Need help! GIA XXX with HCA of 3.7

[Rockdiamond]

Garry- you say it's not worth commenting on, yet this is the second time you've done so.
About the email you sent- we don't have to agree Garry- people do vary.
I do not feel its "easy to find bad cut GIA XXX stones"
There were no idealscope images- therefore no comparison to the image above

 

[Garry H (Cut Nut)]

Garry- you say it's not worth commenting on, yet this is the second time you've done so.
About the email you sent- we don't have to agree Garry- people do vary.
I do not feel its "easy to find bad cut GIA XXX stones"
There were no idealscope images- therefore no comparison to the image above

Since the vendor I sent 5 sample stones to RockDiamond only does ASET and not Ideal-Scope, there were no ideal-scopes. But David could clearly see the GIA reports and the photo's with dark zones under the table and H&A's images.
Here is one of the ASET images for a GIA XXX.
Please be good David

 

[Rockdiamond]

Hi Garry,
I'll be as good as I can be
We agree that the ASET does indicate minor leakage in the table.
There are other aspects on which we disagree.
1) Does minor leakage under table as indicated in ASET equate to "badly cut"?
My contention is that it does not necessarily. Which, by the way is in line with GIA's conclusion- which you certainly have the right to disagree with
2) does the diamond you posted the ASET of look like the good, or worse images in the IS chart?
While there might be a resemblance, I don't believe it's that close. Furthermore we have not seen an IS or ASET of the diamond the OP was asking about which is why I feel posting the chart is appropriate in this case.

3) Should ASET be used to make purchase decisions?
My feeling is that visual inspection is far more important.
GIA's cut grade was designed incorporating many human observations.
I have found GIA EX cut grade stones that I might not have picked- yet others might have.
For example, some people don't like H&A- and prefer a more "disorganized" type of sparkle- my comments about scintillation have to do with stones I've seen that have this look, obtain GIA EX cut grade, yet score poorly on HCA. I may not be expressing it to your satisfaction.
This should not be taken as a knock on HCA- it works remarkably well in it's designed purpose.
I like "Super Ideal" stones. But it's also important to point out there is a cost associated with cutting to this standard.
I have also found stones that we can describe as "lesser" cut- that may ( for example) show minor leakage under the table in ASET- that are more desirable to some observers based on their appearance. such stones may trade at substantially lower prices as well- which is an important aspect for lot of buyers

 

[Dancing Fire]

I like "Super Ideal" stones. But it's also important to point out there is a cost associated with cutting to this standard.
I have also found stones that we can describe as "lesser" cut- that may ( for example) show minor leakage under the table in ASET- that are more desirable to some observers based on their appearance. such stones may trade at substantially lower prices as well- which is an important aspect for lot of buyers

David
IYO..how deep is too deep? how shallow is too shallow? I mean, at what point do you say to yourself "I don't need to look at this stone" b/c I know it will be ugly..

 

[Rockdiamond]

Great question DF.
As you surely know, I was trained at Harry Winston, in the '70's ( 1970's ) looking at really well cut stones that were generally 60 table, 60 depth.
When "Ideal" cut started to gain prominence, I really felt they were too deep, at 62%. As time has gone by I have learned to appreciate both.
Above 62%, I'm thinking the stone may be too deep- although GIA will allow stones deeper than 62 into EX cut grade.
Having said that, I have seen Fancy Colored Round diamonds as deep as 65% ( generally brown diamonds) that have looked really good- albeit a bit small for the weight- which is acceptable in a brown round. But aside from the size issue, they did not necessarily have a look of a badly cut diamond.
On the shallow end of things, there's much less leeway before things start to go haywire.
59% maybe.
A lot of the more shallow stones start to have larger tables, which then allows the "ring of death"- where the girdle reflects into the table.
This is far worse in my eyes than a small amount of leakage under the table.

About when I won;t even look....well, if the stone is in front of me, most times I like to look just for the heck of it.

 

[Dancing Fire]

Great question DF.
As you surely know, I was trained at Harry Winston, in the '70's ( 1970's ) looking at really well cut stones that were generally 60 table, 60 depth.
When "Ideal" cut started to gain prominence, I really felt they were too deep, at 62%. As time has gone by I have learned to appreciate both.
Above 62%, I'm thinking the stone may be too deep- although GIA will allow stones deeper than 62 into EX cut grade.
Having said that, I have seen Fancy Colored Round diamonds as deep as 65% ( generally brown diamonds) that have looked really good- albeit a bit small for the weight- which is acceptable in a brown round. But aside from the size issue, they did not necessarily have a look of a badly cut diamond.
On the shallow end of things, there's much less leeway before things start to go haywire.
59% maybe.
A lot of the more shallow stones start to have larger tables, which then allows the "ring of death"- where the girdle reflects into the table.
This is far worse in my eyes than a small amount of leakage under the table.

