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oldminer

Ideal_Rock
Trade
Joined
Sep 3, 2000
Messages
6,697
It is with absolute certainty that the vast majority of diamonds that have been sold to consumers in the past 50 years have been primarily in the 2B to 4A category of the AGA Cut Classes. Many, even most, of them look very nice or even excellent and most owners are very happy with these diamonds. Even today, most diamonds sold in the USA are 2B to 4A in spite of all the extra and readily available knowledge that consumers can now easily access. What does that say? I think it says most people need to control their spending budget sufficiently that they will agree to take a compromise on cut quality as well as to compromise of color, clarity and weight. It is purely logical and ought not concern us.

For sure, the AGA Cut Class promotes cut quality as a parameter of what creates a high quality diamond, but it does not FORCE anyone who wishes to buy anything they want to do differently. RockDiamond and others have a huge audience to sell to, larger than the small body of consumers who especially look at parameters and charts, who will take an expert's word and what they see with their own eyes as sufficient data to decide to make a purchase. We can be happy for these consumers as they are buying what they want in the manner that they choose. For this smaller body of cut conscious shoppers that Pricescope especially fosters, I think the AGA Cut Class tool is just one more tool in the screening arsenal for this select group of consumers who are looking to maximize a particular characteristic of diamonds, light performance.

The vast majority of consumers don't put such great emphasis on light performance and are willing to look at the huge variety of alternatively cut stones. No problem. That is why there is a free market and information is freely given in all directions. No harm is being done by buying such a personal item any way you want to. Sellers who offer alternatives often sound like dissenters, but really they are the voice of reason on occasion, too. Keeping an open mind about learning what YOU, the consumer, prefers is a healthy thing. This tool is not the way everyone should buy a diamond, but it will be highly useful for a good number of consumers. It will also inform those who choose to buy alternative cuts some things which may be important in the nature of exactly how an expert (me) believes they have compromised in their choice of a diamond. It may not deter them from buying, but they will better understand their decision. They may be tempted to shop a bit further and make a correct compromise based on knowledge.

All the rules of use and the warnings have been posted for many years. Andrey will likely re-post them near the grader when he gets the opportunity. This work is never finished, but this is how progress is made. :wavey: :wavey:
 

CaprineSun

Brilliant_Rock
Joined
Sep 30, 2010
Messages
579
Thanks Yssie. But that quoted post only told me why the stone got a grade of 2A, which I already knew. My question is to why one should not want a grade of 1A in a cut classification on a board where "cut is king" is a general consensus. Does a 2A stone have the same superior light performance of a 1A? Where is that explanation?

Yes, many consumers in the outside world may be fine with a less-than-ideal-cut stone (indeed, many are beautiful), but many PSers place cut above all else for performance-- including me. Why would I not want a top performing stone? This is why I feel like it is a useful tool for the picky PSers we are.

It certainly may not be as useful for the general population as well as for those who have seen their stone and immensely prefer certain less-than-ideal proportions (i.e. 60/60) over another "ideal" stone.
 

slg47

Ideal_Rock
Joined
Apr 4, 2010
Messages
9,667
*Twinkle*twinkle*|1309099987|2955374 said:
Thanks Yssie. But that quoted post only told me why the stone got a grade of 2A, which I already knew. My question is to why one should not want a grade of 1A in a cut classification on a board where "cut is king" is a general consensus. Does a 2A stone have the same superior light performance of a 1A? Where is that explanation?

Yes, many consumers in the outside world may be fine with a less-than-ideal-cut stone (indeed, many are beautiful), but many PSers place cut above all else for performance-- including me. Why would I not want a top performing stone? This is why I feel like it is a useful tool for the picky PSers we are.

It certainly may not be as useful for the general population as well as for those who have seen their stone and immensely prefer certain less-than-ideal proportions (i.e. 60/60) over another "ideal" stone.

60/60 is not less-than-ideal...it is just different. you can have a 60/60 with excellent light return.
 

druidtime

Rough_Rock
Joined
May 12, 2011
Messages
44
Oldminer,

Thanks for the development of the charts/tool. I know that had to take a while to make.

I originally stumbled upon the tool on your personal site via google while I was searching for my ER, and before I found PS.

It was a factor in my selection as it is very difficult to find good information regarding princess dimensions and cut quality.

I couldn't link you (the user here on PS) and your personal site together until you updated your signature here. Now I know its you.

With that, I believe I owe you a belated thank you for the info that guided my search. Much appreciated.

I believe you said in another thread that you have never seen anyone disappointed with a 1A or 1B stone. Future wife loves her 1A and she wants to thank you as well!
 

