Need advice on H&A - Specs inside

[ksomerville]

I''m trying to follow this conversation too and it put worry in my mind about my own diamond as well. Here are the stats according to the AGS and Sarin. Am I okay because "y > x by more than .1 to .2" is not true for this diamond?

AGS
Depth: 61
Table: 55
Crown Angle: 34.7
Pavilion Angle: 40.7

Sarin
Depth: 61
Table: 55.7
Crown Angle: 34.8
Pavilion Angle: 40.8

 

[belle]

Date: 8/11/2005 7:05:25 PM
Author: strmrdr

Date: 8/11/2005 6:32:29 PM
Author: belle
rhino and strm,

i applaud

your efforts in trying to explain this and find it interesting, as i like playing with these programs too…BUT i have to say that i don’t think you can use a 2-d caricature (haven't seen a diamond look like that!

) to split hairs and determine differences in the performance of a diamond you've never even seen. the hca score already designates it as a winner (better than 95% of all diamonds on the market) but more importantly, the idealscope image looks great

besides there is the possibility that the diamond in this thread could be a 34.7 crown angle and 40.8 pavilion angle…who knows if the sarin is right?

sorry boys, i am just one of those kinda girls who doesn’t think the fake ones are as good as the real thing.

Belle,
Both Jon and myself have seen this with our own eyes in similar diamonds.
People split hairs all the time with the hca and ideal-scope images neither of which directly address indirect light performance.
The hca can give you a clue to look into it further but doesn’t provide the whole answer.
Just like we on PS have been separating for the best direct light performance we can also weed out those that have problems in indirect light.
Its no different than rejecting a diamond that has too much white on the ideal-scope image
I am using the computer generated images to show what im talking about.
If you ever happen to be close to Jon's store sometime Im sure he would be happy to demo it for you using real diamonds.

saying similar is a stretch.

using a simulation *is* different than rejecting an idealscope image that has too much white...
the difference is, with an idealscope image you actually have the diamond and light and are taking a real picture of the diamond itself....there is no program or human calculation errors or fakesy wakesy disco lights to manipulate.

just the real diamond and the real light reflecting back through it (or not)

and you want me to use a computer program to try and *guesstimate* what the diamond might look like (with one 2-d caricature view result none the less) in indirect lighting conditions like office lighting (except that as jon points out, i have to use 'jewelry store light'

to get the effect he is looking for) and try and split hairs even further??

don't hate me strm, you and rhino are famous (hey, you're famous!!) for loving the gadgets but i just think there are too many unknowns about this diamond especially exact measurements (for all we know the sarin could be off) for you to try and judge with computers a thousand miles away.

speaking of a thousand miles away...
if i ever do get to ny, i will definitely stop in and see jon...though after this, he is never going to let me in!

 

[strmrdr]

Date: 8/11/2005 8:29:29 PM
Author: ksomerville
I''m trying to follow this conversation too and it put worry in my mind about my own diamond as well. Here are the stats according to the AGS and Sarin. Am I okay because ''y > x by more than .1 to .2'' is not true for this diamond?


AGS

Depth: 61

Table: 55

Crown Angle: 34.7

Pavilion Angle: 40.7


Sarin

Depth: 61

Table: 55.7

Crown Angle: 34.8

Pavilion Angle: 40.8

No problem there.
sounds like a real nice diamond :}

 

[Demelza]

Date: 8/11/2005 8:29:29 PM
Author: ksomerville
I''m trying to follow this conversation too and it put worry in my mind about my own diamond as well. Here are the stats according to the AGS and Sarin. Am I okay because ''y > x by more than .1 to .2'' is not true for this diamond?


