Find your diamond
Find your jewelry
shape
carat
color
clarity

cut nuts

test0321

Rough_Rock
Joined
Mar 21, 2021
Messages
12
Hi everybody. I would like to discuss about the (super) ideal cut. As I learned on the internet, there were many websites listed the data of super ideal cut. Some of them were very detail (for example, with the Crown height %) and some were not.

Recently I leaned about the diamond proportion and found a website created by HRD lab could calculate if the proportion of a diamond is excellent. Here it is:


I used two diamond to do the test.

Diamond A get a 1.2 HCA score and the data are fit for the ideal cut.

diamond A 4C3F91AD-07DA-48B8-99C6-3D9892C83A88.jpeg

Diamond B get over 5 HCA score and the data are not fit for the idea cut.
diamond B
D5D83AE9-7C5A-42EE-813F-E2034969AFC8.jpeg

But interesting thing is that the proportion of diamond A is only very good (I found out that it is because the Pavilion depth % is not deep enough) but the proportion of diamond B is excellent even though it doesn’t fall into the ideal cut.

Just base on the data, would it be possible that diamond B is more excellent although it has a bad HCA score and not very good data. It has a excellent proportion?
 

lovedogs

Super_Ideal_Rock
Premium
Joined
Jul 31, 2014
Messages
12,880
Hi everybody. I would like to discuss about the (super) ideal cut. As I learned on the internet, there were many websites listed the data of super ideal cut. Some of them were very detail (for example, with the Crown height %) and some were not.

Recently I leaned about the diamond proportion and found a website created by HRD lab could calculate if the proportion of a diamond is excellent. Here it is:


I used two diamond to do the test.

Diamond A get a 1.2 HCA score and the data are fit for the ideal cut.

diamond A 4C3F91AD-07DA-48B8-99C6-3D9892C83A88.jpeg

Diamond B get over 5 HCA score and the data are not fit for the idea cut.
diamond B
D5D83AE9-7C5A-42EE-813F-E2034969AFC8.jpeg

But interesting thing is that the proportion of diamond A is only very good (I found out that it is because the Pavilion depth % is not deep enough) but the proportion of diamond B is excellent even though it doesn’t fall into the ideal cut.

Just base on the data, would it be possible that diamond B is more excellent although it has a bad HCA score and not very good data. It has a excellent proportion?

Diamond B is not good at all. 41.6 is too steep and 63.4 is too deep. I would ignore pretty much anything that says this diamond is anywhere new "super ideal".
 

AllAboardTheBlingTrain

Brilliant_Rock
Joined
Apr 22, 2020
Messages
1,275
If you check the PDF included in the link to the calculator, it shows what are the ranges to get excellent/very good etc on HRD’s scale. For me, no matter what the proportions I entered, it always shows the result as “very good”, leading me to conclude that the calculator is faulty. I would be loath to take any one such internet tool as the definitive guide. I know it’s published on the HRD site but we’ve no way of knowing what grade the diamond would actually get if graded by HRD.

If you want to “verify” a specific diamond’s HCA score you can use the cut estimator on diamondscreener to see what that diamond (modern round brilliant only) would score using the GIA and AGS charts. You want to get a diamond that comfortably scores GIA Ex and AGS 0 (not borderline for either).

Ultimately I’d pick a stone that passes several “hurdles” even if it misses out on one such hurdle. Between A and B, A looks like the better bet for me.
 

test0321

Rough_Rock
Joined
Mar 21, 2021
Messages
12
Diamond B is not good at all. 41.6 is too steep and 63.4 is too deep. I would ignore pretty much anything that says this diamond is anywhere new "super ideal".


If you check the PDF included in the link to the calculator, it shows what are the ranges to get excellent/very good etc on HRD’s scale. For me, no matter what the proportions I entered, it always shows the result as “very good”, leading me to conclude that the calculator is faulty. I would be loath to take any one such internet tool as the definitive guide. I know it’s published on the HRD site but we’ve no way of knowing what grade the diamond would actually get if graded by HRD.

If you want to “verify” a specific diamond’s HCA score you can use the cut estimator on diamondscreener to see what that diamond (modern round brilliant only) would score using the GIA and AGS charts. You want to get a diamond that comfortably scores GIA Ex and AGS 0 (not borderline for either).

Ultimately I’d pick a stone that passes several “hurdles” even if it misses out on one such hurdle. Between A and B, A looks like the better bet for me.

Thank you very much.
I can see all the H&A on the diamond. But I found many people said 35.5/40.6 will have an issue of light lackcage. If I don’t have the ASET/ideal scope. How can I confirm it? Thank you very much.
 

sledge

Ideal_Rock
Premium
Joined
Apr 23, 2018
Messages
4,515
Assuming both stones are MRB’s, diamond B is what we call a “steep & deep”. The pavilion angle is too steep and not complimentary to the crown angle. Consequently, the stone has an overall depth of 63.4. Not only will this stone have poor performance due to light leakage but it will appear smaller in diameter than an truly ideal cut stone of similar weight because the extra carat weight is stuffed in the depth of the stone. This stone was cut to maximize weight and consequently profit, and not maximum beauty. Regardless of the HRD data, this is not an ideal cut stone.

Diamond A may or may not be okay. The crown and pavilion angles are much more complimentary and may work well. However, the screen shots indicate both stones are GIA graded so you have to account for GIA’s method of rounding & averaging their values, which in short says it’s a maybe. I would recommend you request ASET and H&A images, both of which are rarely available from most standard retailers, but it’s still worth an ask. If none can be provided you can solidify the return policy, buy your own scopes and make further determination once it arrives and you can confirm light performance and symmetry precision with your hand held scopes.
 

sledge

Ideal_Rock
Premium
Joined
Apr 23, 2018
Messages
4,515
I can see all the H&A on the diamond.

