See the new tool in the "TOOLS" section

[oldminer]

https://www.pricescope.com/GA_NAJA_Cut_Class_Grader

I am really pleased that Pricescope has seen fit to add this long used screening tool to the arsenal of useful items brought to consumers and the trade. Although it has been the subject of many years of work, it is not the perfect way to select a diamond, but it may prove helpful to many of you.

I want to call to your attention that AGS0 Princess cuts tend to get a cut grade 2 using this tool and they are extremely beautiful stones. There are few standard cut princess cuts which would grade at a 1 grade, but those I have seen looked great to me when I examined them. However, the AGS0 is the special cut princess that has caught on with those who want a fine lab to grade a fine stone. So, don't screen out AGS0 stones based on not getting a 1 grade in this system. It was not put here to hurt vendors or to misinform consumers. The AGS0 princess is a special design which work very well with light, but tends to be a bit beyond the 1 range on the AGA/NAJA automated tool.

Happy shopping!

 

[minmin001]

Any guide line on how to read it? like what does 2B mean? I pluged a random AGS000 diamond I found online and it came out total grade 4A. what does that suppose to mean?

 

[oldminer]

You must have entered the information improperly to have gotten such a grade on an AGS000 diamond. Here's a link to the charts on Pricescope which explain the various grades. This link is for round diamonds:
https://www.pricescope.com/wiki/diamonds/diamond-grading-chart-round

Look under "KNOWLEDGE" and find all 4 charts. 1A is the very top range and 4B is the lowest range.

 

[Gibson486]

Yay...mine scored 1A...

I swear, I have seen that chart somewhere else before. I think USAcerted diamonds sends you that chart when you email them....oh well, it's always nice to have the stuff automated.

 

[minmin001]

here is the info for the diamond. still got 4A as total grade
Shape: Round
Carat weight: 1.01
Cut: Hearts & Arrows Ideal
Color: D
Clarity: SI1
Certificate: AGS

Depth: 61.9%
Table: 55.7%
Polish: Ideal
Symmetry: Ideal
Girdle: Thin to slightly thick
Culet: None
Fluorescence: Negligible
Measurements: 6.43*6.45*3.99
Crown Angle: 34.6
Crown %: 15.30
Pavilion Angle: 40.7
Pavilion %: 43.00

 

[yssie]

here is the info for the diamond. still got 4A as total grade
Shape: Round
Carat weight: 1.01
Cut: Hearts & Arrows Ideal
Color: D
Clarity: SI1
Certificate: AGS

Depth: 61.9%
Table: 55.7%
Polish: Ideal
Symmetry: Ideal
Girdle: Thin to slightly thick
Culet: None
Fluorescence: Negligible
Measurements: 6.43*6.45*3.99
Crown Angle: 34.6
Crown %: 15.30
Pavilion Angle: 40.7
Pavilion %: 43.00

I get 1A - first time I plugged angles into the percent boxes and it was obviously far lower

 

[yssie]

congrats Oldminer

I'm glad PS has included just the tool, no lookup charts to muddy the waters, and I hope new consumers will use it it in the spirit it is intended.


ETA: Some null case checking - or at the very least add a warning regarding impossible combinations, this is important IMO. Changing crown height (but not angle) on minmin's stone to 30.3 lowers the cut grade... also results in a physically impossibly configured stone, but a new consumer would have no reason to suspect this, and thus suspect his inputs are all off

 

[oldminer]

Yssie; I agree that no null conditions are included. Since a consumer is supposed to input only diamonds which actually exist, they will only get possible results and not false results on stones that would be physically impossible to cut. People who put degrees in where percentages are supposed to be entered will not get proper results, either. I believe Andrey is considering how to handle either placement or removal of the charts. Maybe he'd appreciate some objective input although we know most dealers would prefer not to see any data from any screening tool or chart. Sometimes this position of buy what you like instead of buy what is graded as "the best" does make sense. Most of the time we make compromises, but I believe it is very useful to have some handle on the extent of compromise being taken. There are many beautiful 2B to 3B cut diamonds in circulation which are happily owned or being offered for sale. A screening tool that allows you to understand what your choice means relative to alternative choices is something that I have always thought had a useful place at the consumer level.