AGS

Depth: 61

Table: 55

Crown Angle: 34.7

Pavilion Angle: 40.7


Sarin

Depth: 61

Table: 55.7

Crown Angle: 34.8

Pavilion Angle: 40.8

How does the diamond look to you? That is the most important question. I''ve been agonizing the past few days about whether to reject a diamond that is gorgeous to my eyes because of a few tenths of a degree. Maybe someone might be able to say in a very specific kind of office lighting situation that one stone doesn''t perform as well as another because the crown angle is 2/10 degree "off", but I just don''t know if those kinds of difference are even worth talking about except for academic purposes. I think we can all find things about our diamonds that could be a little better one way or another, but it''s the overall effect that is most important -- on a day to day basis, does your diamond perform well enough in most situations to make you happy? At least that''s how I''m trying to think about it -- all this minutia could make one a little batty!

 

[LadyluvsLuxury]

Date: 8/10/2005 5:14:35 PM
Author: belle

Date: 8/10/2005 4:44:09 PM
Author: LadyluvsLuxury
WOW strmrdr, thanks for linking that. Gives me something ELSE to look for! So is the only way to know if a stone would be lacking in performance in the mentioned lighting conditions through an ISee2?

no, that would be using a machine to split hairs in minute diamond charataristics that your eye probably won''t be able to perceive anyway.

So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?

 

[belle]

Date: 8/11/2005 9:11:28 PM
Author: LadyluvsLuxury

Date: 8/10/2005 5:14:35 PM
Author: belle

Date: 8/10/2005 4:44:09 PM
Author: LadyluvsLuxury
WOW strmrdr, thanks for linking that. Gives me something ELSE to look for! So is the only way to know if a stone would be lacking in performance in the mentioned lighting conditions through an ISee2?

no, that would be using a machine to split hairs in minute diamond charataristics that your eye probably won''t be able to perceive anyway.

So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?

and we have a winner!

yes lll, you are correct.

 

[Demelza]

Date: 8/11/2005 9:15:28 PM
Author: belle

Date: 8/11/2005 9:11:28 PM

Author: LadyluvsLuxury

Date: 8/10/2005 5:14:35 PM

Author: belle

Date: 8/10/2005 4:44:09 PM

Author: LadyluvsLuxury

WOW strmrdr, thanks for linking that. Gives me something ELSE to look for! So is the only way to know if a stone would be lacking in performance in the mentioned lighting conditions through an ISee2?

no, that would be using a machine to split hairs in minute diamond charataristics that your eye probably won't be able to perceive anyway.

So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?

and we have a winner!

yes lll, you are correct.

Belle -- thank you for sparing a lot of us more neurotic types from a lot of unnecessary anxiety!!!

 

[LadyluvsLuxury]

Thanks everyone...and I will forge ahead with another piece of knowledge!

 

[strmrdr]

Date: 8/11/2005 9:15:28 PM
Author: belle

Date: 8/11/2005 9:11:28 PM

Author: LadyluvsLuxury

Date: 8/10/2005 5:14:35 PM

Author: belle

Date: 8/10/2005 4:44:09 PM

Author: LadyluvsLuxury

WOW strmrdr, thanks for linking that. Gives me something ELSE to look for! So is the only way to know if a stone would be lacking in performance in the mentioned lighting conditions through an ISee2?

no, that would be using a machine to split hairs in minute diamond charataristics that your eye probably won''t be able to perceive anyway.

So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?

and we have a winner!

yes lll, you are correct.

With a few exeptions I agree.
shallow/shallow and steep/shallow combos are the exceptions.
Consider this most people spend far more time in indirect light than direct light.

 

[belle]

Date: 8/11/2005 9:21:01 PM
Author: Demelza

Belle -- thank you for sparing a lot of us more neurotic types from a lot of unnecessary anxiety!!!

hehehe...you''re welcome

and thank you for sharing your firsthand view of the diamond performance minutia dilemma solved...a winners a winners a winner!

 

[Rhino]

Date: 8/11/2005 9:11:28 PM
Author: LadyluvsLuxury

Date: 8/10/2005 5:14:35 PM
Author: belle

Date: 8/10/2005 4:44:09 PM
Author: LadyluvsLuxury
WOW strmrdr, thanks for linking that. Gives me something ELSE to look for! So is the only way to know if a stone would be lacking in performance in the mentioned lighting conditions through an ISee2?

no, that would be using a machine to split hairs in minute diamond charataristics that your eye probably won''t be able to perceive anyway.