About when I won;t even look....well, if the stone is in front of me, most times I like to look just for the heck of it.

The problem is that the online buyers don't have the stone in front them, so we must eliminate the poorly cut stones with the "lab report information and tools" we have available instead of shipping stones back and forth across the country.

 

[Garry H (Cut Nut)]

Great question DF.
As you surely know, I was trained at Harry Winston, in the '70's ( 1970's ) looking at really well cut stones that were generally 60 table, 60 depth.
When "Ideal" cut started to gain prominence, I really felt they were too deep, at 62%. As time has gone by I have learned to appreciate both.
Above 62%, I'm thinking the stone may be too deep- although GIA will allow stones deeper than 62 into EX cut grade.
Having said that, I have seen Fancy Colored Round diamonds as deep as 65% ( generally brown diamonds) that have looked really good- albeit a bit small for the weight- which is acceptable in a brown round. But aside from the size issue, they did not necessarily have a look of a badly cut diamond.
On the shallow end of things, there's much less leeway before things start to go haywire.
59% maybe.
A lot of the more shallow stones start to have larger tables, which then allows the "ring of death"- where the girdle reflects into the table.
This is far worse in my eyes than a small amount of leakage under the table.

About when I won;t even look....well, if the stone is in front of me, most times I like to look just for the heck of it.

The problem is that the online buyers don't have the stone in front them, so we must eliminate the poorly cut stones with the "lab report information and tools" we have available instead of shipping stones back and forth across the country.

Nonsense DF, you just give David RockDiamond a blank check and he does it all for you.
You can trust him, he is a jeweler.
An expert.

 

[Dancing Fire]

Great question DF.
As you surely know, I was trained at Harry Winston, in the '70's ( 1970's ) looking at really well cut stones that were generally 60 table, 60 depth.
When "Ideal" cut started to gain prominence, I really felt they were too deep, at 62%. As time has gone by I have learned to appreciate both.
Above 62%, I'm thinking the stone may be too deep- although GIA will allow stones deeper than 62 into EX cut grade.
Having said that, I have seen Fancy Colored Round diamonds as deep as 65% ( generally brown diamonds) that have looked really good- albeit a bit small for the weight- which is acceptable in a brown round. But aside from the size issue, they did not necessarily have a look of a badly cut diamond.
On the shallow end of things, there's much less leeway before things start to go haywire.
59% maybe.
A lot of the more shallow stones start to have larger tables, which then allows the "ring of death"- where the girdle reflects into the table.
This is far worse in my eyes than a small amount of leakage under the table.

About when I won;t even look....well, if the stone is in front of me, most times I like to look just for the heck of it.

The problem is that the online buyers don't have the stone in front them, so we must eliminate the poorly cut stones with the "lab report information and tools" we have available instead of shipping stones back and forth across the country.

Nonsense DF, you just give David RockDiamond a blank check and he does it all for you.
You can trust him, he is a jeweler.
An expert.

I was hoping for RD to give me a blank check .I'm sure he'll trust my eyes...

 

[Garry H (Cut Nut)]

Great question DF.
As you surely know, I was trained at Harry Winston, in the '70's ( 1970's ) looking at really well cut stones that were generally 60 table, 60 depth.
When "Ideal" cut started to gain prominence, I really felt they were too deep, at 62%. As time has gone by I have learned to appreciate both.
Above 62%, I'm thinking the stone may be too deep- although GIA will allow stones deeper than 62 into EX cut grade.

David some simple math shows that to maintain those same crown and pavilion angles (which can indeed be close to Tolkowsky's) for each 1% of table size (smaller) results in an extra 0.35 degrees of depth.
There for at 56% table size the depth should be +1.4%.

This means your maximum depth for a 56% table diamond would be 62+1.4 = 63.4%.
GIA would never ever allow that in its Ex cut grade.
So Harry Winston's rules, and yours are not practical (something I have witnessed when shown HW rules for optimum cushion shaped proportions by one of their suppliers - which were a waste of ink).

Most people on this board would not like to go much over 62% on a 56% table sized diamond. GIA dings at about 63% for those table sizes. And the stone that I showed the ASET, that you choose to think was slight leakage (hahahaha), with GIA XXX - you might like to see what its proportions are from the suppliers info.
Its a dog, and your prepared to go lower than dog status?

