DiamCalc model?

[anton84]

I would greatly appreciate it if someone with DiamCalc could generate me a model for the following stone:

1.04ct
Total Depth %: 60.7
Table: 59%
Crown Height: 14.3%
Crown Angle: 35.2
Star Length: 50%
Pavillion Depth: 43%
Pavilion Angle: 40.9
Lower Half Length: 80%
Girdle Thickness- Thin to Medium
Girdle Finish: Faceted
Cutless: none



Thanks in advance!

 

[Lorelei]

Date: 1/12/2009 9:06:08 AM
Author:anton84
I would greatly appreciate it if someone with DiamCalc could generate me a model for the following stone:

1.04ct
Total Depth %: 60.7
Table: 59%
Crown Height: 14.3%
Crown Angle: 35.2
Star Length: 50%
Pavillion Depth: 43%
Pavilion Angle: 40.9
Lower Half Length: 80%
Girdle Thickness- Thin to Medium
Girdle Finish: Faceted
Cutless: none



Thanks in advance!

Hi Anton and welcome,

Someone might be able to do it for you, but can you ask for an Idealscope image of the diamond? This might be more useful than a computer simulation, especially as it is around what we term steep deep territory with the angles. Does the diamond have a grading report such as GIA?

 

[anton84]

I''ve heard the term steep/deep and I know what it means (numerically), but when you say it would be better to than a computer simulation especially because of this, is this because computer simulations start to break down with diamonds at these parameters? Are they usually over or under estimating the performance, or does it really just depend on the diamond?

I am unfortunately unable to get an idealscope of the diamond

, but it is GIA cert''d

Thanks for the reply

 

[Lorelei]

Date: 1/12/2009 9:52:57 AM
Author: anton84
I've heard the term steep/deep and I know what it means (numerically), but when you say it would be better to than a computer simulation especially because of this, is this because computer simulations start to break down with diamonds at these parameters? Are they usually over or under estimating the performance, or does it really just depend on the diamond?

I am unfortunately unable to get an idealscope of the diamond

, but it is GIA cert'd

Thanks for the reply

The experts have often said that an Idealscope image is a more accurate representation of a diamond as it is an image of the diamond itself rather than a simulation - someone like Storm will be better able to advise than me or one of the others who are more familiar with this programme as to how useful DiamCalc would be in this case.

Hang tight and I will try to page Storm or someone who can answer more in depth concerning DiamCalc, how it pertains to GIA proportions etc.

As to the diamond it is entering steep deep zone as we are aware and the table is a little bit larger than some we see here, have you seen the diamond in person, or is it with an online vendor?

Do you have the diameter measurements and polish and symmetry grades also please?

 

[anton84]

I have seen the diamond in person, but to be honest I have no idea what I''m supposed to be looking for. I''ve read up a *lot* on this stuff, but there''s enormous amounts of experience I lack to do anything in person.

Yes, it''s excellent/excellent for the two qualities you asked for, as well as measuring 6.53x6.58mm

 

[Lorelei]

Date: 1/12/2009 10:13:56 AM
Author: anton84
I have seen the diamond in person, but to be honest I have no idea what I'm supposed to be looking for. I've read up a *lot* on this stuff, but there's enormous amounts of experience I lack to do anything in person.

Yes, it's excellent/excellent for the two qualities you asked for, as well as measuring 6.53x6.58mm

Thanks, that all falls within good range.

I know it is difficult when you are new to diamonds, but there are a couple of things you can do to help. So you have a baseline comparison, see if you can look at some AGS0 cut grade ( Jareds sell them) or Hearts on Fire brand so you are comparing this one to well cut stones. Also ask if you can view any diamonds you like away from the store lights, jewellery store lighting can make even poorly cut diamonds sparkle, so plain daylight gives you a more realistic picture.

