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What makes these two diamonds perform differently?

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Date: 6/6/2009 10:40:28 PM
Author: strmrdr

Date: 6/6/2009 10:08:28 PM
Author: dreamer_dachsie



ETA I just noticed that the pavilion angles and % are identical in these two diamonds, and are not particularly shallow or steep I think, so the parameters at play here differentiating these two diamonds must be the tables (# 2 smaller), crowns (#2 higher), and lgfs (# 2 shorter).
primary difference is the lgf and size.
The crown differences make much less of a difference.
The LGF size difference is minimal, you think that would create a really noticeable difference?
 
Date: 6/6/2009 10:46:54 PM
Author: dreamer_dachsie


Date: 6/6/2009 10:40:28 PM
Author: strmrdr



Date: 6/6/2009 10:08:28 PM
Author: dreamer_dachsie



ETA I just noticed that the pavilion angles and % are identical in these two diamonds, and are not particularly shallow or steep I think, so the parameters at play here differentiating these two diamonds must be the tables (# 2 smaller), crowns (#2 higher), and lgfs (# 2 shorter).
primary difference is the lgf and size.
The crown differences make much less of a difference.
Good to know! I think finding another bigger diamond I like as much may be a challenge for me... I will need an expert to help me along when I pick it out for sure.
No, DD... all you will need are good numbers to start with and then your own eyes to confirm that you LOVE (or don't love) what you see.

I LOVE discussions like these, and I agree with everything that has been said. But I am still convinced that there are immeasurable nuances (don't we we call this the diamond's "personality"?) among stones and only the beholder can decide what they love or consider to be the most beautiful.

In other words, if two *identical* (by the numbers) stones could be found and compared, it is my humble opinion that each stone would still *look* and perform differently. Maybe the difference(s) would be imperceptible to the naked human eye... but maybe not.

BTW, DD, if I've missed it, please forgive... but what are the colors/clarities of the two stones?
 
Date: 6/7/2009 8:32:50 AM
Author: Lynn B



Date: 6/6/2009 10:46:54 PM
Author: dreamer_dachsie





Date: 6/6/2009 10:40:28 PM
Author: strmrdr






Date: 6/6/2009 10:08:28 PM
Author: dreamer_dachsie



ETA I just noticed that the pavilion angles and % are identical in these two diamonds, and are not particularly shallow or steep I think, so the parameters at play here differentiating these two diamonds must be the tables (# 2 smaller), crowns (#2 higher), and lgfs (# 2 shorter).
primary difference is the lgf and size.
The crown differences make much less of a difference.
Good to know! I think finding another bigger diamond I like as much may be a challenge for me... I will need an expert to help me along when I pick it out for sure.
No, DD... all you will need are good numbers to start with and then your own eyes to confirm that you LOVE (or don't love) what you see.

I LOVE discussions like these, and I agree with everything that has been said. But I am still convinced that there are immeasurable nuances (don't we we call this the diamond's 'personality'?) among stones and only the beholder can decide what they love or consider to be the most beautiful.

In other words, if two *identical* (by the numbers) stones could be found and compared, it is my humble opinion that each stone would still *look* and perform differently. Maybe the difference(s) would be imperceptible to the naked human eye... but maybe not.

BTW, DD, if I've missed it, please forgive... but what are the colors/clarities of the two stones?
Ditto, also I don't always think everything can come down to numbers or be explained as such, numbers and theories have their place I am the first to admit but sometimes the magic, nuances and beauty can't always be explained in this way. To me diamonds do have a distinct personality and character if well cut and sometimes the beauty or behaviour' just is' and can't always be explained in theory. Which I think is good to bear in mind sometimes!
 
With precision cutting and design diamonds it is possible to make 2 diamonds look the same to the eye.
You take 2 Infinity, ACA classic or the same make of gog h&a and compare them to the same with the same averages and size and compare them side by side they will look the same to the eye.
Matched sets have been a staple of the high end diamond market for a long time.
It is much easier to match small diamonds than large ones.

The thing is very very rarely is everything the same.
That is changing.

That said you take a .75ct diamond from any of the above and compare then to a 2.0ct of course they are going to look different.
The virtual facets are totally different sizes.
 
Small differences in the pavilion can make a huge difference in face up appearance.
This is a huge reason that GIA rounding the lgf% to 5% is a major joke.

It takes a much larger change in the crown to change the appearance to the degree that a small change in the pavilion will make.
 
Date: 6/7/2009 12:30:31 AM
Author: whatmeworry

...[edited quotes for space]

Dreamer, that''s a really good evaluation of the two diamonds from a consumer point of view. The reason I asked what the lighting conditions were was because after reading the earlier post I went out and played with some rocks in direct sunlight to compare fire. I think direct sunlight is a really good way to evaluate fire so I''m not sure I agree with the advice to not look at diamonds in direct sunlight. It sounds like some other ways are to shine beams against a wall or indirect low light. Now the key is how do you replicate it when you upgrade?
In this particular case, sunlight has definitely been the real discriminating environment. Do we sometimes tell people not to look at the diamon in direct sunlight? I suppose it will not really help you assess most other aspects of diamond light performance, since the diamond does go "dark" in strogn sunlight, but for fire it seemed to really polarize the performance of these two diamonds.