 

[Rockdiamond]

DF- I agree, online buyers don't have the luxury of seeing the stone- meaning they need to buy blind - or use some sort of system ( HCA) OR find a dealer they are comfortable with.
This has all sorts of implications.
For one thing, clarity- if a buyer can't trust the person assessing the stone for them- or they want to eliminate a dealers eyes, and buy using HCA, for example, they can't reasonably go below VS2- or even VS1 if it's a larger stone.
I have seen VS2 RBC's with visible imperfections.
Certainly a lot of people choose this method- but they will be giving up size, or spending more than they might of they felt comfortable buying an SI stone.
I get to speak to thousands of buyers a year- and unfortunately, many are under the impression an SI clarity is defective by it's very nature....which is not the case. There are a percentage of eye clean SI goods out there- even in larger sizes.
At this point, if I was buying a high dollar watch, I'd probably send you a blank check DF- we have been discussing this for...what... almost 10 years

Garry- All due respect, but please don't put words in my mouth.
I never mentioned any angles.
No need to be insulting.

 

[msop04]

minor/slight leakage in an Ideal Scope is not visible to the eyes.

OP may find this thread helpful, HCA 3.2 with excellent(no leakage) IS image: [URL='https://www.pricescope.com/community/threads/bad-hca-good-is-image.186794/']https://www.pricescope.com/community/threads/bad-hca-good-is-image.186794/[/URL]

Threadjack Alert...

JulieN, I'm really behind on this thread, but I'm very interested in what you have to say (or anyone else with experience, for that matter...) about HCA >2 but with great performance. I don't know if you've seen it, but there is a thread for this very discussion.

 

[msop04]

The chart posted above has no place in a discussion about HCA stores, or diamonds with a GIA EX cut grade. You're not going to see stones graded EX Cut grade by GIA that look anything like the stones on the right side of the chart.
It's simply inaccurate- and misleading to say a stone scoring 3.7 is worse than a stone scoring 1 when it comes to cut.
If someone has looked at different stones and knows what the HCA looks for, then it can be a useful tool.
BUT, some people will pick a stone that scores 3.7 over one that scores 1 based on aspects which HCA can not distinguish.
Things like LGF.
scarletbird, what this means is how wide the shafts are when you see the arrows pattern in the diamond.The higher the LGF%, the more narrow the shafts will be.
Narrower shafts will not produce a distinct H&A pattern.
Some people prefer a distinct H&A pattern, others a more disorganized type of sparkle.

Some people will prefer more contrast ( rewarded in HCA) while others prefer more scintillation( dinged by HCA)
GIA does not punish stones for things HCA does- yet we're talking about preference.
For this reason, GIA EX cut grade means more than HCA to noobies who are actually looking at diamonds- period.
scarletbird - if you can get to places that carry diamonds and have a look for yourself, it will be helpful.
Its a major league purchase and worth your time.

Rockdiamond, this is exactly the explanation I needed to read concerning HCA >2 for GIA X stones. Thank you for posting this -- it has really helped explain a lot and "fill in some holes" that I have been wondering about, and it really makes sense! Especially since different people prefer a variety of "looks" from their diamonds!

As it's been said many times over... "people vary."

RD, I hope you don't mind if I repost this on a different thread??

 

[Garry H (Cut Nut)]

minor/slight leakage in an Ideal Scope is not visible to the eyes.

OP may find this thread helpful, HCA 3.2 with excellent(no leakage) IS image: [URL='https://www.pricescope.com/community/threads/bad-hca-good-is-image.186794/']https://www.pricescope.com/community/threads/bad-hca-good-is-image.186794/[/URL]

Threadjack Alert...

JulieN, I'm really behind on this thread, but I'm very interested in what you have to say (or anyone else with experience, for that matter...) about HCA >2 but with great performance. I don't know if you've seen it, but there is a thread for this very discussion.

Do you have your stones proportions msop?

 

[msop04]

Hi Garry! I don't have them right now, but I can get them -- report is in our safe deposit box. (you'd think I'd have them memorized by now!! )

 

[Garry H (Cut Nut)]

Hi Garry! I don't have them right now, but I can get them -- report is in our safe deposit box. (you'd think I'd have them memorized by now!! )

Get the #'s for me and I will run them thru the new HCA2 data

 

[The sun is shining]

Gosh Garry. Be careful with what you are offering. You have no idea how many people could put their hand up for a "me too!"