So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?

Here''s the problem.

People here on this forum have been weened on a strict diet of HCA scores and ideal scope images. I am perhaps one of the strongest advocates of reflector technology besides Garry and will defend it tooth and nail, but it is vitally important to understand the weakness of reflector technologies, just as it is equally important to know about the weakness'' of *any* software, hardware or technology one is consulting when compiling data in a purchasing decision.

In answer to your question "So, as long as you are under HCA 2 then the differences are minute if at all visible to the eye?" the answer is a resounding NO. I''ve been saying this for a while now and finally both GIA and AGS systems concur what I''ve been saying all along about this very subject.

IdealScope images and HCA scores are INACCURATE for determing shallow combinations. In extreme examples you can see the effects of a stone that is too shallow but that is already beyond the point of no return. IS and HCA are *exceptional* for weeding out steep/deep combinations but that is only one part of the equation. I''ve had stones here with HCA scores ranging from .2 to 1.0 that I''d never purchase nor would recommend.

I do not mean any disrespect to Garry. He and I are mates and I think the world of him. What I am saying about the HCA should not be taken personally by anyone but these are my honest, straight from the hip observations and I am not alone in my professional opinion on these issues.

Belle... you are right when you say the stone *could* have pavilion angles of 40.8. However we can''t tell that without a physical facet analysis coupled with a complete optical analysis. We do catch the labs in mistakes from time to time (as in the example posted on this thread with the .815ct) so I really would not know about this particular stone unless I examined it personally of course.

Overall... as strm has pointed out it does appear that it will blow away most stones on the market and if it takes a hit in any metric it will be that of brightness as observed in indirect lighting and that ... not a HUGE difference as pointed out there are much worse. You''re talking to someone very anal here too so keep that in mind. Of stones that would get the GIA "very good" classification this would be one of the best of them.

 

[jin866]

I am trying to learning something here. So exactly what is shallow/shallow and deep/shallow combo?
If crown angle is 34.x and pavillion angle is 40.y, should y>x or x>y? I am a little confused by reading previous messages.
A diamond I am very interested in has the following data:
D: 60.6%
Crown: 34.9
pavil: 40.7
table: 56.2%

Is it deep/shallow combination? Will it have the same issue?

Thanks very much

 

[ksomerville]

Thanks strmrdr. You put my mind at ease. I haven''t been able to see the diamond yet. My boyfriend let me pick out the diamond but I don''t actually get to see it in person until he proposes. Hope he hurries up so I can see for myself.

 

[strmrdr]

Date: 8/12/2005 12:11:43 AM
Author: nana
I am trying to learning something here. So exactly what is shallow/shallow and deep/shallow combo?

If crown angle is 34.x and pavillion angle is 40.y, should y>x or x>y? I am a little confused by reading previous messages.

A diamond I am very interested in has the following data:

D: 60.6%

Crown: 34.9

pavil: 40.7

table: 56.2%


Is it deep/shallow combination? Will it have the same issue?


Thanks very much

34.x 40.y with x>y might be bad

34.9 and 40.7 isnt bad.
It would be splitting hairs to fine to say its a problem.
That combo is a deep/med not a deep/shallow
There is a sharp drop off between 40.6 and 40.7 with a 34.9 crown.
There is a slight difference between 40.7 and 40.8 and 40.9 but not enough to worry about.

It scores a 1 on the hca and not many problem stones will.

40.6 would score a .7 which to me indicates check it to see if its a problem combo and it would be. 40.7 is fine :}

I may refine that too:

34.x 40.y with x>y AND hca <= 1 might be bad

 

[JohnQuixote]

Date: 8/11/2005 9:37:05 PM
Author: Rhino

Here's the problem.

There is a much bigger problem, actually.

I’ve been watching and waiting to put the brakes on this until I heard back from the original poster. Guys, the original diamond in this thread doesn’t meet the listed proportions. I could tell that from looking at its ideal-scope, which looks a lot like a WF image…yet we did not provide it.

