Can a GIA ex/ex/ex diamond score 5.0 on HCA tool?

[InnaR]

I recently read the topics here on Pricescope about the GIA ex/ex/ex diamond that was sold by one of the high end vendors.
The numbers did not look so good to me, so I plugged them into HCA and got the following results:
Light Return - Good
Fire - Fair
Scintillation - Fair
Spread
or diameter for weight - Very Good
Total Visual Performance 5.0 - Good - Only if price is your main criterion

My first stone was from Tiffany. It was GIA ex/ex/ex as well and it scored I think about 3.8 on HCA. I returned it and am still cannot get over the fact that high end stores sell very average cut stones for about 30% more than truly excellent cut stone from on line vendors.

So my questions are:
1. Can a GIA ex/ex/ex/ stone score 5.0 on HCA?
2. Are there good triple ex and bed triple ex GIA stones?
3. Would two GIA ex/ex/ex G VS1 1.0 carat stones cost the same if one score 1.7 and the other one scored 5.0 on HCA?
4. And the last one - why high end stores even care steep/deep stones if they are already charging extra 30% for the name and certainly can pick the cream of the crop for their customers?

 

[Dreamer_D]

1. Can a GIA ex/ex/ex/ stone score 5.0 on HCA?

Probably.

2. Are there good triple ex and bed triple ex GIA stones?

I suppose it depends what you mean by "bad". There are GIA Ex stones that would not be graded AGS0 for cut by AGS. If someone is seeking the most technically precise RB with AGS0 level optics, there are some GIA stones that will not fit that bill.

3. Would two GIA ex/ex/ex G VS1 1.0 carat stones cost the same if one score 1.7 and the other one scored 5.0 on HCA?

Nope. The industry as a whole does not care about such things. The caveat being that a GIA Ex that can be braded as an H&A stone would likely cost more than a GIA Ex than cannot, and the former will cost more than the latter.

4. And the last one - why high end stores even care steep/deep stones if they are already charging extra 30% for the name and certainly can pick the cream of the crop for their customers?

There are not TRUE steep-deep stones in the GIA Ex category in my opinion, that is a little hyperbole that passes around these parts. Beyond that, the type of stores you mention only care about GIA cut grade, if they care at all. Some don't offer stones with GIA reports and have their own in house grading. I have no clue what criteria they use! Cartier RBs in particular look suspect to me in photos, though I have not seen them in person. Many of those high end stores put a premium on the rarity factors of color and clarity rather than cut.

 

[Rockdiamond]

1. Can a GIA ex/ex/ex/ stone score 5.0 on HCA?

Probably.

2. Are there good triple ex and bed triple ex GIA stones?

I suppose it depends what you mean by "bad". There are GIA Ex stones that would not be graded AGS0 for cut by AGS. If someone is seeking the most technically precise RB with AGS0 level optics, there are some GIA stones that will not fit that bill.

3. Would two GIA ex/ex/ex G VS1 1.0 carat stones cost the same if one score 1.7 and the other one scored 5.0 on HCA?

Nope. The industry as a whole does not care about such things. The caveat being that a GIA Ex that can be braded as an H&A stone would likely cost more than a GIA Ex than cannot, and the former will cost more than the latter.

4. And the last one - why high end stores even care steep/deep stones if they are already charging extra 30% for the name and certainly can pick the cream of the crop for their customers?

There are not TRUE steep-deep stones in the GIA Ex category in my opinion, that is a little hyperbole that passes around these parts. Beyond that, the type of stores you mention only care about GIA cut grade, if they care at all. Some don't offer stones with GIA reports and have their own in house grading. I have no clue what criteria they use! Cartier RBs in particular look suspect to me in photos, though I have not seen them in person. Many of those high end stores put a premium on the rarity factors of color and clarity rather than cut.

+1000

Great post.
It's a mistake to use what we focus on here, and necessarily transfer it to other places without examination. That is to say- some GIA EX cut grade stones that score poorly on HCA may have visual characteristics that some well meaning sellers with integrity look for.

But without a doubt, let's not give the benefit of the doubt easily.
There's a lot of badly cut stones without GIA reports being passed of wrongly as "well cut"

 

[yssie]

1. Can a GIA ex/ex/ex/ stone score 5.0 on HCA?

Probably.

2. Are there good triple ex and bed triple ex GIA stones?

I suppose it depends what you mean by "bad". There are GIA Ex stones that would not be graded AGS0 for cut by AGS. If someone is seeking the most technically precise RB with AGS0 level optics, there are some GIA stones that will not fit that bill.

3. Would two GIA ex/ex/ex G VS1 1.0 carat stones cost the same if one score 1.7 and the other one scored 5.0 on HCA?

Nope. The industry as a whole does not care about such things. The caveat being that a GIA Ex that can be braded as an H&A stone would likely cost more than a GIA Ex than cannot, and the former will cost more than the latter.

