Crown and Pavilion

[tunis]

I'm looking at a stone with a crown angle of 33.9 and a pavilion of 41. It gets a 1.3 on the HCA but my concern is that I've heard that crown angles of 34.7-9 seem to be the sweet spot - at least for WF ACA. What are the ramifications of this combo (c 33.9, p 41), or is this too subjective to really speculate?

Thanks,

Tunis

 

[stone-cold11]

There is no sweet spot. It is an interplay between table size, crown and pavilion angles. Which the HCA shows.

Edt:
What is the table size and depth, I am curious.

 

[tunis]

The depth is 61.4 and the table 55.3. This is an AGS000 stone...

Tunis

 

[MissGotRocks]

It should be a beautiful stone!

 

[stone-cold11]

ya, it should be a beautiful stone, no worry.

 

[Regular Guy]

Date: 10/26/2008 6:12:59 PM
Author: Stone-cold11
There is no sweet spot. It is an interplay between table size, crown and pavilion angles. Which the HCA shows.

Stone-cold,

This is a controversial, and lately even more, a nuanced position.

First...for those of us who on balance accept 0 - 2 for the HCA, that could be true...but you yourself I believe have quoted that that formula should be applied to the intended function...with more shallow crowns being reserved, as described, for pendants.

And so, several here are fond of quoting angle ranges.

Then, there's the AGS pedigree. But...the quote of this being AGS000 made me at least suspicious. Maybe it IS the older format (newer I think aren't often quoted that way...but regardless...running it through the HCA, and reading the cross hairs for location...it is at a minimum consistent with a "thumbs up" under the newer rating.

For my money, I've been convinced enough that a 3 D scan under the new system is a strong predictor of a swell stone.

Meeting those boxes as defined under the HCA chart, anywhere in the boxes for the AGS0...and a 3D map (giving 0 for light performance) would represent a very green light.

Go to either gold or 2 D or the old system (still with precise measures), and I suppose you'll be only marginally less safe until you add in an idealscope.

Reference only the HCA, without having had the benefit of AGS measures...and you're marginally less again assured of a well cut diamond until you add reflector technologies...although Jonathan at GOG will be happier with 38 more tests, I'm sure.

Just some additional reactions for you....

 

[stone-cold11]

IMHO, Ira, it is still an interplay of the variables and nuanced with 3-D symm, brillianteering, star facet and LGF angles.

The crown angle stated is far from shallow anyway, and pendant stones are more of the band of angles relationship below the AGS0 range than a particular cut-off crown angle from what I understand.

 

[Regular Guy]

Stone,

Somehow I think we''re talking past each other.

Except...it may be helpful to note...where they exist...when you have "protections" by way of thresholds.

For example...I think that, when an AGS0 is attained for light performance, you needn''t cipher the details...they''re all non-pendant types. If you don''t agree with that...I''d like to understand the example.

 

[tunis]

Here''s the stone that I''m referencing:

http://www.goodoldgold.com/diamond.php?d=4175&shape=1&ctMin=1.5&ctMax=1.8&clarity=48&color=64&priceMin=10000&priceMax=13000&resultsColumns=268435471&singleResult=1

Please let me know how you think this performs compared to other top superideals you''ve seen.

Thanks,

Tunis

 

[coatimundi_org]

Um...Yeah! It looks like an amazing stone!

 

[tunis]

So yes, this is obviously a nice stone. But I''m just a novice and so I am wondering where (if at all) this stone falls short?

Thanks experts,

Tunis

 

[Fly Girl]

Let's see. ISEE2 stone, Helium report shows all EXs, AGS 0 cut, VS clarity, GEM EX all in highest range. I recently got a stone with those specs from GOG, and it is AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Reserve it now, before it's gone!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ETA: Let me add that the J color brings down the price to make it more affordable, and, in my humble opinion, you compromise very little on color. That gives you a great value.

 

[Regular Guy]

Date: 10/26/2008 11:00:02 PM
Author: Fly Girl
Let''s see. ISEE2 stone, Helium report shows all EXs, AGS 0 cut, VS clarity, GEM EX all in highest range. I recently got a stone with those specs from GOG, and it is AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Reserve it now, before it''s gone!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Don''t you think it would be better if it were here?

 

[Fly Girl]

Date: 10/26/2008 11:03:00 PM
Author: Regular Guy

Date: 10/26/2008 11:00:02 PM
Author: Fly Girl
Let''s see. ISEE2 stone, Helium report shows all EXs, AGS 0 cut, VS clarity, GEM EX all in highest range. I recently got a stone with those specs from GOG, and it is AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Reserve it now, before it''s gone!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Don''t you think it would be better if it were here?

