Which CBI 0.5-E-VS1?

[Aimyr]

Hi everyone! I´m back again and this time I´m ready to take the plunge!
We´ve decided on a 0.5 E VS1 for her ring and there are 4 options to pick from (no need to pick out anything else, these are our perfect specs)

I usually feel like these threads are a bit silly since the differences are almost negligible in a selection this narrow... I guess it doesn´t really matter which one I pick since all of them should be good but I was wondering if there´s a favorite after all and why? (There´s always more to learn!)
The hearts seem skewed in some of them, is that just bad photography? I thought these were supposed to be superbly cut?

1) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9765
2) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9770
3) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9773
4) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9819

Thank you! The ending is in sight!

 

[Lorelei]

Hi everyone! I´m back again and this time I´m ready to take the plunge!
We´ve decided on a 0.5 E VS1 for her ring and there are 4 options to pick from (no need to pick out anything else, these are our perfect specs)

I usually feel like these threads are a bit silly since the differences are almost negligible in a selection this narrow... I guess it doesn´t really matter which one I pick since all of them should be good but I was wondering if there´s a favorite after all and why? (There´s always more to learn!)
The hearts seem skewed in some of them, is that just bad photography? I thought these were supposed to be superbly cut?

1) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9765
2) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9770
3) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9773
4) https://www.hpdiamonds.com/en-us/diamonddetail/HPD9819

Thank you! The ending is in sight!

Hi Aimyr,

I'm not seeing anything up with the images personally. You could pick any and be delighted and yes, these are among the finest cut diamonds in the world! Sometimes the images are tilted slightly as you suggest and maybe you have very sharp eyes and are picking up on this but I assure you, you'll have no concerns with the actual diamonds!

 

[doberman]

Honestly I don't think you can go wrong picking any of them, and I don't see one of them as any "better" than the others. It's a totally level playing field.

 

[natasha-cupcake]

Eenee, meenee, miney, mo?

Honestly, I don't think there would be any perceptible differences between them. That's the beauty of a CBI. Pick your size, color and clarity and you can be sure that you're getting the best possible cut. Of course, if you had the opportunity to see all four in person, one might strike you as having a certain "personality", or simply "speak to you". If you're buying online from HPD, you can always ask Wink or Melissa to give you some input on whether or not there are any individual "personality" differences between the stones.

 

[OoohShiny]

2 and 3 have completely clean tables in terms of inclusion plots on the certificates, so are even more 'mind-clean' than the VS1 should mean they are in real life and would be attractive to me. (I am a clarity freak lol)

That said, 1 has 76% LGFs so might have slightly more 'fire' than the other three (which have 77% LGFs) but they should really be much of a muchness. 1 and 4 also have smaller tables, but they're all under 56.2%, which is already at the smaller end of the PS-recommended 55-59% range!

In short, they will all be awesome It's just different nuances that might appeal!

 

[Lorelei]

2 and 3 have completely clean tables in terms of inclusion plots on the certificates, so are even more 'mind-clean' than the VS1 should mean they are in real life and would be attractive to me. (I am a clarity freak lol)

 

[marcy]

I think any of them would be gorgeous.

 

[Aimyr]

Thanks for the input!

While we´re discussing minutia. Is the difference in contrast under the table (the blue in between the base of the arrows) noticeable and contributes to a darker center? Or is that just a fluke of the computer model? I´m a big fan of contrast but the arrows themselves offer enough of that so if it actually is that noticeable I´d lean to the one that has a less muddy center.

 

[Dancing Fire]

Pick a # out of a hat or you can make a 4 stone ring!... They are all beautiful top cut stones.. . If I must pick one i'll go with #1.

 

[YoLaL]

Left one is better contrast and more appealing.

Thanks for the input!

While we´re discussing minutia. Is the difference in contrast under the table (the blue in between the base of the arrows) noticeable and contributes to a darker center? Or is that just a fluke of the computer model? I´m a big fan of contrast but the arrows themselves offer enough of that so if it actually is that noticeable I´d lean to the one that has a less muddy center.

 

[Lorelei]

Thanks for the input!

While we´re discussing minutia. Is the difference in contrast under the table (the blue in between the base of the arrows) noticeable and contributes to a darker center? Or is that just a fluke of the computer model? I´m a big fan of contrast but the arrows themselves offer enough of that so if it actually is that noticeable I´d lean to the one that has a less muddy center.

These are computer generated images, not actual ASET of the stones in question.

 

[Aimyr]

These are computer generated images, not actual ASET of the stones in question.

Are these computer images AGS supplies generated from an actual scan of the diamond (and thus fairly accurate), or is this just an approximation based on a couple of averaged values? Basically, is there any value in using these to make a choice?

I´m probably overthinking it though

 

[Dancing Fire]

IMO, the actual ASET is more accurate.

 

[bmfang]

Are these computer images AGS supplies generated from an actual scan of the diamond (and thus fairly accurate), or is this just an approximation based on a couple of averaged values? Basically, is there any value in using these to make a choice?

