40.4 degree pavilion angles & below...

[Regular Guy]

So, presumably it is well known, what Paul said, here:

"In the pavilion, somewhere around 40.5° or lower, the light performance goes down sharply...."

and this was picked up in this more recent thread, here, where Hedarud is shopping for a diamond.

Also, in this other contemporary thread, there''s some discussion about the extent to which 41 degrees is some kind of threshold. Likewise, help me understand the extent to which, when we go under 40.5 degrees, without too much reference to the crown angle, we have problems....

Thanks!

 

[ML2014]

First, thank you for putting this question out there! I purchased a diamond that has a 40.4 PA (and a VG cut reating from GIA). I have been struggling about wheter or not to keep it. While I''ve gotten nothing but support (to keep it) from PSrs based on my posts, when I see others asking questions about diamonds with a 40.4 PA (or less), I get the feeling that most folks think that stones that have a 40.4 degree PA or a VG cut rating from GIA are not excellent stones.

I compared my stone which is a VG cut to other GIA Excellent cuts (don''t know what there actual angle #''s were, ec.), but my stone blew them away. There was just something special about it. Now that I have it and can look at it more cosely,I do see that there is less scintillation/fire right under the table, not sure if that is a result of the lower PA, but again, when I compared it to the EX cut stones, my stone had something else that set it apart (not sure what it is). But I spent alot of money on it and I am wondering if I should have compared it to more stones.

Here are my stats: PA 40.4, CA 34.5 , T is 57% , lgf% is 85% star% is 55% and it is 1.51 ct, (7.32-7.36 x 4.49). I think strm told me in a separate post that the larger lgf may be minimiizing any issues I would have with the lower PA.

Outside in sunlight, my stone is extremely bright (blindingly at times). It doesn''t perform well in every lighting setting but when it does, it can be amazing. My problem is that I don''t know if I would see an appreciable difference if the PA was a bit higher (which I think would have gotten it a GIA excellent).

I was planning on going to my jewler this week just for a sanity check and compare it to a few more stones. What would help me though is getting a better understanding if my stone is off that cliff so to speak, and if I would see an appreciable difference with a higher PA (or different PA/CA combination).

Thanks again for getting this out there- I hope others chime in.

 

[Ellen]

Date: 7/17/2007 10:17:43 AM
Author: Kajamie
I was planning on going to my jewler this week just for a sanity check and compare it to a few more stones. What would help me though is getting a better understanding if my stone is off that cliff so to speak, and if I would see an appreciable difference with a higher PA (or different PA/CA combination).

Thanks again for getting this out there- I hope others chime in.

Not a bad idea, as you want to love your ring and be content with it. I would ask your jeweler to show you some stones (AGS0, and GIA EX if he has some) with crown and pavillion angles in the 34-35/40.7-41 range. Then compare, preferably away from the jewelry lights.

 

[ML2014]

Date: 7/17/2007 10:25:58 AM
Author: Ellen

Date: 7/17/2007 10:17:43 AM
Author: Kajamie
I was planning on going to my jewler this week just for a sanity check and compare it to a few more stones. What would help me though is getting a better understanding if my stone is off that cliff so to speak, and if I would see an appreciable difference with a higher PA (or different PA/CA combination).

Thanks again for getting this out there- I hope others chime in.

Not a bad idea, as you want to love your ring and be content with it. I would ask your jeweler to show you some stones (AGS0, and GIA EX if he has some) with crown and pavillion angles in the 34-35/40.7-41 range. Then compare, preferably away from the jewelry lights.

You are right Ellen, and I''lll call her in advance and give her the specs you noted (thank you!). My feeling is that I need a balance between the paper and what I see in the stone. I am a believer that just because it is great by the numbers, it might not be appealing to the (my) eye. I just don''t know what I should be looking for. And I feel badly saying that because I should trust my judgement.

Years ago, I would have only considered E-F VS1 diamonds. When I sat with my jewler, she was the first person who explained the importance of cut. I found Pricescope at the same time I was looking at diamonds with her and just about everything I read supported what she and I discussed. The one thing that was different relative to the cut had to do specifially with this stone. I knew (based on what she and I discussed and what I read here) that I should really have looked only at Excellent rated cut stones, but I kept going back to this one. It actually cost more than the Ex cut stones I was considering (because it was larger) and since there was just something about it, I went with it. So, why am I second guessing myself? I guess it is because I spent alot of money on it and I want to make sure I have a top performing stone. In buying a VG cut stone, I wasn''t looking for a bargain, and cut wasn''t something I wanted to compromise on.