For clarity of those reading along, hearts is observed by looking at the bottom of the stone and arrows the top of the stone. Therefore, with loose stones you can see both. With a mounted stone, the setting will prevent you from seeing hearts.

Also, it takes a little work to see H&A if you don't have the proper scopes.


Lastly, even a poorly cut stone may exhibit some formation of "hearts & arrows" but would not be of technical merit to be considered a true H&A stone. The devil is in the details. This article explains in more detail.

 

test0321

Rough_Rock
Joined
Mar 21, 2021
Messages
12
For clarity of those reading along, hearts is observed by looking at the bottom of the stone and arrows the top of the stone. Therefore, with loose stones you can see both. With a mounted stone, the setting will prevent you from seeing hearts.

Also, it takes a little work to see H&A if you don't have the proper scopes.


Lastly, even a poorly cut stone may exhibit some formation of "hearts & arrows" but would not be of technical merit to be considered a true H&A stone. The devil is in the details. This article explains in more detail.


Thank you. I saw the diamond in person. And I used the telescope to see it also.

I am not an expert. But based on the view on the telescope. Diamond A has a 90-95% H&A. The connections of thr arrow and the body are perfect. Just a little uneven on the end of the arrow (the position near the center).

The diamond is owned by a local vendor and no return policy under the vendor. And no ASET, ideal scope.

Are there any methods that I can check if the diamond has light leakage, especially by naked eye?

Besides, I am curious why 99% of vendors in my city do not have the ASET tools, etc. I think it’s really important for customers.
 

sledge

Ideal_Rock
Premium
Joined
Apr 23, 2018
Messages
4,515
A few thoughts. Have you considered purchasing the scopes and shipped to your house? If so, your jeweler should let you analyze the stones in-store using the scopes. The caveat being the stone(s) don't get sold prior to scopes arriving. However, you'd think a small deposit would hold the stones or at least give you first rights if there is another interested buyer in the same stone(s).

By the way, if you only buy one scope, an ASET is recommended.

An alternative would be to utilize an experienced appraiser with all the advanced scopes & tools in his/her inventory so you can gain an independent opinion. Most jewelers should be open to this idea, although it will cost you a few bucks.

That said, here are some videos that may help you see the differences in real life. The first is more obvious, whereas the second is much closer and harder to discern the differences. The key take away is you are looking for the same similarities in both comparisons.


 

John Pollard

Rough_Rock
Staff member
Premium
Joined
Dec 2, 2020
Messages
6
Lastly, even a poorly cut stone may exhibit some formation of "hearts & arrows" but would not be of technical merit to be considered a true H&A stone. The devil is in the details. This article explains in more detail.


@sledge, that's important info and a great grading process resource. @test0321 you're getting good guidance.

I recently updated our PriceScope Hearts and Arrows Diamonds page. It now includes a chart showing a range of appearances diamonds can take in a H&A viewer. That might be interesting for added context.

https://www.pricescope.com/education/diamond-cut/hearts-and-arrows-diamonds#Examples
 

test0321

Rough_Rock
Joined
Mar 21, 2021
Messages
12
A few thoughts. Have you considered purchasing the scopes and shipped to your house? If so, your jeweler should let you analyze the stones in-store using the scopes. The caveat being the stone(s) don't get sold prior to scopes arriving. However, you'd think a small deposit would hold the stones or at least give you first rights if there is another interested buyer in the same stone(s).

By the way, if you only buy one scope, an ASET is recommended.

An alternative would be to utilize an experienced appraiser with all the advanced scopes & tools in his/her inventory so you can gain an independent opinion. Most jewelers should be open to this idea, although it will cost you a few bucks.

That said, here are some videos that may help you see the differences in real life. The first is more obvious, whereas the second is much closer and harder to discern the differences. The key take away is you are looking for the same similarities in both comparisons.




@sledge, that's important info and a great grading process resource. @test0321 you're getting good guidance.

I recently updated our PriceScope Hearts and Arrows Diamonds page. It now includes a chart showing a range of appearances diamonds can take in a H&A viewer. That might be interesting for added context.

https://www.pricescope.com/education/diamond-cut/hearts-and-arrows-diamonds#Examples


I have always found the HRD approach to cut grading was primarily designed to over complicate while being "different" and more "scientific" than GIA's.
But wholesomely useless

Thank you. I will buy the HCA/ ideal scope but maybe have some time cuz I can’t buy one in my city.

I saw the PriceScope Hearts and Arrows Diamonds page and found that 35.5/40.6 is under the sweet line. It’s sound nice?

I don’t have the tool now but I have a video provided by the vendor that I uploaded as below.

 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
16,147
Thank you. I will buy the HCA/ ideal scope but maybe have some time cuz I can’t buy one in my city.

I saw the PriceScope Hearts and Arrows Diamonds page and found that 35.5/40.6 is under the sweet line. It’s sound nice?

I don’t have the tool now but I have a video provided by the vendor that I uploaded as below.


The video is of no use other than to see the ring style.
I ship Idea-scopes all over the world.
 
Be a part of the community It's free, join today!
    Queen Elizabeth II and Prince Philip’s Love Story told through Jewelry
    Queen Elizabeth II and Prince Philip’s Love Story told through Jewelry
    Style File: Emma Watson
    Style File: Emma Watson
    F. Scott Fitzgerald and Zelda Sayre's Wedding
    F. Scott Fitzgerald and Zelda Sayre's Wedding

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top