Upon further investigation:

1.The OP got the ideal-scope from an ebay seller along with the proportions. We believe it to be one of our images

If true it’s a big issue. This kind of thing has happened to us and other PS vendors before. We’re investigating, and apologies in advance if someone else is using color-corrected lighting at 5300 kelvin and this is a coink-ee-dink.

2. So… I did some analysis and… Bzzt! The given proportions don’t match the image. Also… Bzzt! The given proportions set doesn’t even agree with ITSELF!? Either the depth or table is incorrect (more to come).

Ding-ding-ding-ding!...Belle, you win the award for figuring it out first.

Belle's DiamCalc on page 1 showed the proportions don’t work. She even said that! But by then the thread's focus was on simulations and software and Isee (oh my!) and no one checked the MOST important numbers on the subject diamond – the ones that are missing.

All-together now... "We must remember basics." The numbers given are ok for HCA, but you must have diameter spread and depth in mm for any detailed assessment. It would tell actual depth and out of round and give a solid outline. Rhino pointed out that we have been weaned on HCA. Maybe that is why no one asked about mm. So I’d ask you guys to think about this: The HCA has been criticized in this thread and yet NO predictions anyone made about that subject diamond can possibly be any better than HCA can do - because those were the only numbers provided.

So where is the answer about those ill-proportions? ...In the actual image, of course

(ta-da!)

Like Belle noted, the proportions do not work, though they are close. If the image was lifted it was apparently to represent a diamond that was NEAR these numbers… So we used Garry’s framing technique (I hope David is reading).

56, 60.2, 34.9, 40.6 Thin-Med does not compute. The wire-frame shows the angles are ok but either the table or the depth is wrong. So let’s keep 60.2D but increase table to 57.4 (thin g). No, the wire frame does not fit snugly enough especially under the table.

 

[JohnQuixote]

However, if we keep the table the same and increase depth to 61.3 (med g)… viola!

These proportions, while more representative of the ideal-scope image, still cannot be relied on. The actual imagery should have been the emphasis in the first place.

Post edited: From replies that follow I must have given the impression that these are actually this image's numbers. No way. I was just showing how a wire-frame fit can result in leeway (see the one on the next page with completely different angles that also fits). We do not carry 34.9/40.6 in ACA and if one had ever been in Expert Selection - there are none now and I can't recall one - it would have been a rare example, 'expertly selected' by Brian's eyes, and priced to be a good value.

 

[JohnQuixote]

You know, the points made in this thread about sarin potentially being off and lighting metrics in simulations being fallible are undenaible. Scans and sims are useful but a diamond just isn’t a .jpg you can email to someone that replicates itself identically for assessment.

I urge consumers in this thread (especially the worried ones) to use the faux pas as an educational experience – both in the very interesting points Strm and Rhino made about the mutually observed diamond – and as a cautionary tale for reliance on numbers.

As an educator I appreciate the teaching diamond on Rhino’s website, but I just don’t believe that it can be the final word on a completely different diamond with unkowns. Now, if all angles, percentages, minor facets, girdle, culet and (for splitting hairs) weight + spread and depth in mm were the same I could buy it. But in this case we only had HCA numbers to go by for the diamond that people were judging (wrong numbers too).

Another thing while we’re at it. Should we make acute comparisons between diamonds that are 40% different in size without them in hand (1.28 and .815)? Overall performance assessment ok, but I don’t know about fractional decisions with different sizes, especially not knowing very much about one of them. Even AGS is going to provide different stages for evaluation of different sizes in the ASET.

Here are some examples of size/performance difs: Brian’s eyes have told him for a long time that melee goods can have slightly steeper angles and still perform well, though not every sim agrees with that. It makes sense. The mirrors are much smaller and closer together in the same way a rotating disco ball with 1 inch mirrors is livelier than a bigger ball with 1 foot mirrors. These dynamics are also the reason cuts like the Solasfera with more facets are considered more appealing in bigger sizes. Even if you think the 40% size difference is not a factor, we couldn’t know if the control and the test subject were similar enough because we really didn’t know diddly about the test subject here.