My diamond is an H SI1, and I''ve come a long way from my initial comfort zone in that regard (its eyeclean, well, there is a feather that I think I can see, but as far as I am concerened since I can''t tell for sure, its eye clean enough for me). I owe that shift in thought to Pricescope. It really opened up a new world of diamonds for me to consider. I can''t help but feel that I''ve compromised on cut though. I am basing that on the numbers, and not knowing for sure what a knock out stone should look like. My lesson here is that I should have had it appraised before I had it set, maybe that would have given me the assurance I needed that I bought a fantastic diamond. I think by looking at some more stones, just to compare, I''ll know if indeed I have a diamond that I think is fantastic.

BTW, all of my overanalyzing has had some very positive results. I know that for me, an H colored diamond can be white, white, white and that an SI1 diamond for a ring can be a great find as long as it is eyeclean. I also learned that I really prefer the longer lgf, and I also prefer a stone that strikes a balance between being white/brilliant and colorful/fiery.

Sorry for the long post!

 

[Ellen]

Date: 7/17/2007 11:31:15 AM
Author: Kajamie


Years ago, I would have only considered E-F VS1 diamonds. When I sat with my jewler, she was the first person who explained the importance of cut. I found Pricescope at the same time I was looking at diamonds with her and just about everything I read supported what she and I discussed. The one thing that was different relative to the cut had to do specifially with this stone. I knew (based on what she and I discussed and what I read here) that I should really have looked only at Excellent rated cut stones, but I kept going back to this one. It actually cost more than the Ex cut stones I was considering (because it was larger) and since there was just something about it, I went with it. So, why am I second guessing myself? I guess it is because I spent alot of money on it and I want to make sure I have a top performing stone. In buying a VG cut stone, I wasn''t looking for a bargain, and cut wasn''t something I wanted to compromise on.

Well, that counts for a lot.

In the end, after you have looked at a good variety, it really is numbers be damned, and you go with what your eyes love, not the piece of paper!

I''m not sure how many stones you compared yours to, but you may already have your answer. However, it won''t hurt to look one more time, to be sure. You''re right, it IS a lot of money, and everyone wants to be comfortable with such an expenditure. Please let us know what you decide!

 

[elmo]

I agree with Ellen. Not to sound like a cut nitpicker but I'd make the choice as obvious as possible, and move as far away from what you have there by asking for shortish lower girdle facets, a smallish table, and fairly tall crown, while staying within a "Tolkowsky ideal" range. Shouldn't be that difficult to find, especially if it's not something you plan to keep...you can search for something specific later if you prefer that look. Stick with stones with AGS reports so that the numbers nitpicking means something

.

 

[strmrdr]

Hey RG you have learned enough too know its totally silly to define a diamond by one number it cant be done.

 

[ML2014]

Thanks Ellen and Elmo, I know what I need to do to get MY answer (look at more stones).

Regular Guy, my apologies, I know you weren''t looking to make this thread about one stone. Just wanted to share my real life example of a stone with a 40.4 PA. I hope you get your answers as well.

 

[belle]

Date: 7/17/2007 12:50:31 PM
Author: strmrdr
Hey RG you have learned enough too know its totally silly to define a diamond by one number it cant be done.

D I T T O (with some minor spelling and grammatical changes)

 

[strmrdr]

Date: 7/17/2007 10:17:43 AM
Author: Kajamie
First, thank you for putting this question out there! I purchased a diamond that has a 40.4 PA (and a VG cut reating from GIA). I have been struggling about wheter or not to keep it. While I''ve gotten nothing but support (to keep it) from PSrs based on my posts, when I see others asking questions about diamonds with a 40.4 PA (or less), I get the feeling that most folks think that stones that have a 40.4 degree PA or a VG cut rating from GIA are not excellent stones.

I compared my stone which is a VG cut to other GIA Excellent cuts (don''t know what there actual angle #''s were, ec.), but my stone blew them away. There was just something special about it. Now that I have it and can look at it more cosely,I do see that there is less scintillation/fire right under the table, not sure if that is a result of the lower PA, but again, when I compared it to the EX cut stones, my stone had something else that set it apart (not sure what it is). But I spent alot of money on it and I am wondering if I should have compared it to more stones.

Here are my stats: PA 40.4, CA 34.5 , T is 57% , lgf% is 85% star% is 55% and it is 1.51 ct, (7.32-7.36 x 4.49). I think strm told me in a separate post that the larger lgf may be minimiizing any issues I would have with the lower PA.

Outside in sunlight, my stone is extremely bright (blindingly at times). It doesn''t perform well in every lighting setting but when it does, it can be amazing. My problem is that I don''t know if I would see an appreciable difference if the PA was a bit higher (which I think would have gotten it a GIA excellent).