 

[minmin001]

oh I see what I did, I enter the depth into the crown height % lol...
great useful tools~ thank you

 

[yssie]

Yssie; I agree that no null conditions are included. Since a consumer is supposed to input only diamonds which actually exist, they will only get possible results and not false results on stones that would be physically impossible to cut. People who put degrees in where percentages are supposed to be entered will not get proper results, either. I believe Andrey is considering how to handle either placement or removal of the charts. Maybe he'd appreciate some objective input although we know most dealers would prefer not to see any data from any screening tool or chart. Sometimes this position of buy what you like instead of buy what is graded as "the best" does make sense. Most of the time we make compromises, but I believe it is very useful to have some handle on the extent of compromise being taken. There are many beautiful 2B to 3B cut diamonds in circulation which are happily owned or being offered for sale. A screening tool that allows you to understand what your choice means relative to alternative choices is something that I have always thought had a useful place at the consumer level.

I see what you are saying re. garbage in garbage out, but I submit that the output from Garry's HCA tool is easier to interpret - in that there is no confusion as to whether 1A is realistically an achievable goal, whether to "settle" for 1B or 2A or 2B and "just how bad is it"... and yet we see the HCA misused every day! People don't usually use tools the way they're supposed to, I've found - a warning in red at the top of the page to enter numbers exactly as they appear on the report/scan, and to double-check entries, wouldn't detract from the tool, but just maybe it'll make new users give inputs the once over before freaking out that their branded H&A is a 4B...

Well, that's in my opinion of course!

 

[oldminer]

No doubt Andrey is reading this thread and will take some action that is appropriate. I don't disagree with advising caution in using such tools in a casual or improper way and the relying on them. the entire process of buying a diamond in a technical manner is a very precise operation. If you want to buy a diamond casually and just select one you like in a store, you don't need any tools but your wallet and your eyes. It would be an even better tool if putting numbers in that were impossible combinations would result in a "not possible" grade. I just never thought about doing this in the 1990's when I was working on the charts and automated system. We only used it on actual diamonds and never used it like a toy. If someone wants to re-write the code it would be an improved version for today's more digital era.

 

[yssie]

Oldminer what language?
I'll have some time soon.

 

[MissGotRocks]

Thanks for pointing out this tool - my stone got all 1A's! Nothing like a little science to confirm what your eyes see!

Thanks again!

 

[PCMusicGuy]

Very neat little tool. My AGS princess was getting 4A until I entered the correct crown height. Then it was 1A everywhere.

 

[oldminer]

What users and Pricescopers whould keep in mind is this tool was created in the 1990's BEFORE AGS even had a laboratory and long before GIA even gave detailed measurements of diamond components on their reports. The fact that nearly all finely cut diamonds graded by major labs in their newest reports fit into this system based on their newer research confirmed that my own efforts had gone in the correct direction long before the digital image analysis of performance was in the diamond market. Any exception, such as the AGS0 Princess cut, happen because a very wide set of parametrs can created beautiful and well performing diamonds, but the cutters must see certain levels of efficiency of rough retained weight, and a willing market must be created that will accept the particular cut. AGS has done a great job in creating this Branded cut and getting it accepted by a sufficient number of shoppers and cutters. No doubt, had I been able to have seen such "special" cutting back when I was many the data charts for princess cuts, I could have included AGS0 princess cuts into the system in some useful way. Likely as not, there are many other cuts for rounds and fancy shapes that would perform very well outside of the AGA 1A-1B grades, but no one cuts them and no consumer is seeking them in any meaningful way. That could change, but we don't know when or if it will at all.