Also you can buy an Idealscope inexpensively and check any diamonds out that you are interested in yourself. The main concern with steep deeps is light leakage. This can show as paler patches on IS images ( see chart) and on the diamond itself you may notice dark areas, often around the table area. This is also why checking a diamond out away from store lights is a good idea to make any leakage reveal itself. As GIA round the numbers it is difficult to predict with borderline steep deeps ( depending on which way the numbers are rounded) if the diamond will be perfectly fine, whether it shows leakage and whether it is visible to the human eye, or if so to what extent it affects the diamond. So IS plus in person evaluation plus an impartial opinion from an independant appraiser can be very useful.

http://www.ideal-scope.com/cart_zoom_item.asp?Id=2&ShowAdd=Y

Chart so you can interpret the results of IS - http://www.ideal-scope.com/using_reference_chart.asp

 

[John P]

Date: 1/12/2009 9:52:57 AM
Author: anton84
I've heard the term steep/deep and I know what it means (numerically), but when you say it would be better to than a computer simulation especially because of this, is this because computer simulations start to break down with diamonds at these parameters? Are they usually over or under estimating the performance, or does it really just depend on the diamond?

Hi Anton.

The basic numbers aren't enough to create an accurate simulation. Your CA of 35.2, for instance, is an average of 8 numbes. The lower half % is an average os 16. The computer would assume a perfect wire-frame for those, which doesn't exist in reality. Additionally there is degree of cut precision/optical symmetry, brillianteering variations, girdle wave...3D realities which are not described in 2D numbers.

Using the basics you provided a round brilliant could have all of the looks below - or many others (and I did not see your dimensions post so I used identical length-width mm to start with).

 

[John P]

Date: 1/12/2009 9:52:57 AM
Author: anton84

I am unfortunately unable to get an idealscope of the diamond

, but it is GIA cert''d

GIA rounds CA and PA in a manner that would not report 35.2/40.9. Did you get the proportions data from a separate report or scan Anton?

 

[anton84]

Thank you both so much for your help!

When I held the diamond up to the light in a certain way I was able to see a very (IMO) symmetrical arrow pattern. I''ve read that''s a good thing, although is that enough to assume that it is indeed fairly symmetrical?

The three pictures you posted, out of curiosity, what variables were you playing with to generate all three?

 

[Lorelei]

Date: 1/12/2009 10:58:12 AM
Author: John Pollard

Date: 1/12/2009 9:52:57 AM
Author: anton84

I am unfortunately unable to get an idealscope of the diamond

, but it is GIA cert''d

GIA rounds CA and PA in a manner that would not report 35.2/40.9. Did you get the proportions data from a separate report or scan Anton?

Thanks Sir J for your assistance!

I was curious about those measurements too and where they came from....

 

[John P]

Date: 1/12/2009 11:04:39 AM
Author: anton84
Thank you both so much for your help!

The three pictures you posted, out of curiosity, what variables were you playing with to generate all three?

You''re welcome. The first sim is a perfect wireframe using the measurments you indicated. I changed individual angles on mains and break facets in the second sim without altering 40.9/35.2 average, then gave it more pedestrian optical symmetry. I started from scratch with the third, added slight digging on pavilion and crown breaks, and altered optical symmetry again.

Precise optical symmetry can improve contrast but you need an ideal-scope, ASET or 3D scan to know how far individual angles stray from the averages. It depends on how far you want to get into all this. You''re not looking at a stone with ''bad'' measurements, if that''s all you want to know.

 

[John P]

Date: 1/12/2009 11:06:20 AM
Author: Lorelei

Thanks Sir J for your assistance!

I was curious about those measurements too and where they came from....

You're welcome. I was waiting for Strm to chime, since he's typically Johnny on the spot. I've been waiting for the opp to say 'kewl' or 'kicken' for you in the thread but it hasn't popped. I could have just said 'Welcome' here....but if I mimic him he could just make his posts 10X longer to mimic me.

Still curious about the numbers too. Oh Anton? Where did your 40.9/35.2 come from, kind sir?

 

[Lorelei]

Date: 1/12/2009 11:18:47 AM
Author: John Pollard

Date: 1/12/2009 11:06:20 AM
Author: Lorelei

Thanks Sir J for your assistance!

I was curious about those measurements too and where they came from....