Anyhow, back to the computers and numbers… "With great computing power comes great responsibility." PREDICTION is the key word. Yes to broad assessment. Yes to acceptance or rejection, but NO to a laptop-generated answer as to what someone will find better or worse when splitting hairs.

Don’t get me wrong - I use DiamCalc each day. Brian absolutely uses it. His entire presentation for the IDCC and his ACA research were/are done using it. It is cool that we have 3D scans and computer simulations, but Brian’s eyes have told him things about fine tuning and small and large and in-between for many years that are just not picked up in simulations. To this end I think scans and sims are a nice reference for trade experts who have actual diamonds in hand as a means of correlation and ‘reality check,’ but perhaps we need to be sure enthusiasm doesn’t carry us too far. It can become a matter of believing what you want to see, rather than seeing what’s really there.

 

[Regular Guy]

Let''s not let the proximity of life''s imitating art interrupt a good brawl.

After all, Einstein didn''t let a dose of reality interrupt a good theory, so why should we.

Rhino, with Storm as a supportive presence, is purporting you might need to triangulate your info to get a more complete picture, with respect to the look of a diamond in diffuse (and, as Storm adds, more commonly experienced) lighting.

Although there may be agreement about the ideal procedures of getting your diamond in question to either or both an expert, or to the lighting environment in question...with respect to other reportable data points....the sufficiency of HCA and idealscope (and never mind the H&A just now) seem to be what''s in question for making a judgement.

Or am I not reading this correctly?

 

[strmrdr]

All that dont change the fact that a 34.9, 40.6 combo has all the problems that myself and Jon said they do.

 

[strmrdr]

Date: 8/12/2005 4:00:57 AM
Author: JohnQuixote

Don’t get me wrong - I use DiamCalc each day. Brian absolutely uses it. His entire presentation for the IDCC and his ACA research were/are done using it. It is cool that we have 3D scans and computer simulations, but Brian’s eyes have told him things about fine tuning and small and large and in-between for many years that are just not picked up in simulations. To this end I think scans and sims are a nice reference for trade experts who have actual diamonds in hand as a means of correlation and ‘reality check,’ but perhaps we need to be sure enthusiasm doesn’t carry us too far. It can become a matter of believing what you want to see, rather than seeing what’s really there.

For the 20th time or so in this thread.
Both Jon and myself have observed this in different diamonds and are using diamcalc to explain it. It happens live with it :}

After Jon posted that learning stone I set out to see if I could find such combo''s myself and managed to.
It exists and is a problem.
Yes in all likelyhood a small one but if one is going to go nuts getting a diamond with that last bit of extra direct light performance using the hca and IS images and what not, doesnt it make sence to take a few minutes to consider the indirect light performance also?

 

[strmrdr]

Good work on catching the stolen IS image belle :}

 

[strmrdr]

You will find that hardly any people that bought diamonds from the pricescope top vendors have diamonds that this is a problem with.
Could it be that they were filtering them out all along?
Things that make you go hmmmmmmmm :}

There have been a few poping up after Garry''s experments with his wife''s ear rings for pendants and ear rings but before that not very many of them.
More things that make you go hmmmmmmmmmmm :}

 

[Regular Guy]

My curiosity about best and intended implementation of the HCA, given the additional practical constraints of shopping procedures, have preceded me here. (edited to add...And regarding shopping procedures, although there's a lot of valuable discussion here on the variations implied by different lighting environments, the practical implication of the typical Pricescoper's shopping environment, where only one to several diamonds are actually looked at, seem to me to have a greater relative impact and concern to the typical prosumer on this board).

Though there's more to this discussion (including the expected broad based relevancy of the IS), the low HCA scores again seem to be in question.

You can sort the options on the search by cut database. If you sort order from lowest to highest, you'd see options below 1 number anywhere from 11 - 14% of those described, depending on whether or not you screen out performers outside of excellent (clearly not intended to be judged as equal to those counted as excellent).

