GIA proportions match AGS0 - does that make it ideal?

[potatowned]

Knowing that a cut grade of AGS0 is considered ideal, if the GIA proportions all match a cut grade of 0 in all categories, from table %, crown angle, pavilion depth, culet and girdle, does that mean I've found an "ideal" cut diamond? What other factors could come into play that would prevent this from being an amazing stone, from a cut perspective?

I know that AGS0 stones can still be greater than 2 under HCA, particularly if it is an older GS0 grading. If it is below an HCA score of 2, and the proportions all meet AGS0 grades, should I be comfortable buying sight unseen?

 

[canvasback]

Correct me if I'm wrong someone.... but the difference in this case is that the AGS0 must go through a light performance rating. This rating and stamp of approval is something that the "numbers" alone cannot tell you.

 

[Johannes89]

im kinda wondering about that too .... but as far as im concerned id say the cut is ideal if the gia ex falls also into the ags 0 grades.
About the lightperformance its a different story.
Since light performance isnt only an effect of the angles but also other factors which arent measured by gia ...

so for me id say cutcrade yes, lightperformance no

 

[RockyRacoon]

Knowing that a cut grade of AGS0 is considered ideal, if the GIA proportions all match a cut grade of 0 in all categories, from table %, crown angle, pavilion depth, culet and girdle, does that mean I've found an "ideal" cut diamond?

That does not mean you've found a stone that AGS would consider Ideal.

GIA rounds their figures quite dramatically.

The non-rounded figures are necessary to get an idea of the actual stone, if you're going to make any judgement based on numbers.

GIA + Idealscope should do the trick!

 

[potatowned]

Knowing that a cut grade of AGS0 is considered ideal, if the GIA proportions all match a cut grade of 0 in all categories, from table %, crown angle, pavilion depth, culet and girdle, does that mean I've found an "ideal" cut diamond?

That does not mean you've found a stone that AGS would consider Ideal.

GIA rounds their figures quite dramatically.

The non-rounded figures are necessary to get an idea of the actual stone, if you're going to make any judgement based on numbers.

GIA + Idealscope should do the trick!

I've been using a combination of GIA Excellent, HCA<2, Proportions that meet AGS0, and idealscope.

Unfortunately, I don't know how to read idealscope!!!

What are your thoughts on something like this?

 

[potatowned]

Knowing that a cut grade of AGS0 is considered ideal, if the GIA proportions all match a cut grade of 0 in all categories, from table %, crown angle, pavilion depth, culet and girdle, does that mean I've found an "ideal" cut diamond?

That does not mean you've found a stone that AGS would consider Ideal.

GIA rounds their figures quite dramatically.

The non-rounded figures are necessary to get an idea of the actual stone, if you're going to make any judgement based on numbers.

GIA + Idealscope should do the trick!

I've been using a combination of GIA Excellent, HCA<2, Proportions that meet AGS0, and idealscope.

Unfortunately, I don't know how to read idealscope!!!

What are your thoughts on something like this?

 

[Diamond_Hawk]

Potatowned,

No 2D “proportions” can assure AGS 0 light performance. There are cut-charts used as guidelines, but the AGSL ray-traces the entire diamond (not just averaged numbers of facet-groups). So a diamond can have nice-looking 2D proportions, and even conform to 2D charts, but the actual 3D performance score may or may not be Ideal.

The IS has strong light return. At a glance the table seems on the high side, which isn’t a problem if you like that look. Can you link to the grading report?

 

[potatowned]

Potatowned,

No 2D “proportions” can assure AGS 0 light performance. There are cut-charts used as guidelines, but the AGSL ray-traces the entire diamond (not just averaged numbers of facet-groups). So a diamond can have nice-looking 2D proportions, and even conform to 2D charts, but the actual 3D performance score may or may not be Ideal.

The IS has strong light return. At a glance the table seems on the high side, which isn’t a problem if you like that look. Can you link to the grading report?

Unfortunately, it is only a GIA report: http://images.b2cjewels.com/Images//Certificate//6047729.pdf

It does score a 1.8 on the HCA tool though.