You''re welcome. I was waiting for Strm to chime, since he''s typically Johnny on the spot. I''ve been waiting for the opp to say ''kewl'' or ''kicken'' for you in the thread but it hasn''t popped. I could have just said ''Welcome'' here....but if I mimic him he could just make his posts 10X longer to mimic me.

Still curious about the numbers too. Oh Anton? Where did your 40.9/35.2 come from, kind sir?

ROFL!!!!

 

[strmrdr]

Date: 1/12/2009 11:18:47 AM
Author: John Pollard

Date: 1/12/2009 11:06:20 AM

Author: Lorelei


Thanks Sir J for your assistance!


I was curious about those measurements too and where they came from....

You're welcome. I was waiting for Strm to chime, since he's typically Johnny on the spot. I've been waiting for the opp to say 'kewl' or 'kicken' for you in the thread but it hasn't popped. I could have just said 'Welcome' here....but if I mimic him he could just make his posts 10X longer to mimic me.

Still curious about the numbers too. Oh Anton? Where did your 40.9/35.2 come from, kind sir?

lol, I'm down and out with the flu. :{
This is the first I saw this thread and see ya have it under control.

 

[John P]

Date: 1/12/2009 11:29:09 AM
Author: strmrdr

lol, I''m down and out with the flu. :{
This is the first I saw this thread and see ya have it under control.

And that from the king of kontrol... crikey you must be feeling bad.

Sincerely sorry to hear it Karl.
Warmth and fluids dude...don''t go posting advice on cough syrup...we''re here if you need cyber-soup for the soul!

Oh, and disinfect your mouse more often.

 

[anton84]

The measurements came from a Tiffany cert (I know I know I know about the markup )

I had read that over 1ct they are cert''d by GIA, but I guess that''s not accurate from what you guys are saying here.

Yes my main concern was to ensure that those weren''t bad numbers. I am relieved that they aren''t

 

[John P]

Date: 1/12/2009 12:16:00 PM
Author: anton84
The measurements came from a Tiffany cert (I know I know I know about the markup )

I had read that over 1ct they are cert'd by GIA, but I guess that's not accurate from what you guys are saying here.

Yes my main concern was to ensure that those weren't bad numbers. I am relieved that they aren't

Table is on the large side for Tiff (while still in the GIA 'small' category globally) ergo crown ht is near the lower side of their range, but the angle averages are good.

 

[WinkHPD]

Date: 1/12/2009 11:29:09 AM
Author: strmrdr

Date: 1/12/2009 11:18:47 AM
Author: John Pollard

Date: 1/12/2009 11:06:20 AM

Author: Lorelei


Thanks Sir J for your assistance!


I was curious about those measurements too and where they came from....

You''re welcome. I was waiting for Strm to chime, since he''s typically Johnny on the spot. I''ve been waiting for the opp to say ''kewl'' or ''kicken'' for you in the thread but it hasn''t popped. I could have just said ''Welcome'' here....but if I mimic him he could just make his posts 10X longer to mimic me.

Still curious about the numbers too. Oh Anton? Where did your 40.9/35.2 come from, kind sir?

lol, I''m down and out with the flu. :{
This is the first I saw this thread and see ya have it under control.

Bummer dude! I am NOT KEWL with my Storm being sickly!

Get well quickly, you are needed at the diamond front!

Wink

 

[Lorelei]

Date: 1/12/2009 1:45:00 PM
Author: Wink

Date: 1/12/2009 11:29:09 AM
Author: strmrdr

Date: 1/12/2009 11:18:47 AM
Author: John Pollard

Date: 1/12/2009 11:06:20 AM

Author: Lorelei


Thanks Sir J for your assistance!


I was curious about those measurements too and where they came from....

You''re welcome. I was waiting for Strm to chime, since he''s typically Johnny on the spot. I''ve been waiting for the opp to say ''kewl'' or ''kicken'' for you in the thread but it hasn''t popped. I could have just said ''Welcome'' here....but if I mimic him he could just make his posts 10X longer to mimic me.

Still curious about the numbers too. Oh Anton? Where did your 40.9/35.2 come from, kind sir?

lol, I''m down and out with the flu. :{
This is the first I saw this thread and see ya have it under control.