I was planning on going to my jewler this week just for a sanity check and compare it to a few more stones. What would help me though is getting a better understanding if my stone is off that cliff so to speak, and if I would see an appreciable difference with a higher PA (or different PA/CA combination).

Thanks again for getting this out there- I hope others chime in.

I remember that stone being discussed.
The cutter knew what he was doing when he put the longer lgf on it.
When comparing it other stones do so on hand at both full and half arm lenth.

 

[ML2014]

Date: 7/17/2007 1:19:23 PM
Author: strmrdr

Date: 7/17/2007 10:17:43 AM
Author: Kajamie
First, thank you for putting this question out there! I purchased a diamond that has a 40.4 PA (and a VG cut reating from GIA). I have been struggling about wheter or not to keep it. While I''ve gotten nothing but support (to keep it) from PSrs based on my posts, when I see others asking questions about diamonds with a 40.4 PA (or less), I get the feeling that most folks think that stones that have a 40.4 degree PA or a VG cut rating from GIA are not excellent stones.

I compared my stone which is a VG cut to other GIA Excellent cuts (don''t know what there actual angle #''s were, ec.), but my stone blew them away. There was just something special about it. Now that I have it and can look at it more cosely,I do see that there is less scintillation/fire right under the table, not sure if that is a result of the lower PA, but again, when I compared it to the EX cut stones, my stone had something else that set it apart (not sure what it is). But I spent alot of money on it and I am wondering if I should have compared it to more stones.

Here are my stats: PA 40.4, CA 34.5 , T is 57% , lgf% is 85% star% is 55% and it is 1.51 ct, (7.32-7.36 x 4.49). I think strm told me in a separate post that the larger lgf may be minimiizing any issues I would have with the lower PA.

Outside in sunlight, my stone is extremely bright (blindingly at times). It doesn''t perform well in every lighting setting but when it does, it can be amazing. My problem is that I don''t know if I would see an appreciable difference if the PA was a bit higher (which I think would have gotten it a GIA excellent).

I was planning on going to my jewler this week just for a sanity check and compare it to a few more stones. What would help me though is getting a better understanding if my stone is off that cliff so to speak, and if I would see an appreciable difference with a higher PA (or different PA/CA combination).

Thanks again for getting this out there- I hope others chime in.

I remember that stone being discussed.
The cutter knew what he was doing when he put the longer lgf on it.
When comparing it other stones do so on hand at both full and half arm lenth.

I don''t think I did compare at full and half arm lenghth before I bought it. I think it was pretty much just at arms lenghth so I''ll be sure to do this. What is it that I would be looking for - what will jump out at me to know that yes, I could have done much better? Or, is that just going to be obvious? (or conversely, my feeling right now is if I see no diff, then what does it matter anyway).

 

[whatmeworry]

Ira,
feel free to chime in with your own personal observations. You have in your possession 40.4 and below?

 

[Bubbles2go]

I''ve been watching these forums while searching for a diamond and all the talk about PAs around 41 has me curious. I''ve come across GIA excellent stones with a 40.6/36.5 combination (62.4 depth, 56 table, 80 LGF, 50 star if I remember right). I didn''t see the stone in person and don''t have access to the ideal scope images. Any thoughts on what a stone like that would look like?

 

[Regular Guy]

Date: 7/17/2007 2:07:26 PM
Author: whatmeworry
Ira,
feel free to chime in with your own personal observations. You have in your possession 40.4 and below?

WMW...yes, I do; thanks.

So this thread is prompted by Hedarud's query...where what seemed like one could make a simple "accept provisionally" based on the affirmative HCA score, turned into a thumbs down from at least a couple of the savvy readers.

Really, personally, it is more a continuation of my query here...on the use, and interpretation of DiamandCalc. Reviewing it again, I am reminded that the leakage reviewed with the IS is only part of the evaluation story...yet Garry emphasizes it regularly, and this board has largely adopted it.

Everything is only relatively good, somewhat. This is contrast...right? It is challenging to compare, when there's little to compare to. My wife & I are happy with our purchase...but without a more extensive set of comparisons...it's hard to say what we didn't get, and how it would compare.

Since the recent thread suggested the pavilion angle of 41 represented a sort of line in the sand...and again...Hedarud's problem seemed associated with his lower pavilion angle, I was reminded of the other side, where a line in the sand has been conjectured about (see Paul's real quote above), and wondered if anyone, as Brian has done in the 41 thread, would posit some suppositions about low pavilion angles, and comment on them...or invite them to.

