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DiamCalc Request

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Spinning Head

Rough_Rock
Joined
Feb 24, 2003
Messages
10
Hope some can do a diamcalc run on this for me:

0.84ct
6.12-6.15x3.72
Depth % 60.7
Table% 57
Crown Ang. 33.9
Pav Ang. 40.9
Girdle 1.0-1.1%
Culet: Pointed

If more info is needed, please let me know.

S. Head
 

Spinning Head

Rough_Rock
Joined
Feb 24, 2003
Messages
10
Ok maybe what I should have said was, please give me an idea of how it rates.

Color E
VS1

Is the girdle too thin?
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
Hi spinning head,

Overall your proportions look very good. These graphics assume great symmetry (not sure whether you stone has this kind of symmetry or not) but here are 2 examples of many possiblities you have here in way of simulate IdealScope images.

Using the dimensions you listed the graphic to the left illustrates your dimensions with the shorter star/lower girdle combo vs the same dimensions but changing the minors to the longer star/upper girdle combo.

Obviously in your case the example with the longer star/lower girdle combo increases your light return and lessens the leakage. If you have a stone like the image on the right ... THEN you've really got a cherry. The only way to know for sure where your stone falls either/or or anywhere in between is to have a pro check it out. Should be a good looking stone although the minors can affect how this diamond would optically check out.

Hope this helps.

Rhino

spinninghead.jpg
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792
In order to obtain really accurate results on the DiamCalc we need to know what the high and low parameters are for the crown angle and pavilion angle measurements. The measurements you provided are averages based on the actual high and low readings for the eight facets that make up each section. The average crown angle you indicated of 33.9 degrees could be the average of measurements that range from 33.8 to 34.0 degrees (which would be excellent) or something broader like 33.4 - 34.4 degrees, etc. the same holds true for the pavilion angle. Ask whoever provided you with the measurements you posted to provide you with the full version of the crown angle and pavilion angle reports and you will not only know the range that determined the averages, but which facets are high and low and the consistency that the diamond was cut on a facet-by-facet level. Assuming that the diamond was cut on the tighter end of the possibilities, the DiamCalc results for the mathematical ray tracing estimation are as follows:



And the results of the DiamCalc analysis are as follows:



However, we must remind you that these results are merely an estimation... Additional information is required to make the estimation more accurate.
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792

----------------
On 3/1/2003 1:44:22 AM Cut Nut wrote:
Hey Rhino I have noticed that when you are modeling stones you neglect to enter the actual diameter including variances.
R & T you negelected to do this also (I can tell because the score is a little lower when you use the asymetrical diamensions).----------------
And that's because we're minors in the Big League compared to you Big Guy... Better explain what you're referring to so that we all can learn... We just entered the minimum and maximum diameter measurements along with the depth as provided by the client, what are we missing? We don't see an option in DC to enter anything else even within the advanced tabs... Help!
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
you are correct Gary. Thanks for pointing that out. I'll be more careful of that. Another aspect too that is left out is actual variances on a facet by facet basis too which would of coures give an even more accurate rendition of the actual stone. The variances for all we know could be more than 2 degrees going around the stone not to mention minor facet variances. Good point.

That is why it is ALWAYS advisable to have the stone checked out by a pro.


Rhino
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,327
You will note that my results are different (lower) Robin and Todd (can I call you guys RT since you are so close
) so I presumed you did not allow for the asymmetry (as Rhino did not.

I have noticed quite a few usages of DiamCalc where this has occurred.

I did them on default settings, so perhaps you enetered just one diameter - or stayed on the 6.00mm default.
It is also very easy to put a diameter in and if you are not careful with the order of entry, it can default back again.
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792

----------------
On 3/1/2003 5
1:11 AM Cut Nut wrote:
You will note that my results are different (lower) Robin and Todd (can I call you guys RT since you are so close
) so I presumed you did not allow for the asymmetry (as Rhino did not.

I have noticed quite a few usages of DiamCalc where this has occurred.

I did them on default settings, so perhaps you enetered just one diameter - or stayed on the 6.00mm default.
It is also very easy to put a diameter in and if you are not careful with the order of entry, it can default back again. ----------------
"RT" or NiceIce is fine by us... Those of you who know us, know that we're always together


We entered the dimensions just like they were provided "6.12-6.15x3.72" and locked the depth field... We've noticed that the program doesn't allow us to get full control of the girdle and weight fields as we go down the list... So we've been locking the fields for depth, table, crown angle, pavilion angle and letting the chips fall where they may for culet size, girdle thickness and weight since the program seems intent on taking control of those fields...

We've also been unable to get the program to hold our changes in the angles details tab for the minimum and maximum crown / pavilion angle measurements and the ones determined by the program do not match our OGI MS Results... What are we missing? Anyway, this may be why you're seeing as many DiamCalc uses that are less precise than you expect - looking forward to hearing "the fix".

Hey Gary, are you going to be at JCK Vegas? Perhaps we can get a "live demonstration" on this puppy! Um, that's a hint...

 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
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Messages
15,327
Happy to give a demo in June


Try this - run your cursor over girdle and also over the girdle stated thickness. There are options there - play with them and you will solve your problem. It also helps fully understand the Fred Cuellar warping problem.

Also go to advanced and see if you can find some more - then you will undersatnd how to model off round stones of 2 types
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792

----------------
It also helps fully understand the Fred Cuellar warping problem.
----------------
Fred Cuellar is warped? Why thank you Gary, we didn't realize that


Sometimes we kill even ourselves!
 

Spinning Head

Rough_Rock
Joined
Feb 24, 2003
Messages
10
As soon as I can get my hands on additional info I'll post it.

