you will see a marked difference in 2 diamonds worn without cleaning in the same environment (like earrings switched from ear to ear every day) after a week or more.
I have done this experiment.

Ohh ok so you’re referring to the C/P angles? Nothing to do with the total depth of the diamond?!

 

[Garry H (Cut Nut)]

Ohh ok so you’re referring to the C/P angles? Nothing to do with the total depth of the diamond?!

Refraction and reflection don't talk %'s. They talk angles As Sergey correctly mentioned - a thicker girdle has very little impact on light performance - but greatly increases depth % and shrinks spread.

 

[lanz88]

Refraction and reflection don't talk %'s. They talk angles As Sergey correctly mentioned - a thicker girdle has very little impact on light performance - but greatly increases depth % and shrinks spread.

Sorry still trying to get my head around it!

I have two diamonds.
Diamond 1 is 35/40.8 57% 61.5%
Diamond 2 is 34.5/40.8 56% 62.6%

Diamond 1 is significantly better in performance, it seldom looks dirty and is always edge to edge sparkly.

Diamond 2 has poor performance not long after it’s cleaned, especially on the edges.

Both diamonds have great ideal scope images with no leakage.

@Garry H (Cut Nut) why would diamond 1 be a significantly better performer? It goes against what you have mentioned above?