The rest of the images I have uploaded to this thread, which I am having trouble getting responses on:

http://pricescope.com/forum/viewtopic.php?t=206820#p3764507

THANK YOU!

 

[Karl_K]

once a vendor is identified the trade members can not comment.
Sorry.
There are several prosumers that can help however.

 

[potatowned]

I didn't know that. Is that a forum rule? I wouldn't mind if someone wanted to PM me and give me their input, or sell me a stone. I really wouldnt.

 

[Karl_K]

I didn't know that. Is that a forum rule? I wouldn't mind if someone wanted to PM me and give me their input, or sell me a stone. I really wouldnt.

Yes it is a forum rule.
There are no PM on this board.

 

[WinkHPD]

Actually, we can comment to answer a question asked or to correct a misstatement of fact.

I do agree that it would be better had we been given the numbers without knowing who the vendor is, but I am pleased to see Diamond_Hawk call the larger table size without knowing the numbers, says good things about his skills!

Without commenting on this particular diamond I want to address our OP's original question. Does finding a GIA that has all the "right numbers" mean that it is also a "right performer" by AGS standards?

That has been correctly stated as a no.

Part of the problem is the preciseness of the cutting which is measured by neither AGS or GIA, but is done much more poorly by GIA with its huge rounding issues. The preciseness of the cutting will have eye visible effects even between two diamonds of the same exact measurements. One or both may have that pleasing H&A pattern under the scopes, but one may still be more sparkly and show more dispersion than the other if it is more precisely cut. The initial virtual facets of the more precisely cut diamond will likely be larger and thus show larger flashes of both white and colored light. This just simply can not be seen on a piece of paper and is yet one more reason to only buy from a vendor with a solid return policy.

And it is another good also to try to see more than one diamond at a time so that you can see which your eyes like better.

Wink

 

[Karl_K]

Actually, we can comment to answer a question asked or to correct a misstatement of fact.

That is true I should have been more clear.
But if you read the other thread the OP wants to know which one to buy which is what I was talking about not being able to help with specific stones rather than questions of general facts.
With the exception of correcting wrong information.

 

[WinkHPD]

Ah, well, I have to admit I am not a big fan of thread hopping to answer questions, gets entirely too confusing for words if all the requested info is not where I am.

Seems like you and I are on the same page then.

Wink

 

[potatowned]

Thanks, that is sound advice. I plan on only buying from a place with a bulletproof return policy.

My problem is that I have a lot of trouble discerning between diamonds of varying quality. They all look so similar to me, hence my reliance on #s, ASET, IS images, etc.

May I ask a general question about table size? This is not specific to any particular diamond, but I would like to know your thoughts on a larger table size, with a shallower crown angle and shorter pavilion height. I understand that with a larger table, there is a trade-off between brilliance and fire, but would any of you hesitate to deem a diamond "ideal cut" if the table is larger? Say, 59-61%, assuming the other proportions are correct?

For example, a diamond with a table of 61%, depth at 59%, shallow crown angle of 32. pavilion depth of 43% (angle of 41) gives you a nice 1.8 on HCA, but this is obviously outside what is traditionally considered ideal.

Would such a diamond return less fire? (I read the thread on the 60/60 vs tolkowsky..., but I wanted some additional opinions.)

 

[cflutist]

I hate to say this, but how about just cut to the chase and buy a "SuperIdeal"/H&A diamond from one of the dealers such as Crafted By Infinity from HPD, or "Signature" from BGD, or "ACA" from WF. They do all the homework for you. That is one of the reasons that I ordered a Custom "Cut to Order" 2.3+ ct. F-SI1 or better CBI diamond from Wink at HPD. Good luck with your search.

 

[potatowned]

Thanks. By nature, I like doing my research, so I am generally less inclined to just give someone my money without knowing what it is they are providing me. I also like getting good value for my dollar, which is why I am asking all these questions.

If budget was not an issue, I would certainly go to GOG, or HPD, or Brian Gavin and simply buy an ideal cut 1.5c diamond that I know my girlfriend will love. Unfortunately, I am very budget conscious so here I am doing my own search.