How to replicate. This will be hard because I am buying online from Canada... seeing the diamond in person before buying it won''t be a simple thing, nor would sending it back!
 
Here are the VF at the real relative size .75ct and 2ct with the exact same numbers.
Of course they are going to look different, look at the different size virtual facets.
Effective virtual facet size for any given lighting is not diamond size dependent.
The size VF that will be effective is the same(well close enough for this level) for a .75ct as a 2CT in any given lighting.
It will change with lighting. (attention AGS, take this into consideration)

The arrow heads on the 2ct are bigger than the arrow shafts on the .75ct.

75pcVS200ptVF.gif
 
Date: 6/7/2009 8:32:50 AM
Author: Lynn B

Date: 6/6/2009 10:46:54 PM
Author: dreamer_dachsie



Date: 6/6/2009 10:40:28 PM
Author: strmrdr




Date: 6/6/2009 10:08:28 PM
Author: dreamer_dachsie



ETA I just noticed that the pavilion angles and % are identical in these two diamonds, and are not particularly shallow or steep I think, so the parameters at play here differentiating these two diamonds must be the tables (# 2 smaller), crowns (#2 higher), and lgfs (# 2 shorter).
primary difference is the lgf and size.
The crown differences make much less of a difference.
Good to know! I think finding another bigger diamond I like as much may be a challenge for me... I will need an expert to help me along when I pick it out for sure.
No, DD... all you will need are good numbers to start with and then your own eyes to confirm that you LOVE (or don''t love) what you see.

I LOVE discussions like these, and I agree with everything that has been said. But I am still convinced that there are immeasurable nuances (don''t we we call this the diamond''s ''personality''?) among stones and only the beholder can decide what they love or consider to be the most beautiful.

In other words, if two *identical* (by the numbers) stones could be found and compared, it is my humble opinion that each stone would still *look* and perform differently. Maybe the difference(s) would be imperceptible to the naked human eye... but maybe not.

BTW, DD, if I''ve missed it, please forgive... but what are the colors/clarities of the two stones?
Oh I agree completely Lynn! I feel comfortbale now using my eyes to judge because I have lived with a few different diamonds for a while and I really know what I like and don''t like and what a great cut looks like (I am always hesitant to advice people to trust their eyes when they are new to diamonds and don''t have a good feel for how different cuts can look...)

Diamond 1 is J VS2 and Diamond 2 is K SI1
19.gif
Do you think think the color differences play into my preference? I do wonder if maybe I enjoy the warmth of my K more... it certainly shows more shades of white/cream when it scintillates (maybe also because it is bigger).
 
Date: 6/7/2009 8:47:40 AM
Author: Lorelei

Date: 6/7/2009 8:32:50 AM
Author: Lynn B



...[edited]

No, DD... all you will need are good numbers to start with and then your own eyes to confirm that you LOVE (or don''t love) what you see.

I LOVE discussions like these, and I agree with everything that has been said. But I am still convinced that there are immeasurable nuances (don''t we we call this the diamond''s ''personality''?) among stones and only the beholder can decide what they love or consider to be the most beautiful.

In other words, if two *identical* (by the numbers) stones could be found and compared, it is my humble opinion that each stone would still *look* and perform differently. Maybe the difference(s) would be imperceptible to the naked human eye... but maybe not.

BTW, DD, if I''ve missed it, please forgive... but what are the colors/clarities of the two stones?
Ditto, also I don''t always think everything can come down to numbers or be explained as such, numbers and theories have their place I am the first to admit but sometimes the magic, nuances and beauty can''t always be explained in this way. To me diamonds do have a distinct personality and character if well cut and sometimes the beauty or behaviour'' just is'' and can''t always be explained in theory. Which I think is good to bear in mind sometimes!
Diamond personality seems to be a larger issue when the diamond is a little larger, don''t you think? Because it is easier to see all the slight differences in performance on a larger surface area?

So here is my pickle. I am buying remotely from Canada... seeing the diamond in person before buying is a challege because shipping numerous times accross border is a challenge. Any solutions? This next upgrade will be my forever stone (in the 1.6ct range)
 
Date: 6/7/2009 10:08:54 AM
Author: dreamer_dachsie



So here is my pickle. I am buying remotely from Canada... seeing the diamond in person before buying is a challege because shipping numerous times accross border is a challenge. Any solutions? This next upgrade will be my forever stone (in the 1.6ct range)
The key here is communication and a knowledgeable vendor.
Brian and Jon are masters of this.
Wink is also in a different way.
Todd is kind of cross between Wink and Brian/Jon
 
Date: 6/7/2009 8:47:40 AM
Author: Lorelei

Ditto, also I don''t always think everything can come down to numbers or be explained as such, numbers and theories have their place I am the first to admit but sometimes the magic, nuances and beauty can''t always be explained in this way. To me diamonds do have a distinct personality and character if well cut and sometimes the beauty or behaviour'' just is'' and can''t always be explained in theory. Which I think is good to bear in mind sometimes!
There is nothing different between these 2 diamonds that cant be explained by virtual facets.
That science isn''t at the point that it can totally explain it doesn''t mean it wont some day.
 