 

[Cehrabehra]

Hey! I also note that they got the shape selector on there - that's one of my favorite tools! Congrats!!

 

[Garry H (Cut Nut)]

For the record I 'met' Dave in the mail (not email) world about 24 years ago when I asked his permission to use his charts in lectures to the Australian Gemmology diamond course.

 

[Rockdiamond]

The cut grade tool is a very misleading tool without a proper instruction manual
I strongly believe this type of tool hurts consumers more than assisting them

 

[CaprineSun]

This is great! I was looking at a stone EGL USA "ideal" cut , but had 1.7 HCA score. Saw it in person with idealoscope and looked much better than other stones I saw-- (but then again, I'm no expert, just a novice). I forgot to take a pic of it though.

On this tool, it receives a 2A grade. Hit for the crown angle & height= both 2A grade.--- Far from the ideal I'm looking for, so I'll pass.

Thanks!

ETA: And I really appreciate the extra tools we get as consumers on this board to make a purchase of a stone we truly want. Especially if it's not AGS graded. It might not be as simple as the HCA, but it's nothing that can't be fixed with a double-check & careful reading, IMO.

 

[yssie]

This is great! I was looking at a stone EGL USA "ideal" , but had 1.7 HCA score. Saw it in person with idealoscope and looked much better than other stones I saw-- (but then again, I'm no expert, just a novice). I forgot to take a pic of it though.

On this tool, it receives a 2A grade. Hit for the crown angle & height.--- Far from the ideal I'm looking for, so I'll pass.

Thanks!

And... ExhibitA of exactly the trouble that I, you, Oldminer, and everyone else was anticipating.

There's NOTHING wrong w/ a 2A stone. But, naturally, most consumers simply don't have the patience to read through the documentation and understand that there's no point in seeking that pinpoint combination that is 1A...


I agree with RD - without appropriate warning and terms of use (appropriate meaning a couple of sentences in bright red at the top of the page that users can't help but read) it is too easy to misuse, and to lead to misleading rather than helpful observations about potential stones.

 

[Rockdiamond]

Exactly my point yssie
I know it was designed with good intentions but there needs to be a far easier to understand instruction guide

 

[CaprineSun]

This is great! I was looking at a stone EGL USA "ideal" , but had 1.7 HCA score. Saw it in person with idealoscope and looked much better than other stones I saw-- (but then again, I'm no expert, just a novice). I forgot to take a pic of it though.

On this tool, it receives a 2A grade. Hit for the crown angle & height.--- Far from the ideal I'm looking for, so I'll pass.

Thanks!

And... ExhibitA of exactly the trouble that I, you, Oldminer, and everyone else was anticipating.

There's NOTHING wrong w/ a 2A stone. But, naturally, most consumers simply don't have the patience to read through the documentation and understand that there's no point in seeking that pinpoint that is 1A... more reason to add the warning & simplified terms of use in red at the top of the tool...

Thanks so much for pointing this out, but are you saying a 2A would perform just as well as a 1A? I read the chart provided. Why wouldn't one want a 1A grade?

What documentation are you speaking of (besides the chart)? Still learning....and have the patience to read it.

 

[Mayk]

So this begs a question of a newbie. I put my stats in on my AGS000 stone which has an older certificate 4/24/03 and I get 1B. Does that mean today my stone might not be a 000? I will say I am not certain I entered the girdle correctly. The min/max is 1.0% - 1.7%. Adjusting it didn't seem to change it much. My stone AGS 4004304 RB 1.300 cts.


1234345567
Length:6.95
Width:7.00
Depth:4.37
Total Depth:62.65%
Table percent:56.0
Crown height:15.6
Girdle (from):Slightly thin
Girdle (to):Medium
Polish:Excellent / Very Good
Symmetry:Excellent / Very Good
Crown angle:35.4
Pavilion depth:43.4

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

Stone Shape

 

[yssie]

This is great! I was looking at a stone EGL USA "ideal" , but had 1.7 HCA score. Saw it in person with idealoscope and looked much better than other stones I saw-- (but then again, I'm no expert, just a novice). I forgot to take a pic of it though.