 

[Dancing Fire]

Thanks. By nature, I like doing my research, so I am generally less inclined to just give someone my money without knowing what it is they are providing me. I also like getting good value for my dollar, which is why I am asking all these questions.

If budget was not an issue, I would certainly go to GOG, or HPD, or Brian Gavin and simply buy an ideal cut 1.5c diamond that I know my girlfriend will love. Unfortunately, I am very budget conscious so here I am doing my own search.

I can tell ya one thing about buying diamonds...your not gonna find a filet mignon for hamburger price...

 

[Texas Leaguer]

Would such a diamond return less fire? (I read the thread on the 60/60 vs tolkowsky..., but I wanted some additional opinions.)

Yes, you would be trading off some fire for a little additional white light return. Tolkowsky himself recognized and commented about this tradeoff. It's a matter of personal taste, but fire is one of the most alluring characteristics of diamond performance for many people.

 

[potatowned]

Thanks. By nature, I like doing my research, so I am generally less inclined to just give someone my money without knowing what it is they are providing me. I also like getting good value for my dollar, which is why I am asking all these questions.

If budget was not an issue, I would certainly go to GOG, or HPD, or Brian Gavin and simply buy an ideal cut 1.5c diamond that I know my girlfriend will love. Unfortunately, I am very budget conscious so here I am doing my own search.

I can tell ya one thing about buying diamonds...your not gonna find a filet mignon for hamburger price...

LOL I understand that and my expectations are realistic. Can you fault me for wanting to understand what I am buying though? Like I said, even if money was no object, I would still like to know as much about what I'm buying. I think I would be an unresponsible consumer if I just walked into my local jeweler and bought whatever he gave me.

 

[potatowned]

Would such a diamond return less fire? (I read the thread on the 60/60 vs tolkowsky..., but I wanted some additional opinions.)

Yes, you would be trading off some fire for a little additional white light return. Tolkowsky himself recognized and commented about this tradeoff. It's a matter of personal taste, but fire is one of the most alluring characteristics of diamond performance for many people.

It would be so easy if I could just ask my girlfriend which she preferred? Size/brilliance vs smaller size, more fire!

 

[WinkHPD]

Would such a diamond return less fire? (I read the thread on the 60/60 vs tolkowsky..., but I wanted some additional opinions.)

Yes, you would be trading off some fire for a little additional white light return. Tolkowsky himself recognized and commented about this tradeoff. It's a matter of personal taste, but fire is one of the most alluring characteristics of diamond performance for many people.

It would be so easy if I could just ask my girlfriend which she preferred? Size/brilliance vs smaller size, more fire!

Always good to know these things. A lot of men have their Lady involved in the decision, and of course, a lot would rather do it as a surprise.

Which ever you do will be the right way for you, but having her involved goes a LONG way to insuring that you are getting her what SHE wants too.

Wink

 

[Texas Leaguer]

Thanks. By nature, I like doing my research, so I am generally less inclined to just give someone my money without knowing what it is they are providing me. I also like getting good value for my dollar, which is why I am asking all these questions.

If budget was not an issue, I would certainly go to GOG, or HPD, or Brian Gavin and simply buy an ideal cut 1.5c diamond that I know my girlfriend will love. Unfortunately, I am very budget conscious so here I am doing my own search.

I can tell ya one thing about buying diamonds...your not gonna find a filet mignon for hamburger price...

LOL I understand that and my expectations are realistic. Can you fault me for wanting to understand what I am buying though? Like I said, even if money was no object, I would still like to know as much about what I'm buying. I think I would be an unresponsible consumer if I just walked into my local jeweler and bought whatever he gave me.

Can't fault you at all. Learning the finer points about diamond quality is what this forum is all about. You will appreciate your diamond that much more if you take the time to understand its various quality characteristics. It will enable you to select a diamond that will hit the sweet spot on your personal matrix of preferences.

You will see a bias toward cut quality here. Without top quality cutting you will not be getting all the performance out of the diamond that is possible. Within that strata of top cut quality there is still room for personal preference. Many people feel that the optimal cut is one that maximizes the various aspects of light performance in a balanced way without giving up too much of any one.