It did occur to me that this might be about the rareness with which FIC's occur, inasmuch as more ideally scored diamonds with these low pavilion angles might tend to be FIC, FICs are rare...and maybe there's not much practical basis for comment, because they're not seen a bunch. But, then I played with HCA a bit...and I don't know that the crown angle being over 35.5 is a critical factor...but I'm not sure.

Also...I wonder if the frame or window in which the HCA angles are displayed got truncated. Seems like the "boxed" areas used to look smaller, in comparison to the "accepted big red area," but I'm not really seeing this so much as I interpret it today (though this is clearly a somewhat big area...in comparison to the contrasted charts/boxed represented by AGS & GIA...).

And, another question. Looking at the presentation of Hedarud's option...the background seems more yellow in the HCA map, whereas mine, with 40.1 pavilion, and 35.8 crown (also table 55 & depth 62), the background is more red. I doubt these represent non-substantive artifacts as HCA presents...but don't know.

Just questions. I have been talking out loud. Many thanks for reviewing.

 

[strmrdr]

Date: 7/17/2007 2:20:40 PM
Author: Bubbles2go
I''ve been watching these forums while searching for a diamond and all the talk about PAs around 41 has me curious. I''ve come across GIA excellent stones with a 40.6/36.5 combination (62.4 depth, 56 table, 80 LGF, 50 star if I remember right). I didn''t see the stone in person and don''t have access to the ideal scope images. Any thoughts on what a stone like that would look like?

A combo like that would tend to be very fiery, if it has decent optical symmetry could be a very nice stone.
40.6 balances with a 36.5 well and the 80% lgf is where it needs to be for the combo.

 

[Ellen]

Date: 7/17/2007 2:20:40 PM
Author: Bubbles2go
I''ve been watching these forums while searching for a diamond and all the talk about PAs around 41 has me curious. I''ve come across GIA excellent stones with a 40.6/36.5 combination (62.4 depth, 56 table, 80 LGF, 50 star if I remember right). I didn''t see the stone in person and don''t have access to the ideal scope images. Any thoughts on what a stone like that would look like?

Hi Bubbles,

It would be best if you started a new thread with your questions, you''ll get more responses that way.

 

[strmrdr]

Date: 7/17/2007 1:47:38 PM
Author: Kajamie

I don''t think I did compare at full and half arm lenghth before I bought it. I think it was pretty much just at arms lenghth so I''ll be sure to do this. What is it that I would be looking for - what will jump out at me to know that yes, I could have done much better? Or, is that just going to be obvious? (or conversely, my feeling right now is if I see no diff, then what does it matter anyway).

You will know if you see it and I suspect you wont to any great degree.

 

[whatmeworry]

Date: 7/17/2007 2:57:13 PM
Author: Regular Guy

Date: 7/17/2007 2:07:26 PM
Author: whatmeworry
Ira,
feel free to chime in with your own personal observations. You have in your possession 40.4 and below?

Everything is only relatively good, somewhat. This is contrast...right? It is challenging to compare, when there''s little to compare to. My wife & I are happy with our purchase...but without a more extensive set of comparisons...it''s hard to say what we didn''t get, and how it would compare.

I think it''s just as important to say what you did get. You got something that you and the Mrs. are happy with. Just as Kajamie has a pretty stone to her eyes as well. So apparently with the right other combinations, you can get a nice looking diamond with 40.4 or below.

My mother in law has a pair of earrings. When put to the ideal scope test, they would make you run for the door in a hurry. Lots of leakage. Deeply cut. Yet when examining them with my eyes. They''re nice. They''re not comparable to super duper loopers, but still nice.

 

[ML2014]

Date: 7/17/2007 3:12:58 PM
Author: strmrdr

Date: 7/17/2007 1:47:38 PM
Author: Kajamie

I don''t think I did compare at full and half arm lenghth before I bought it. I think it was pretty much just at arms lenghth so I''ll be sure to do this. What is it that I would be looking for - what will jump out at me to know that yes, I could have done much better? Or, is that just going to be obvious? (or conversely, my feeling right now is if I see no diff, then what does it matter anyway).

You will know if you see it and I suspect you wont to any great degree.

Just wanted to post an update, as I did get a chance to look at a GIA graded "Excellent Cut" stone with my jeweler. I don''t have the angles available (sorry - I know that would help lend some perspective here), so I can''t say what they were right now, but there was no appreciable difference between my Very Good GIA graded stone (40.4PA AND 34.5 CA). I did notice differences though

- the arrows on the EX cut stone were darker and more apparent through the girdle (mine are almost gray, although a dark gray- I see them they are just not bold). I liked the look offered by my stone better.