4. And the last one - why high end stores even care steep/deep stones if they are already charging extra 30% for the name and certainly can pick the cream of the crop for their customers?

There are not TRUE steep-deep stones in the GIA Ex category in my opinion, that is a little hyperbole that passes around these parts. Beyond that, the type of stores you mention only care about GIA cut grade, if they care at all. Some don't offer stones with GIA reports and have their own in house grading. I have no clue what criteria they use! Cartier RBs in particular look suspect to me in photos, though I have not seen them in person. Many of those high end stores put a premium on the rarity factors of color and clarity rather than cut.

+1000

Great post.
It's a mistake to use what we focus on here, and necessarily transfer it to other places without examination. That is to say- some GIA EX cut grade stones that score poorly on HCA may have visual characteristics that some well meaning sellers with integrity look for.

But without a doubt, let's not give the benefit of the doubt easily.
There's a lot of badly cut stones without GIA reports being passed of wrongly as "well cut"

+3

 

[kindred]

I recently read the topics here on Pricescope about the GIA ex/ex/ex diamond that was sold by one of the high end vendors...

I missed those threads. Do you happen to have links?

 

[MadisonGirl]

Gahh.... by any chance are you referring to my diamond???

[URL='https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/']https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/[/URL]

I've been recently spending more time on the this forum and discovered the HCA tool... and those were the results I got when I plugged in my numbers.

The stone looks rather dark in the pics I have but figured that was just poor picture/lighting. When I went to go see the diamond it was bright and sparkly.

Is the tool very accurate, i.e. is it possible to have a lower HCA score and still look good?

Siiiiigh... ring was very expensive... would be very disappointing if the diamond wasn't very brilliant.

 

[Dreamer_D]

Gahh.... by any chance are you referring to my diamond???

[URL='https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/']https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/[/URL]

I've been recently spending more time on the this forum and discovered the HCA tool... and those were the results I got when I plugged in my numbers.

The stone looks rather dark in the pics I have but figured that was just poor picture/lighting. When I went to go see the diamond it was bright and sparkly.

Is the tool very accurate, i.e. is it possible to have a lower HCA score and still look good?

Siiiiigh... ring was very expensive... would be very disappointing if the diamond wasn't very brilliant.

Read the replies my friend No one said anything about GIA Ex stones being poor. This is a technical issue about cut, not a commentary on your ring or a disparagement of GIA Ex cut quality IMO ( I don't know if Inna is even referencing your ring, this topic has come up many times on PS).

 

[InnaR]

I recently read the topics here on Pricescope about the GIA ex/ex/ex diamond that was sold by one of the high end vendors...

I missed those threads. Do you happen to have links?

Kindred,
I don't think I should post the link, since the user did not ask for opinions on the diamond. So my post is more of a my attempt to learn few new things. I did search RockyTalky and found few discussion of GIA excellent cut diamonds that scored low on HCA. I am a strong believer that with old cut stones customers need to use their own eyes when selecting a diamond, however with modern cuts (probably because they are more predictable) I would want to know that all all of the numbers align
I am also interested to learn how stores like Tiffany or Cartier select their diamonds.

 

[InnaR]

Madison,
I am sorry, but I am referring to your ring. I apologize if it came out the wrong way, and I tried to avoid any direct reference to it. I personally think that it looks stunning on the pictures, and based on some of the reading I did and David's and Dreamer's replies it has all chances to be as stunning as any other GIA ex/ex/ex diamond.

Since it's not easy to evaluate the character of a modern round cut from pictures, I always look at the numbers to see if it's BIC or a FIC and so on. When I plugged your numbers it came out with 5.0. I couldn't stop thinking about it and decided to ask on the learning forum (instead of commenting in your topic) and to make the topic as general as possible.

I found many topics where customers were advised to stay away from stones that score higher than 2.0 on HCA and in many cases great alternatives were found through this forum.

I am one of those customers (only I did the reading and decided to return a Tiffany ring without starting a special topic on it). I ended up with amazing Whiteflash diamond for about half price I paid at Tiffany's. I upgraded it three times since then and all three of them were as amazing as Whiteflash itself.

It was not easy for me to start this topic, but since you found it, please consider it only a topic for my own educational purposes and not discussion of your diamond credentials.

 

[InnaR]

Many of those high end stores put a premium on the rarity factors of color and clarity rather than cut.

Dreamer,
I agree. However their rarity markup applies to all color/clarity combinations, not just the rare ones.

 

[distracts]

4. And the last one - why high end stores even care steep/deep stones if they are already charging extra 30% for the name and certainly can pick the cream of the crop for their customers?