Thanks for responding too. I feel more comforable dropping $4-$5K on a car than a rock even with a geology background! Any help and suggestions I can get are welcome.
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792

----------------

Try this - run your cursor over girdle and also over the girdle stated thickness. There are options there - play with them and you will solve your problem.
----------------

This did solve the girdle and culet issues, thank you.

From the "cut quality" tab, how do I "implement" the fire and scintillation options which are currently grayed out?
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,327
Pay Sergey, Yuri and me half as much money as the GIA has squandered on cut studies and we will make the Fire and Scintillation parts work within a year


But after we have all the ingredients, that still will not tell us which is the best looking diamond, because the best light return will not occur with the best scintillation and fire. This is a hard game. As I said in another thread - like finding the perfecct woman / man. Or as is Leonid's fixation - the perfect Vodka.
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
DOH!!! Gary that is funny! So Leonid like his vodka huh?
 

Spinning Head

Rough_Rock
Joined
Feb 24, 2003
Messages
10
OK here is the additional info. Do you think a diamcalc can be done on this?

Next is the idealscope....

SARIN_AGS-3826401.gif
 

Rhino

Ideal_Rock
Trade
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Mar 28, 2001
Messages
6,272
If you don't mind me asking ... who took the pic? And if possible the person who ran the Sarin may be able to give you star/upper girdle ratio. That info would help too.

Rhino
 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792
The pavilion facets seem to be cut within a really tight tolerance, but the crown facets are pretty far out of whack in terms of their tolerance... This is actually an excellent example of Fred's "warped theory"... Not that any of our eyes would probably every pick up on it... If you don't mind, we're going to hold off on doing the DiamCalc analysis because we'd like to see what Garry comes up with on this puppy...
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
The combo of the angles seem just fine. In our LightScope when reds start to wash out the blacks this is indicative of light being pushed out at more of an angle that is not perpendicular to the table and usually results in poorer light return. I don't believe this is the case with this particular stone, just the photographer.
Showing these images without an explanation or correlation is a nice and noble attempt but meaningless but I guess better than nothing? It's kinda like showing a chart or a graph and asking ... so what do you think without knowing the data that that chart is based upon.

Judging from the #'s though and not so much the pic it seems like it'd be a stone with very good light return and overally brilliancy. However the variations I see at the arrow shafts indicate that you may indeed have a wacky hearts pattern. Is this being sold as an H&A?

Rhino
 

BrianTheCutter

Shiny_Rock
Joined
Jul 26, 2002
Messages
146
Cut Nut:
----------------
It is a very nice diamond.
The crown variance is about 1/5th as critical as pavilion variance - nothing to worry about.

I would be happy to sell or buy the stone

----------------
Thank you Garry


Robin & Todd Gray, NiceIce:
----------------
“The pavilion facets seem to be cut within a really tight tolerance, but the crown facets are pretty far out of whack in terms of their tolerance... This is actually an excellent example of Fred's "warped theory"... “
----------------
Rhino, GoodOldGold:
----------------
“However the variations I see at the arrow shafts indicate that you may indeed have a wacky hearts pattern. Is this being sold as an H&A?”
----------------
Madam and Gentlemen!

I don’t think there is anything wrong with this stone, in my professional opinion the hearts look pretty good to me, a standard that is consistent with A Cut Above whether from the new line or the old. Perfect H&A image is a guarantee that all the facets of the stone are in correct optical alignment.

Pavilion angle is the most important when it comes to the Hearts or the Arrows. Forgive me for been harsh (no disrespect was meant!) but your comments show a small gap in your knowledge when it comes to the art of Diamond Cut. Allow me to give you a couple of lessons.

Lesson 1: I believe Garry and Sergey used to explain this principle a while ago.

If you take the average of the opposite crown angels you will see that they average out correctly.

Example taken from the Sarin report

34.0° + 33.4° = 67.4° / 2 =33.7°
33.8° + 33.6° = 67.4° / 2 =33.7°
33.9° + 33.4° = 67.3° / 2 =33.65°
34.0° + 33.2° = 67.2° / 2 =33.6°

This is what tolerance is, gentlemen, this is the art of Diamond cutting a variance on 33.6 to 33.7, not going clock wise around the stone and comparing one to the next one or the lowest and the highest even though its only 8/10ths of a degree thinner than a hair on your head. Using this so called “tolerance”, is incorrect because it doesn’t reflect optical alignment of the opposite facets, which is crucial for optimizing the light performance of the diamond.

Again it’s the relationship of the opposite angels. In this particular diamond it is a result of working the stone to limit the amount of light leakage.

Lesson 2:

Note the consistency of the girdle: if this stone was not cut correctly the girdle would be wavy.

This particular stone is not New Line of “A Cut Above” because of the slight amount of light leakage.

It is also important to understand that in standard configuration DiamCalc cannot simulate light leakage for the stones with even distribution of the light return based on crown and pavilion angles only. All the minor facets should be taken into account.

Hope this helps
 

Spinning Head

Rough_Rock
Joined
Feb 24, 2003
Messages
10
So here is my final question regarding this stone:

Since the girdle is thin, is there a particular setting that I should use or stay away from?

Thank you all for your help on this.

 

niceice

Brilliant_Rock
Joined
Jan 29, 2003
Messages
1,792
Hey Brian, it's good to hear from you again! Thank you for pointing out how to average the measurements correctly! We're here to learn as much as we are to answer the questions that we can and we're always happy to admit we're wrong when we're wrong... The H&A pattern looks fabulous with very little variation in terms of size and shape... Looks like a winner to us! Better hurry up and buy it "spinninghead" 'cuz otherwise somebody else who's watching this thread might jump on it
 
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