I think that some posters here correctly referred to two possible reasons:

- One is the difference in size, and thus the difference in virtual facets size, and the likelihood changing from you observing fire,
- A second reason is the small difference in LGF-length, although I wonder if that measured difference is meaningful.

However, a major reason, I think is that one is an ACA, while the other is Expert Selection. I am sure that Whiteflash has strict rules for a stone obtaining the ACA-brand, and not all are visible for us. Your second stone obtained that ACA-label for a reason, and it is highly likely that the difference in performance is due to a specific brand-attribute. After all, the measurements you have are all averages and the pictures are still and face-up. You get a big part of the story, but experiencing a diamond live gives you much more information on a stone''s performance.

Live long,
 
The images do show slight differences between the diamonds. Our eyesand minds cannot predict exactly how these differences will manifest themselves in normal viewing, but we can say that we''d expect the diamonds not to look identical. How they compare to one another is the difficult thing for use to predict or toeven describe in words. We can say they look "different'', but that is about all we can say for sure.

You can facet diamonds in ways which produce quite identical facet and parametric measures and yet still have differences of appearance based on their different relative size and nuance differences which go un-measured or remain less well seen or unseen by the measuring devices.

This is why grading of diamonds by direct assessment of performance surpasses all manner of predictive grading. We have come about as far as we can with predictive models and predictive grading. Some of these sytems are very good, but they are not perfect and never will be. We can do the final part only by direct assessment of each individual component of light behavior. Currently, we are still in the process of deciding what light performance attributes we will use to measure in order to a non-subjective grade. The market and the scientists will work this out in the coming months or next couple of years, I suppose. Until then, we will use the tools which we have agreed upon to help us direct folks to the best cut diamonds with a reasonable degree of certainty, yet with the knowledge that there are still more refinements to come.

I would expect the top sources of finely cut diamonds to continue to look at the technological solutions which are being, or will be offered to them. At some point we will have agreed upon, objective tools which grade the cut better than what we have right now. As good as we have it today, we can and likely will, do even better.

These revisions will lead to even finer cuts and better consistency within brands. I see no downside to the process although it seems to take so long to get there.
 
Date: 6/8/2009 11:14:49 AM
Author: oldminer
The images do show slight differences between the diamonds. Our eyesand minds cannot predict exactly how these differences will manifest themselves in normal viewing, but we can say that we''d expect the diamonds not to look identical. How they compare to one another is the difficult thing for use to predict or toeven describe in words. We can say they look ''different'', but that is about all we can say for sure.

Keep in mind however that the lighting conditions may have been different when the picture of each diamond was taken. Lighting conditions, time of day, the amount of direct or indirect light available in the room at the time the picture was taken, etc. will have a direct effect on the images of each diamond. Clarity photographs should be used to obtain a reference to the inclusions and their visibility within the diamond and not as a reference to the visual potential of a diamond for this reason. Additional variances in things like the focal depth and F-stop used at the time each photograph is taken will also have a dramatic effect on the appearance of the diamond in the photograph.

The length of the lower girdle facets and stars definitely will have an effect on the visual performance of the diamond, but as stated by Strmrdr the size of the virtual facets is no doubt a factor here... And then there is the issue of whether the original diamond was recently viewed sparkling clean or happened to have a little bit of haze from daily life on it. So many factors come into play when considering slight variances in visual performance, but it makes for a fun read! Congratulations on your new diamond, it sounds gorgeous
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Date: 6/7/2009 10:14:57 AM
Author: strmrdr
Date: 6/7/2009 10:08:54 AM
The key here is communication and a knowledgeable vendor.

Brian and Jon are masters of this.
Wink is also in a different way.
Todd is kind of cross between Wink and Brian/Jon.

I''m a what?!?! Seriously, I know what you''re trying to say Strmrdr but that last sentence just sounds wrong
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I''ve been following this thread with interest because I''m about to come into possession of Dreamer''s Diamond #1 for my engagement ring. It''s arriving TODAY! Then we get to find a setting. Then you get to see EVEN MORE pictures of this particular diamond! As if you aren''t sick of it already.
31.gif


I am pleased to see that everybody has noted it''s a great diamond. Maybe someday I''ll be able to upgrade to an ACA too, but in the meantime it''s good to know I have a quality stone on my finger since this was our first diamond buying experience (and I picked the stone out all by myself).
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