CaprineSun

Brilliant_Rock
Joined
Sep 30, 2010
Messages
579
slg47|1309103603|2955423 said:
*Twinkle*twinkle*|1309099987|2955374 said:
Thanks Yssie. But that quoted post only told me why the stone got a grade of 2A, which I already knew. My question is to why one should not want a grade of 1A in a cut classification on a board where "cut is king" is a general consensus. Does a 2A stone have the same superior light performance of a 1A? Where is that explanation?

Yes, many consumers in the outside world may be fine with a less-than-ideal-cut stone (indeed, many are beautiful), but many PSers place cut above all else for performance-- including me. Why would I not want a top performing stone? This is why I feel like it is a useful tool for the picky PSers we are.

It certainly may not be as useful for the general population as well as for those who have seen their stone and immensely prefer certain less-than-ideal proportions (i.e. 60/60) over another "ideal" stone.

60/60 is not less-than-ideal...it is just different. you can have a 60/60 with excellent light return.

OK... then change that to less than 1A grade vs 1A grade. I agree with you as I looked into 60/60's myself just a little while ago & posted about them.
 

Phasers

Rough_Rock
Joined
May 13, 2011
Messages
26
Ah cool, I plugged in my stone and got a 1B.

1234345567
Length:7.13
Width:7.18
Depth:4.43
Total Depth:61.91%
Table percent:57.8
Crown height:15
Girdle (from):Thin
Girdle (to):Slightly thick
Polish:Excellent / Very Good
Symmetry:Excellent / Very Good
Crown angle:35.7
Pavilion depth:43.1


Tab Percent: 1A
Crown Angle: 2A
Crown Height: 1A
Pavilion Depth: 1A
Girdle: 1B
Depth: 1A
Polish: 1A
Symmetry: 1A
TotalGrade: 1B

Makes me feel better. Stone is AGS Ideal 000. http://www.jamesallen.com/diamonds/J-SI1-Ideal-Cut-Round-Diamond-1363423.asp
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
9,741
The problem is not that a 1a stone won't be considered well cut by anyone knowledgeable- that huge problem with these type of systems are the false negatives. Reality has proven this to me, time and time again. Some of the most amazing, and well cut fancy shaped diamonds I've ever had the pleasure to see would be far from 1A if put on this grading scale.
Many people get the impression that if you want the best cut got for 1a. This thread proves- yet again- that the instructions given with this tool are woefully inadequate. twinkle twinkle's question goes to this. It's happened many times.

The terms "light performance" as well as "ideal cut" are commercial descriptions
How does light "perform"?
The cut of a diamond is not about achieving some maximum light return, rather about polishing a rough diamond into the most pleasing shape, retaining weight so as to be competitive price-wise- while designing a stone that does pleasing things with light.

I use the word "pleasing" as the matter of taste does come into play here.
For this reason both GIA and AGSL cut grading have no 'pinnacle"- rather, a plateau.
GIA's is wider.
AGSL has developed cut grades for some of the fancy shapes- which are rarely seen outside princess cut- which itself is pretty rare to find. There is no consensus on their results regarding fancy shapes.
What's better- Chunky ( large facets giving larger flashes), or Crushed ice ( many more bounces of light creating smaller flashes of light)?
It's really opinion- and the methods used to get either result in stones that are very different in proportions.

For example, crown height- sometimes a high crown/smaller table is desirable. But there are times a larger table and shallower crown height produce very nice results in the crushed ice look.
Or a shallow emerald cut that uses excellent cutting to take advantage of the steps and provide a deep look- and large surface area for their weight.


I think the effort put into the development is impressive. A constructive criticism would be to simplify the grades so that the "top" grade is more inclusive- much like GIA's or AGSL's methodology.
No matter how many times there's an asterisk telling people a 2a or 1b might actually be as well cut as a 1A, it does not matter. Somehow the impression remains that a 1a is "better" than a 2 a, when that's just not the case- or more accurately, the system cannot distinguish if the aspects it's using to assign this cut grade make the difference.
A 1a might be better than a 1b, or the 1b could actually be better than the 1a in some cases.
Or they might both be considered extremely well cut by masters in the trade.
 

CaprineSun

Brilliant_Rock
Joined
Sep 30, 2010
Messages
579
Rockdiamond|1309116676|2955532 said:
The problem is not that a 1a stone won't be considered well cut by anyone knowledgeable- that huge problem with these type of systems are the false negatives. Reality has proven this to me, time and time again. Some of the most amazing, and well cut fancy shaped diamonds I've ever had the pleasure to see would be far from 1A if put on this grading scale.
Many people get the impression that if you want the best cut got for 1a. This thread proves- yet again- that the instructions given with this tool are woefully inadequate. twinkle twinkle's question goes to this. It's happened many times.