On this tool, it receives a 2A grade. Hit for the crown angle & height.--- Far from the ideal I'm looking for, so I'll pass.

Thanks!

And... ExhibitA of exactly the trouble that I, you, Oldminer, and everyone else was anticipating.

There's NOTHING wrong w/ a 2A stone. But, naturally, most consumers simply don't have the patience to read through the documentation and understand that there's no point in seeking that pinpoint that is 1A... more reason to add the warning & simplified terms of use in red at the top of the tool...

Thanks so much for pointing this out, but are you saying a 2A would perform just as well as a 1A? Absolutely, definitely, indubitably, certainly, surely... I read the chart provided. Why wouldn't one want a 1A grade? Because it excludes a whole lot of *beautiful* proportions - 60/60 types, for example, that many people actively prefer. Because it's a pinpoint ideal - and not everyone agrees with the pinpoint, not everyone finds that pinpoint most beautiful. There's nothing wrong with striving for 1A - if that's what your eyes prefer. There's everything wrong with striving for 1A for the sake of striving for 1A.

What documentation are you speaking of (besides the chart)? Still learning....and have the patience to read it.
I can't for the life of me find the explanation page. I will keep digging for it, unless Oldminer comes in or someone else has the direct linke... Some articles here http://www.gemappraisers.com/articles.htm incl one on AGA and HCA

ETA: old post that includes that info -

Here are the rules which are coded into the grader as well as further information on judging fancy shaped diamonds:

Rules For Determining "Overall" Cut Grade.
1A grade: All characteristics are best when 1A, but may include a single 1B characteristic. You pay a premium for this cut and you should insist on getting exactly what you are paying for.

1B grade: All characteristics need to be all 1B or 1A to 2B. Only a single class 2 characteristic is permitted. The class 2 characteristic should be within 2% or 2 degrees of the 1B characteristic.
2A grade: All characteristics need to be 2A or 1A thru 2B. Only a single 2B parameter is permitted and it must be within 2% or 2 degrees of the 2A characteristic. (crown angle degree rounds only)

2B grade: All characteristics need to be all 2B or 1A thru 3A. Only a single 3A characteristic is permitted and the 3A characteristic cannot be a very thick girdle or more than 1 degree too shallow a crown angle. The 3A characteristic must be within 2% or 1 degree of the 2B characteristic. (crown angle degree rounds only)

3A grade: A stone may be all 3A or 1A thru 4A. Any characteristics of 4A must be within 2% or 1 degree the 3B characteristic. More than a single 4A characteristic and the stone cannot grade 3A. An overall class 4 girdle thickness cannot grade 3A overall. An overall girdle thickness is NOT determined by a single thin or thick area of a girdle. "Overall" has a meaning equivalent to "the major portion." (crown angle degree rounds only)

3B grade: As stone may be all 3B or 1A thru 4B. Any single characteristic of grade 4B must be within 2% or 1 degree of the 4A measurement. Only one class 4 characteristic permitted. Stones with class 4 extremely thick or extremely thin over all girdles may not be graded overall 3B. (crown angle degree rounds only)

4A grade: A stone may be all 4A or 1A thru 4B. Only two 4B characteristics are permitted at most. (crown angle degree rounds only)

4B grade: Is all 4B or may be any combination from 1A thru 4B. Stones with more than two 4B characteristics are automatically 4B. ________________________________________
Specialty Cuts: This may include many forms of BRANDED DIAMONDS.
There are diamonds that do not conform to the classic shape cut parameters and must be considered on an individual basis.
ONE CANNOT GRADE UNUSUAL CUT DIAMONDS SOLELY ON ARBITRARY PARAMETERS. EXPERIENCE IN EXAMINING DIAMONDS FOR EFFECTIVE AND PRECISE CUTTING IS REQUIRED FOR CUTS NOT COVERED IN THE FOUR CHARTS OF TYPICAL STANDARD CUT DIAMONDS.