Because most consumers don't care, and ideal cut stones are priced higher than non-ideals, which would mean the store's profit margin would be less. It's 100% a profit thing.

 

[MadisonGirl]

Inna, your post didn't come out the wrong way. I actually did come across the HCA tool prior to reading your post and when I saw the score I meant to start a thread on it, you just beat me to it.

I'm not really sure I understand HCA but I did talk to my cousin after the HCA score freaked me out. He assures me that the ring/diamond looks beautiful (still don't have the ring... not helping the situation). I trust him... he is rather picky and his job is to inspect some of the world's finest gems and he would never steer me wrong. So I'll probably stick with my stone and I'll just keep this bit of info in my back pocket.

I think the info is helpful (might've been more helpful before I bought my ring ) but if I think my stone looks great then I guess it really shouldn't matter what the tool or any other lab report tells me.

 

[yssie]

Gahh.... by any chance are you referring to my diamond???

[URL='https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/']https://www.pricescope.com/community/threads/harry-winston-micropave-on-round-brilliant-diamond.176125/[/URL]

I've been recently spending more time on the this forum and discovered the HCA tool... and those were the results I got when I plugged in my numbers.

The stone looks rather dark in the pics I have but figured that was just poor picture/lighting. When I went to go see the diamond it was bright and sparkly.

Is the tool very accurate, i.e. is it possible to have a lower HCA score and still look good?

Siiiiigh... ring was very expensive... would be very disappointing if the diamond wasn't very brilliant.

There isn't a tool in the world that's going to be 100% accurate 100% of the time (unless its one that you created to highlight your personal preferences I guess!), especially when you consider how much of all of this is subjective.

Prime example - this is my dream stone, it's not even a GIA EX
GIA VG (cut grade demoted b/c of proportions), HCA 2.3
http://www.jamesallen.com/diamonds/H-VS1-Very%20Good-Cut-Round-Diamond-1346299.asp


GIA EX, HCA 1.2
http://www.jamesallen.com/diamonds/H-VVS2-Excellent-Cut-Round-Diamond-1390119.asp


GIA EX, HCA 5.7
http://www.jamesallen.com/diamonds/J-VS2-Excellent-Cut-Round-Diamond-1491866.asp


GIA EX, HCA 4.6
http://www.jamesallen.com/diamonds/J-VVS1-Excellent-Cut-Round-Diamond-1384122.asp


Neither numbers on GIA report nor HCA tell you about minor facet proportions/arrangements (unless brillianteering is extreme enough that GIA demotes cut grade)
GIA EX, HCA 1.8
http://www.jamesallen.com/diamonds/G-SI1-Excellent-Cut-Round-Diamond-1397149.asp


This from another thread - GIA/HCA does not tell you about optical symmetry
GIA EX, HCA 2.8
http://www.jamesallen.com/diamonds/E-VVS2-Excellent-Cut-Round-Diamond-1424821.asp

 

[InnaR]

Madison,
If you want to get more opinions from pricescope community you might want to start a new topic, this time in RockyTalky. I am sure you will get many different opinion, suggestions and overall great help.

Yssie,
Wow. I would never guess that some of those stones score that low. The forth stone has what I thought a good combination of crown/pavilion angles for a BIC. I am sure that on Ideal Scope the grey leakage areas would be more obvious, but on a JA virtual loop this stone looks absolutely normal.

 

[Dreamer_D]

I am a fan of the HCA for consumers who are looking for a diamond with very precise proportions. I am a consumer like that, and use the HCA to help select my own modern RBs.

But I also believe that some of the nuances of cut we quibble about on PS are subtle, and not necessary for every consumer. In many cases, GIA Ex is sufficient to predict a beautiful diamond, certainly more beautiful than the majority on the market.

 

[yssie]

Madison,
If you want to get more opinions from pricescope community you might want to start a new topic, this time in RockyTalky. I am sure you will get many different opinion, suggestions and overall great help.

Yssie,
Wow. I would never guess that some of those stones score that low. The forth stone has what I thought a good combination of crown/pavilion angles for a BIC. I am sure that on Ideal Scope the grey leakage areas would be more obvious, but on a JA virtual loop this stone looks absolutely normal.

It looks like a super stone, I wouldn't hesitate to recommend it for further inspection - low HCA is not indicative of a problem here.

Basically, as Dreamer says, it depends on how much you want to quibble. If you just want a pretty stone that's easy, GIA EX or AGS0/AGS1 + HCA, if you do want to nitpick you need to know the merits and limitations of all the tools you're nitpicking with..

 

[MadisonGirl]

Thanks Dreamer and Yssie... I appreciate you input and feedback.

And sorry Inna... it seems I have hijacked your thread a bit.