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1) Help with numbers needed 2) AGS000 with 3.4 HCA

eyvind

Rough_Rock
Joined
Sep 27, 2015
Messages
11
Hi guys, I have 2 questions. Unrelated.

1) Would anyone be so kind to have a look at this numbers? Please tell me what you think. Much appreciated.

depth 60.4%
table 59%
CA 33.5
PA 40.8
SL 50%
LGF 75%
crown height 13.5%
pavilion depth 43%
girdle 4% medium-slightly thick

2) I've read that if a stone is AGS000, the HCA score is less important. Should I ignore 3.4 HCA score in this case?
 

ecf8503

Ideal_Rock
Premium
Joined
Feb 14, 2005
Messages
4,096
I'm getting an HCA of 1.3 with those numbers. And AGS 0 trumps HCA anyway.
 

eyvind

Rough_Rock
Joined
Sep 27, 2015
Messages
11
ecf8503- I know, these are two different stones (I should make two different topics- sorry for misleading).
But how is it possible that AGS000 get's 3.4 HCA score? I mean, either a stone has a good light performance or not. Numbers for ags: table 55.9% depth 62,7% CA 34.7 PA 41.2
 

MissGotRocks

Super_Ideal_Rock
Premium
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Jun 23, 2005
Messages
16,416
eyvind|1443828327|3934270 said:
ecf8503- I know, these are two different stones (I should make two different topics- sorry for misleading).
But how is it possible that AGS000 get's 3.4 HCA score? I mean, either a stone has a good light performance or not. Numbers for ags: table 55.9% depth 62,7% CA 34.7 PA 41.2

The HCA dings this stone for depth and pavilion angle. Both of those numbers are out of ideal range and the HCA weeds out possible bad performers. However, AGS apparently thinks this stone is ideal in light performance.
 

pyramid

Ideal_Rock
Premium
Joined
Nov 10, 2002
Messages
4,607
Because AGS software scans the actual diamond before producing the report and variations in minor facets can mean the diamond performs better than a diamond graded on a simple wire frame of just main facet angles. I believe I read the star facet length percentage and the upper pavilion angles are what make the difference. Hopefully one of the experts could confirm?
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,340
The thing is this ...

While the AGS cut grading system is the strictest system it also has its boundaries which can fall on what many conservative folk feel is a little too liberal. For example a 34.7/41.2 may make AGS Ideal but in some of the vendors personal grading systems here it wouldn't make their top tier brand.

Bottom line ... AGS 0 does not equal a PS top brand and in this scenario doesn't even qualify for an HCA good stone either and I'd agree with that assessment.

Peace,
Rhino
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,340
Here's a potential ASET assuming perfect 3 dimensional symmetry which it likely does not have.

The pale whites under the table are indicative of leakage occurring and will diminish brightness and fire and demonstrates what I'm talking about.

If you have questions feel free to ask.

Kind regards,
Rhino

_34726.jpg
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,340
Rhino|1443834651|3934295 said:
The thing is this ...

While the AGS cut grading system is the strictest system it also has its boundaries which can fall on what many conservative folk feel is a little too liberal. For example a 34.7/41.2 may make AGS Ideal but in some of the vendors personal grading systems here it wouldn't make their top tier brand. Certainly not my own.

Bottom line ... AGS 0 does not equal a PS top brand and in this scenario doesn't even qualify for an HCA good stone either and I'd agree with that assessment.

Peace,
Rhino
 

eyvind

Rough_Rock
Joined
Sep 27, 2015
Messages
11
Thanks very much everyone for your answers- especially to you, Rhino. I do appreciate it a lot.
Can I also have your opinion on the first diamond? I mean, this one:

1.51 ct
7.39 x 7.42 x 4.47
depth 60.4%
table 59%
CA 33.5
PA 40.8
SL 50%
LGF 75%
crown height 13.5%
pavilion depth 43%
girdle 4% medium-slightly thick

I'm having a hard time trying to decide whether to go for it, or to keep looking for a smaller stone, but closer to Tolkowsky ideal. Will it perform good? Is it a typical 60/60 stone?
 

gr8leo87

Shiny_Rock
Joined
Apr 24, 2015
Messages
381
HCA penalizes deeper pavilion angles in steeper crown angles. Try changing the PA 41.2 to 40.8 and u will see all the number changing. HCA and AGS cut grading system are two different things.

Consider a stone with steep crown angles at 36 and slightly shallow PA at 40.4, it might receive <2 HCA score and an AGS Ideal. But will not get a GIA excellent? Is GIA grading bad? No, not at all. All have their own tolerances.

A stone with Pavillion Depth shallower than 43 will not receive Excellent cut grade from HRD but is within the ideal and Ex range of AGS and GIA respectively.
 

gr8leo87

Shiny_Rock
Joined
Apr 24, 2015
Messages
381
eyvind said:
Thanks very much everyone for your answers- especially to you, Rhino. I do appreciate it a lot.
Can I also have your opinion on the first diamond? I mean, this one:

1.51 ct
7.39 x 7.42 x 4.47
depth 60.4%
table 59%
CA 33.5
PA 40.8
SL 50%
LGF 75%
crown height 13.5%
pavilion depth 43%
girdle 4% medium-slightly thick

I'm having a hard time trying to decide whether to go for it, or to keep looking for a smaller stone, but closer to Tolkowsky ideal. Will it perform good? Is it a typical 60/60 stone?
Indeed it's a 60/60 stone. And it's much better than common 6060s. It has a reasonable crown height and angle. And a reasonable Pavillion angle.

A typical 60 60 looks more like this

Depth : 60 or around
Table : 60 or around
Crown height : 12.5 or around
Angle: 32 or around
Pavillion Depth : 43.5 or deeper.
Angle: 41.2 or deeper.

Cheers
 

eyvind

Rough_Rock
Joined
Sep 27, 2015
Messages
11
Thank you very much, gr8leo87. Basically, my dilemma here is like this: I can get 60/60 1,51ct or 1.25ct Tolk ideal cut, because of limited budget. 0.25 ct is quite a difference.
I'm not sure if the pavilion angle in 60/60 stone shouldn't be steeper (due to the rule shallower crown - steeper pavilion and vice versa). Does anyone can tell what are ideal numbers for 60/60 stone? (perhaps I should start new topic with this).
 

gr8leo87

Shiny_Rock
Joined
Apr 24, 2015
Messages
381
eyvind said:
Thank you very much, gr8leo87. Basically, my dilemma here is like this: I can get 60/60 1,51ct or 1.25ct Tolk ideal cut, because of limited budget. 0.25 ct is quite a difference.
I'm not sure if the pavilion angle in 60/60 stone shouldn't be steeper (due to the rule shallower crown - steeper pavilion and vice versa). Does anyone can tell what are ideal numbers for 60/60 stone? (perhaps I should start new topic with this).
Your 60-60 have pretty reasonable numbers for a 6060.

You should look at both the stones side by side and select what you like. Numbers do not tell the whole story.

Cheers
 

eyvind

Rough_Rock
Joined
Sep 27, 2015
Messages
11
I know, but it's not possible while shopping online :(sad
 

FancyIntense

Shiny_Rock
Joined
Mar 3, 2014
Messages
278
Why is the choice between these two stones only? You said you are shopping online, check out Rhino's site Good Old Gold for the heck of it.

Are you willing to let some experts point you to some excellent candidates instead? They will look for excellent diamonds in your price range. :angel:
 
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