The terms "light performance" as well as "ideal cut" are commercial descriptions
How does light "perform"?
The cut of a diamond is not about achieving some maximum light return, rather about polishing a rough diamond into the most pleasing shape, retaining weight so as to be competitive price-wise- while designing a stone that does pleasing things with light.

I use the word "pleasing" as the matter of taste does come into play here.
For this reason both GIA and AGSL cut grading have no 'pinnacle"- rather, a plateau.
GIA's is wider.
AGSL has developed cut grades for some of the fancy shapes- which are rarely seen outside princess cut- which itself is pretty rare to find. There is no consensus on their results regarding fancy shapes.
What's better- Chunky ( large facets giving larger flashes), or Crushed ice ( many more bounces of light creating smaller flashes of light)?
It's really opinion- and the methods used to get either result in stones that are very different in proportions.

For example, crown height- sometimes a high crown/smaller table is desirable. But there are times a larger table and shallower crown height produce very nice results in the crushed ice look.
Or a shallow emerald cut that uses excellent cutting to take advantage of the steps and provide a deep look- and large surface area for their weight.


I think the effort put into the development is impressive. A constructive criticism would be to simplify the grades so that the "top" grade is more inclusive- much like GIA's or AGSL's methodology.
No matter how many times there's an asterisk telling people a 2a or 1b might actually be as well cut as a 1A, it does not matter. Somehow the impression remains that a 1a is "better" than a 2 a, when that's just not the case- or more accurately, the system cannot distinguish if the aspects it's using to assign this cut grade make the difference.
A 1a might be better than a 1b, or the 1b could actually be better than the 1a in some cases.
Or they might both be considered extremely well cut by masters in the trade.

Thanks RockDiamond! :appl:
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
27,292
*Twinkle*twinkle*|1309099987|2955374 said:
Thanks Yssie. But that quoted post only told me why the stone got a grade of 2A, which I already knew. My question is to why one should not want a grade of 1A in a cut classification on a board where "cut is king" is a general consensus. Does a 2A stone have the same superior light performance of a 1A? Where is that explanation?

Yes, many consumers in the outside world may be fine with a less-than-ideal-cut stone (indeed, many are beautiful), but many PSers place cut above all else for performance-- including me. Why would I not want a top performing stone? This is why I feel like it is a useful tool for the picky PSers we are.

It certainly may not be as useful for the general population as well as for those who have seen their stone and immensely prefer certain less-than-ideal proportions (i.e. 60/60) over another "ideal" stone.


Just to be redundant and iterate what slg and RD have already said - a 60/60 is not less-than-ideal. Just different. A different sort of ideal.

The AGA tool has one very specific set of proportions that constitutes its 'best' grade - that set of proportions translates into a very specific aesthetic.

Many people wouldn't note a difference between the 1A look, a shallower look, a deeper look... many will. My personal preference falls outside the 1A range - anecdotal evidence that people *do* have a variety of preferences. It is truly impossible to pin down all these preferences into one specific range, one specific aesthetic. 1A will be a general crowd-pleaser, and 1A stones will be lovely, but so will other stones - the problem, of course, is that it instinctively makes you feel better about your lovely stone if it gets a higher 'score' on any tool, regardless of what that tool is actually meant to be used for, what that tool is really designed to measure or indicate, what the tool's creator's preferences are...

Dilemma! I think the AGA tool is a nifty thing to have in one's arsenal - so long as one really understands that there is no such thing as a one-size-fits-all pinpoint ideal for diamond proportions (and frankly I have no doubt there never will be, we can optimize what the diamond is *doing* all we like but we'll never equalize how different eyes perceive what they see, and what those different eyes prefer).

ETA - sorry if I expressed that poorly earlier. People using any tool/programme/design without fully understanding uses and limitations drives me absolutely nuts, and the more complicated the tool the more likely it is to be misused!
 

CaprineSun

Brilliant_Rock
Joined
Sep 30, 2010
Messages
579
Happened to be checking out another stone and what it would be on the different PS tools and came upon this thread again.

Thanks to Yssie, Rock Diamond & the other posters here, I now better understand how to use it and its limitations. I've learned so much being here.

What I can say about the AGA tool now is that if the results are consistent with what you are getting from other tools, HCA, IS, H&A viewer, the AGA tool is helping to confirm (whether good or bad). If there are inconsistencies i.e. good HCA, bad AGA score, then further investigation may be needed--- ASET, IS & especially with your own eyes.
 
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