Bummer dude! I am NOT KEWL with my Storm being sickly!

Get well quickly, you are needed at the diamond front!

Wink

I quite agree, it SUX that our Stormy is sickly!

 

[anton84]

Date: 1/12/2009 12:41:05 PM
Author: John Pollard

Date: 1/12/2009 12:16:00 PM

Author: anton84

The measurements came from a Tiffany cert (I know I know I know about the markup )


I had read that over 1ct they are cert''d by GIA, but I guess that''s not accurate from what you guys are saying here.


Yes my main concern was to ensure that those weren''t bad numbers. I am relieved that they aren''t

Table is on the large side for Tiff (while still in the GIA ''small'' category globally) ergo crown ht is near the lower side of their range, but the angle averages are good.

When you say table is on large side crown ht is near lower side what does this mean from a visual perspective? I mean, I know it means the table is larger and the crown is lower But what effect would it have on someone who doesn''t know anything about diamonds. Would they notice anything different? Or is it just a numerical difference that no one inexperienced will notice?

 

[John P]

Date: 1/12/2009 2:01:07 PM
Author: anton84

Date: 1/12/2009 12:41:05 PM
Author: John Pollard


Table is on the large side for Tiff (while still in the GIA ''small'' category globally) ergo crown ht is near the lower side of their range, but the angle averages are good.

When you say table is on large side crown ht is near lower side what does this mean from a visual perspective? I mean, I know it means the table is larger and the crown is lower But what effect would it have on someone who doesn''t know anything about diamonds. Would they notice anything different? Or is it just a numerical difference that no one inexperienced will notice?

More the highlighted. Through a broad range of lighting conditions a little less fire is predicted in the balance of visual qualities than the ''average'' T&Co round. The vast majority of people would be hard pressed to see that without it being pointed out, and it would require observation in different illumination panoramas. It''s like the difference between AGS0 versus 1 or 2.

 

[anton84]

You guys have been an immense help and I''ve learned a lot! Thank you so much for your time!

 

[anton84]

Hey John, I hate to be a bother (don''t mind saying no) but I''ve seen diamcalc models that sometimes include numbers that hover around 1? Like light return, leakage, etc. Would you mind posting those as well for the model you ran first (the most symmetrical one). I''m mostly just curious because I have an unquenchable thirst for this kind of knowledge

 

[John P]

Date: 1/12/2009 3:30:25 PM
Author: anton84
Hey John, I hate to be a bother (don't mind saying no) but I've seen diamcalc models that sometimes include numbers that hover around 1? Like light return, leakage, etc. Would you mind posting those as well for the model you ran first (the most symmetrical one). I'm mostly just curious because I have an unquenchable thirst for this kind of knowledge

No bother. It's on the border of Ideal and Excellent. The cut guidelines AGS provide to manufacturers for 6-8mm stones predict that 59, 40.9, 35.2 will receive AGS2. Those guides predict conservatively. If minor facets, cut precision and brillianteering all harmonize to help its performance when measured in 3D it could go higher. If those factors are uncomplimentary or imprecise it could go the other way. No firm answer without a scan so you may still be thirsty.

Based on its 2D measurements GIA would give it EX.

 

[strmrdr]

I think anton84 may be talking about the DC light return numbers I sometimes post but could be wrong.
Im off to lay down for a nap or I would post them.

 

[anton84]

Date: 1/12/2009 3:56:22 PM
Author: strmrdr
I think anton84 may be talking about the DC light return numbers I sometimes post but could be wrong.

Im off to lay down for a nap or I would post them.

I think that''s it. I saw something like this:

Light Return (mono): Very Good (0.99)
Light Return (stereo): Very Good (0.99)
(Non) Leakage (mono): Very Good (0.9
(Non) Leakage (stereo): Very Good (0.96)
Contrast: Very Good (0.99)
(Non) Fish Eye: Very Good (1.00)

On an older thread and was wondering what this diamond''s would look like.