LOL

 

[tunis]

Flygirl, what does ISEE2 stone mean?

Tunis

 

[stone-cold11]

Ira, agreed. AGS0 stone is never a pendant stone.

 

[Lorelei]

Date: 10/27/2008 5:05:53 AM
Author: Stone-cold11
Ira, agreed. AGS0 stone is never a pendant stone.

There are members here who have AGS0 stones for pendants. They may not be considered to be the more ' shallow pendant types' but they certainly can be pendant stones.

 

[stone-cold11]

Date: 10/26/2008 11:34:30 PM
Author: tunis
Flygirl, what does ISEE2 stone mean?

Tunis

One of the excellent diamond cutting brands around. Their stones are always top grade, similiar to ACA of WF and CraftedbyInfinity stones. They mark their stones with a special symbol which you can see in the AGS report. GOG will probably have it''s birth certificate too.

 

[Ellen]

As others have said, this is an excellent cut stone, you can''t go wrong. No worries.

 

[Fly Girl]

Date: 10/27/2008 5:11:42 AM
Author: Stone-cold11

Date: 10/26/2008 11:34:30 PM
Author: tunis
Flygirl, what does ISEE2 stone mean?

Tunis

One of the excellent diamond cutting brands around. Their stones are always top grade, similiar to ACA of WF and CraftedbyInfinity stones. They mark their stones with a special symbol which you can see in the AGS report. GOG will probably have it''s birth certificate too.

Exactly. The special symbol on the cert confirms the ISEE2, but what I love about these is the DiamXray photo. ISEE2s have a distinctive, extra sharp set of Xs (crosses) in the very center. When I see those, I check, and more often than not, it''s an ISEE2. Superb cut on that diamond, Tunis. It will be a sparkler.

 

[tunis]

My sincere thanks to everyone who helped educate me on this thread.

Tunis

 

[tunis]

Okay, one final question:

Is there any reason to think this stone falls short of the cut quality of WF ACA?

I guess this is what I was really asking from the get-go...

Thanks,

Tunis

 

[stone-cold11]

Date: 10/27/2008 1:37:32 PM
Author: tunis
Okay, one final question:

Is there any reason to think this stone falls short of the cut quality of WF ACA?

I guess this is what I was really asking from the get-go...

Thanks,

Tunis

Nope. This stone should be up there with ACA quality.

 

[Ellen]

Date: 10/27/2008 1:37:32 PM
Author: tunis
Okay, one final question:

Is there any reason to think this stone falls short of the cut quality of WF ACA?

I guess this is what I was really asking from the get-go...

Thanks,

Tunis

Nope. I happen to own an Isee2 with very similar numbers. I also own ACA studs. They are equally beautiful. Now hop on that stone!

 

[Lorelei]

Date: 10/27/2008 2:15:26 PM
Author: Ellen

Date: 10/27/2008 1:37:32 PM
Author: tunis
Okay, one final question:

Is there any reason to think this stone falls short of the cut quality of WF ACA?

I guess this is what I was really asking from the get-go...

Thanks,

Tunis

Nope. I happen to own an Isee2 with very similar numbers. I also own ACA studs. They are equally beautiful. Now hop on that stone!

Ellen knows!!!

 

[tunis]

Thanks everyone for your knowledge, and more importantly your willingness to share it...

Tunis

 

[Ellen]

You''re welcome tunis. Let us know how it goes!

 

[Lorelei]

Date: 10/27/2008 3:02:48 PM
Author: Ellen
You''re welcome tunis. Let us know how it goes!

Ditto Tunis, keep us posted!

 

[tunis]

Will do, Lorelei,

What is the significance, if any, to the HCA that gives this a 1.3 but gives the following rating:

ex, ex, vg, vg

Many other AGS0 stones I've seen register

ex, ex, ex, vg

Is the vg for scintillation due to the crown and pav angle combinations, and does this really matter in view of everything else we know about the stone?

So many questions...

Tunis

 

[Lorelei]

Date: 10/27/2008 3:23:00 PM
Author: tunis
Will do, Lorelei,

What is the significance, if any, to the HCA that gives this a 1.3 but gives the following rating:

ex, ex, vg, vg

Many other AGS0 stones I''ve seen register

ex, ex, ex, vg

Is the vg for scintillation due to the crown and pav angle combinations, and does this really matter in view of everything else we know about the stone?

So many questions...

Tunis

Tunis, if you change the pavilion angle to 40.9 instead of 41, scintillation then gets an Ex. I wouldn''t worry too much, the HCA can''t see the diamond and it is only predicting how a diamond might perform in various areas. Other technologies such as brilliancescope could be better for analysing things like scintillation rather than HCA. That is a very well cut stone you have there, so I think you are fine!