Sorting out the variations in opinion could be helpful to me, as they vary, or maybe it's just my lack of understanding.

A low HCA score should, under the basically linear(earistic) model presented by HCA, should allow a more "trustworthy" score and predictability of result, less effected by variation in measurement. This makes sense to me, at least.

Also, mentioned by Garry is the greater likelihood that the symmetry will make less of a difference in this instance, given the greater "lack of outliers" that will provide this score (this could certainly be understood and expressed better). Not intending to pull Wink in here unnecessarily, but in sorting these both before and now, I see many of his options with the low scores, as though he has cherry picked them this way; maybe he has a useful comment? Also, however, I'm not sure that Johns' comment in a recent thread suggest he's in agreement with this theory about the relative effect of the minors, in principle.

Less understood by me, but posited here, is the relationship between shallowness and having a low score. Garry has previously tried to impute the meaning here, I think. Will a lower score tend to make a shallower presentation?

Possible outcome, with consideration of wanting to avoid consequences of measurement variation...look mostly for HCA of 1 - 1.5?

Sorry, I'm more in the business of asking questions here than giving answers.

Regards,

 

[belle]

Date: 8/12/2005 2:47:30 AM
Author: JohnQuixote

Ding-ding-ding-ding!...Belle, you win the award for figuring it out first.

wow! this is sooo cool! i never win anything!

oh wait....what did i win?

 

[belle]

Date: 8/12/2005 9:47:52 AM
Author: strmrdr
Good work on catching the stolen IS image belle :}

uhhhhh...i didn't know it was stolen

but i'll take credit for trying to play your picture game and figuring out that the proportions didn't match up even though i thought that could have been my mistake only to find out now that it wasn't!

eta: speaking of the stolen image... is anyone else here alarmed at the fact that this is potentially a stolen image????

 

[Maxine]

If scores below 1 are not desirable, why isn''t that info included w/the HCA?????
Why say any score under two, if the intention is only to use scores between .9 and 1.5 or 1 and 1.5??????

 

[strmrdr]

Date: 8/12/2005 11:45:53 AM
Author: Maxine
If scores below 1 are not desirable, why isn''t that info included w/the HCA?????

Why say any score under two, if the intention is only to use scores between .9 and 1.5 or 1 and 1.5??????

thats where it gets complicated not all diamonds that score say .6 will be a problem just the shallow/shallow ones and the deep/shallow ones.

 

[Regular Guy]

Date: 8/12/2005 11:45:53 AM
Author: Maxine
If scores below 1 are not desirable, why isn''t that info included w/the HCA?????
Why say any score under two, if the intention is only to use scores between .9 and 1.5 or 1 and 1.5??????

Maxine,

In fairness, Garry isn''t saying this, Jonathan and Storm are.

 

[Maxine]

Date: 8/12/2005 11:52:01 AM
Author: strmrdr

Date: 8/12/2005 11:45:53 AM
Author: Maxine
If scores below 1 are not desirable, why isn''t that info included w/the HCA?????

Why say any score under two, if the intention is only to use scores between .9 and 1.5 or 1 and 1.5??????

thats where it gets complicated not all diamonds that score say .6 will be a problem just the shallow/shallow ones and the deep/shallow ones.

so, what ones are OK???? The ones that fall into the default parameters given on the HCA??? Any others???

 

[strmrdr]

Date: 8/12/2005 11:52:37 AM
Author: Regular Guy

Date: 8/12/2005 11:45:53 AM

Author: Maxine

If scores below 1 are not desirable, why isn't that info included w/the HCA?????

Why say any score under two, if the intention is only to use scores between .9 and 1.5 or 1 and 1.5??????

Maxine,


In fairness, Garry isn't saying this, Jonathan and Storm are.

Garry has said it in the past.
One of the reasons it doesnt get talked about much is to avoid confusion.
For the most part the vendors didnt used to carry those combos so it wasnt an issue.

edit> off to work .. more later... Your turn Belle :}