 

[anton84]

I guess in addition to the DC light return numbers request above I have yet another question (again with the whole, thirst for knowledge thing )

I have read that angles are more accurate than depths, and that this is because the depth %''s are usually rounded. However, in the certificate I have it appears the depth %''s are not rounded to whole numbers are are instead rounded to the neared .1% (the 43% is written as 43.0% and the other as 14.3%)

Knowing that, I had expected to have fairly accurate numbers when I did the math. When I did the trig, however, the angles come out to 34.9 (vs 35.2) and 40.7 (vs 40.9). I''m of the understanding that these can make a pretty big difference in light return (or maybe not that big...)

Any ideas why the numbers wouldn''t work out to be accurate? Is the .1% rounding for the depth % still too inaccurate? It seems odd that these numbers would be in such wide conflict.

 

[Garry H (Cut Nut)]

Date: 1/13/2009 2:52:21 PM
Author: anton84
I guess in addition to the DC light return numbers request above I have yet another question (again with the whole, thirst for knowledge thing )

I have read that angles are more accurate than depths, and that this is because the depth %''s are usually rounded. However, in the certificate I have it appears the depth %''s are not rounded to whole numbers are are instead rounded to the neared .1% (the 43% is written as 43.0% and the other as 14.3%)

Knowing that, I had expected to have fairly accurate numbers when I did the math. When I did the trig, however, the angles come out to 34.9 (vs 35.2) and 40.7 (vs 40.9). I''m of the understanding that these can make a pretty big difference in light return (or maybe not that big...)

Any ideas why the numbers wouldn''t work out to be accurate? Is the .1% rounding for the depth % still too inaccurate? It seems odd that these numbers would be in such wide conflict.

scanners measure angles better than depths

 

[anton84]

Date: 1/13/2009 4:53:27 PM
Author: Garry H (Cut Nut)

Date: 1/13/2009 2:52:21 PM

Author: anton84

I guess in addition to the DC light return numbers request above I have yet another question (again with the whole, thirst for knowledge thing )


I have read that angles are more accurate than depths, and that this is because the depth %''s are usually rounded. However, in the certificate I have it appears the depth %''s are not rounded to whole numbers are are instead rounded to the neared .1% (the 43% is written as 43.0% and the other as 14.3%)


Knowing that, I had expected to have fairly accurate numbers when I did the math. When I did the trig, however, the angles come out to 34.9 (vs 35.2) and 40.7 (vs 40.9). I''m of the understanding that these can make a pretty big difference in light return (or maybe not that big...)


Any ideas why the numbers wouldn''t work out to be accurate? Is the .1% rounding for the depth % still too inaccurate? It seems odd that these numbers would be in such wide conflict.

scanners measure angles better than depths

That makes sense then, I knew something had to be off. Thanks

 

[John P]

Date: 1/13/2009 2:52:21 PM
Author: anton84
I guess in addition to the DC light return numbers request above I have yet another question (again with the whole, thirst for knowledge thing )

I have read that angles are more accurate than depths, and that this is because the depth %''s are usually rounded. However, in the certificate I have it appears the depth %''s are not rounded to whole numbers are are instead rounded to the neared .1% (the 43% is written as 43.0% and the other as 14.3%)

Knowing that, I had expected to have fairly accurate numbers when I did the math. When I did the trig, however, the angles come out to 34.9 (vs 35.2) and 40.7 (vs 40.9). I''m of the understanding that these can make a pretty big difference in light return (or maybe not that big...)

Any ideas why the numbers wouldn''t work out to be accurate? Is the .1% rounding for the depth % still too inaccurate? It seems odd that these numbers would be in such wide conflict.

Re: angles vs height...what Garry said. The most common non-contact scanners have a stated error of +/- up to 0.2 degrees. When calibrated and run carefully at hi-res they are generally more reliable (especially the phenomenal but rare Octonus scanner) but it goes to illustrate how minute all of these details really are.

DC light return numbers: I have not been blessed with the greatness of DC3, but here are numbers from ye auld DC 2.8, below. I give these because I know Strm would do it but is incapacitated right now - here''s hoping you mend soon Karl. They were generated from a perfect wire-frame, minus the mm dimensions you gave, so they are not specific - I trust we''ve hammered that point home.