Things to keep in mind for the finest fancy shapes:
FANCY IDEAL CUTS
All ideal cuts must look “beautiful”. Beauty is initially achieved through proper outline, careful facet arrangement, and facet matching. It is furthered by proper cut craftsmanship. The parameters of cut for relative show of size and for durability must be observed. Lastly, all ideal cuts exhibit relatively high, yet balanced amounts of brilliancy, scintillation and intensity. Fire may also be considered as an element of appearance in certain instances where it is featured.
Needle-like shapes, high or dropped shoulders, bulging or flat sides, asymmetry, overly deep or too shallow all contribute to lack of beauty. Don’t blind your self to the obvious. Pear, marquise, oval and heart shaped diamonds have a range of best length to width ratio. Rectangular and square stones don’t have a length to width requirement, they do require 90 degree corners except in unusual circumstances or in special cuts.
Personal preference for a particular, odd shape, should have no effect on the grading for light performance or symmetry, but such a shape might fall out of the finest, commonly accepted, arrangement for beauty, salability or durability. This is a choice an informed consumer may choose to make, but it is not acceptable for a gemological lab or a dealer to provide incorrect data about an odd stone being “ideal” when it does completely and truly fit the category.
An Ideal Cut, whether round or fancy shaped, is the essence of beauty and proper cutting without compromise. It is tempting to promote stones that approach this goal but miss it as “ideal”, but it is not worth the damage to the industry to attempt such marketing.

 

[yssie]

So this begs a question of a newbie. I put my stats in on my AGS000 stone which has an older certificate 4/24/03 and I get 1B. Does that mean today my stone might not be a 000? I will say I am not certain I entered the girdle correctly. The min/max is 1.0% - 1.7%. Adjusting it didn't seem to change it much. My stone AGS 4004304 RB 1.300 cts.


1234345567
Length:6.95
Width:7.00
Depth:4.37
Total Depth:62.65%
Table percent:56.0
Crown height:15.6
Girdle (from):Slightly thin
Girdle (to):Medium
Polish:Excellent / Very Good
Symmetry:Excellent / Very Good
Crown angle:35.4
Pavilion depth:43.4

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

Stone Shape

Your stone is *fine*. AGS0 and AGA are disparate tools, developed by different groups/people, with different requirements and ranges for various grades.

Ed* deleted double paste

 

[Mayk]

Thank you Yassie. I know it's beautiful. There is always so much discussion about labs and the evolution of refinement of measuring stones. It is so interesting.

 

[stone-cold11]

So this begs a question of a newbie. I put my stats in on my AGS000 stone which has an older certificate 4/24/03 and I get 1B. Does that mean today my stone might not be a 000? I will say I am not certain I entered the girdle correctly. The min/max is 1.0% - 1.7%. Adjusting it didn't seem to change it much. My stone AGS 4004304 RB 1.300 cts.


1234345567
Length:6.95
Width:7.00
Depth:4.37
Total Depth:62.65%
Table percent:56.0
Crown height:15.6
Girdle (from):Slightly thin
Girdle (to):Medium
Polish:Excellent / Very Good
Symmetry:Excellent / Very Good
Crown angle:35.4
Pavilion depth:43.4

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

Stone Shape

Probably will not get an AGS0 in cut performance if you sent it in for a regrade. Your AGS0 is based on proportions, before the present performance based grading system, slightly too deep in the pavilion for that crown angle. lower half might compensate for it, but that data is not available on the old report.

 

[Mayk]

What happens to performance when it's too deep?

 

[stone-cold11]

Light leakage.

More reading.
https://www.pricescope.com/journal/laboratory_cut_grades_what_report_doesn’t_show

 

[Mayk]

Thank you Stonecold. Very interesting. Would be very interested at some time to have my stone revisit the AGS lab.