- The arrows were thicker too. I actually prefer the thinner arrows so that was a good comparison.

Sparkle factor- equal match in various lighting conditions.

Fire- perhaps a tad more fire in the EX cut stone but mine was sooooo close, it could have been just the way I was tilting the stones (if that makes sense).

The other thing which was really helpful was that in the lighting conditions where my stone didn''t perform as much, neither did the Ex cut.

Overall, my 40.4 (IMHO) kept up with the Ex cut, and the differences were so small, to me at least, that they didn''t justify an increase in price or upgrade to an Ex cut stone. Frankly, there I things I see in my stone that were missing from the Ex cuts, perhaps that is due to the long lgf% (85%) but regardless, I have my answer. I just really like my stone. Yeah!

As an aside, my stone is a 1.51 ct H SI1- the stone I compared it to was a 1.52 F VS2. The color looked the same- I couldn''t believe how white my diamond looked. I am feeling better about it every day.

I guess where I am ending up is that everytime I compare my VG cut to an excellent cut, both stones look awesome, and that''s all that matters, not the numbers. I really agonized over the shallow PA but the true test for me was comparing my stone to another EX cut to compare the differences. So, in spite of the shallow PA and med- thick girdle, while my diamond might not be considered Ex cut by GIA, it is considered awesome by me.

 

[ML2014]

Oh and STRM...I did look at the two diamonds at arms lenghth and at half arms lenghth- no diff. Were you thinking that b/c of the shallow PA my stone might look a little darker when I looked at it up close?

 

[Ellen]

Date: 7/24/2007 7:40:22 PM
Author: Kajamie

Overall, my 40.4 (IMHO) kept up with the Ex cut, and the differences were so small, to me at least, that they didn''t justify an increase in price or upgrade to an Ex cut stone. Frankly, there I things I see in my stone that were missing from the Ex cuts, perhaps that is due to the long lgf% (85%) but regardless, I have my answer. I just really like my stone. Yeah!

As an aside, my stone is a 1.51 ct H SI1- the stone I compared it to was a 1.52 F VS2. The color looked the same- I couldn''t believe how white my diamond looked. I am feeling better about it every day.

I guess where I am ending up is that everytime I compare my VG cut to an excellent cut, both stones look awesome, and that''s all that matters, not the numbers. I really agonized over the shallow PA but the true test for me was comparing my stone to another EX cut to compare the differences. So, in spite of the shallow PA and med- thick girdle, while my diamond might not be considered Ex cut by GIA, it is considered awesome by me.

Yay!

It sounds like you did really well in comparing them. Good for you. And even better, you''re happy with your stone. Conrats!

 

[strmrdr]

I had a long reply writen out but a board error ate it so just gonna sum it up..

Congrates! enjoy your diamond!

 

[ML2014]

Thanks Ellen- you have such a great way of highlighting the sound bytes- it helped me see what I was saying so much better. If I look back at my other posts, I think I''ll see that I am saying the same things over and over- that the numbers don''t jive but I prefer the stone. It is so easy to get caught up in someone else''s idea of ideal and lose your own at the same time. I''m glad that I had an opportunity to sit back and determine what I wanted to see everytime I looked down at the ring.

Thanks for all of your help!

 

[ML2014]

Thanks Strm- while I would have loved to hear what you had to say, I think I get it.

You guys are the best.

 

[Ellen]

Date: 7/24/2007 8:20:01 PM
Author: Kajamie
Thanks Ellen- you have such a great way of highlighting the sound bytes- it helped me see what I was saying so much better. If I look back at my other posts, I think I''ll see that I am saying the same things over and over- that the numbers don''t jive but I prefer the stone. It is so easy to get caught up in someone else''s idea of ideal and lose your own at the same time. I''m glad that I had an opportunity to sit back and determine what I wanted to see everytime I looked down at the ring.

Thanks for all of your help!

I''m glad you did too, I wish we all were so lucky!


Glad we could help!

 

[Garry H (Cut Nut)]

This link is what I wrote on the subject (un edited) 7 years ago http://www.diamond-cut.com.au/03_inverse_relationship.htm

And this link explains the lighting model from the Gilbertsonscope http://www.diamond-cut.com.au/07_gilbertson.htm

I think it shows that there is no point discussing individual pavilion angles nor narrow recomendations for combinations.




Kajamie may I suggest you please go to HCA, click the button and then read the link that contains a warning under the result.

 

[whatmeworry]

Kajamie, Congrats

and thanks for the nice report on your diamond comparison with an GIA EX.