I´m probably overthinking it though

These are derived from an actual scan of the stone however there is scanner deviation. So if there is nothing else to make a decision on, the computer generated ASETs are useful. If they will provide actual ASET’s they will usually correlate well, but in my experience based on the limited stones I have, sometimes the additional contrast at the base of the arrow heads may not show up in the actual ASET photo.

 

[John P]

Thanks for the input!

While we´re discussing minutia. Is the difference in contrast under the table (the blue in between the base of the arrows) noticeable and contributes to a darker center? Or is that just a fluke of the computer model? I´m a big fan of contrast but the arrows themselves offer enough of that so if it actually is that noticeable I´d lean to the one that has a less muddy center.

You've received good input above. To elaborate, this happens for several reasons.

1. Computer modeling doesn’t always faithfully reproduce micro-levels of cutting precision.
2. AGSL uses a different degree of obscuration/obstruction (blue) in the cones they produce for ASET viewers versus the degree used for computer modeling, which can be confusing.
3. Not germane to our setup, but on this topic: AGSL ASET viewers use a black background, as do most photo setups, but the computer model projects backlighting. That tends to emphasize contrast leakage and lower angular draw (greens) along facet junctions in some cases - just in case anyone wondered about that.

Back in 2005, when AGS introduced the ASET-based metric, we opted for a backlit ASET setup in an effort to be uniform with the lab. Over time we’ve learned a lot. Simply put, the differences between actual images and computer-generated imprints remain difficult to bridge.

In the lab’s defense: Many traditional jewelers using AGS reports just want the “Ideal” pedigree for their clients. They may not use the grading report or discuss ASET when presenting the diamond. I regularly hear of jewelers who deliver a finished ring and, months or years later, discover the grading report in their cabinet, never delivered.

That doesn’t make questions like @Aimyr 's less important but it's a high level of scrutiny; there are career jewelers who will never discuss this topic. In that sense I picture the kind folks at AGSL fielding our inquiries with the same patience as a fine chef being asked to make the garnishes on a certain customer’s order all perfectly symmetrical.

 

[flyingpig]

Thanks for the input!
While we´re discussing minutia. Is the difference in contrast under the table (the blue in between the base of the arrows) noticeable and contributes to a darker center? Or is that just a fluke of the computer model? I´m a big fan of contrast but the arrows themselves offer enough of that so if it actually is that noticeable I´d lean to the one that has a less muddy center.

AGSL uses a different degree of obscuration/obstruction (blue) in the cones they produce for ASET viewers versus the degree used for computer modeling, which can be confusing.

As John Pollard explained, don't worry about the "darker" and "muddy" center. You don't see that in the actual ASET. It may also have something to do with one stone having 40.8 PA and the other having 40.7.
When you have a slightly high PA, you draw and reflect light from higher angles. That's why you see a bit of red right in the middle instead of just green, and a bit of blue instead of just red.
This article talks about table reflection. But, a simiilar explanation can be applied to contrast and "muddy center"
https://www.whiteflash.com/about-di...n/aset---table-reflection-whiteflash-1420.htm

Here is an example of super ideal with "muddy" centre. Note PA=40.9
http://www.agslab.com/pdf_sync_reports/104098562008-PGRH.PDF

 

[John P]

...It may also have something to do with one stone having 40.8 PA and the other having 40.7. When you have a slightly high PA, you draw and reflect light from higher angles. That's why you see a bit of red right in the middle instead of just green, and a bit of blue instead of just red.

All things equal that's spot-on. However, the good information in the table-reflection article you linked applies to ASET 30 live views/photos but not standard AGSL reports: By using ASET 33.5 in computer modeling used to generate their report-imprints the demarcation changes, and that can change the table-reflection color seen IRL as opposed to what appears on the report. This has become an added bullet point of (sometimes) explanation in our showroom presentations.

 

[Aimyr]

Thanks for that in-depth reply @John Pollard and everyone else, always more to learn!
I have contacted my jeweler (in europe), who recently opened an account with CBI, and they said they could only get me the stone we´ve been discussing on here, stone #4. The information regarding the ASET/computer model eased my mind for the most part but failed to reassure me wholly and I think I figured out why I´m bothered by this stone.

After months of looking at CBI stones I´ve gotten quite used to their look (or photo setup) and was always drawn to the symmetry. However this stone didn´t wow me and I think I know why after staring at it for a bit. If you look at the "gap" in between the star and bezel facets, the dark outline if you will, it´s not even-width and well defined all around. It´s also visible in the ASET, where red touches red instead of a white gap. I know I would never be able to tell IRL but since I have never observed this in the other ones it´s hard to let it go.

I have great trust in the brand so there´s probably a good reason for this one as well but I´d like to learn what´s going on here! I totally understand your point about the high level of scrutiny though but it´s hard to stop asking questions nomatter how detailed or silly because this is so incredibly interesting to me !

 

[John P]

@Aimyr you're very welcome. Your questions are absolutely useful in adding to the collective information here.

One reason for those detail-differences relates to backlighting, briefly mentioned as item #3 in this post above. The backlighting is stronger in the left image (to the point of washout). Backlighting strength can vary due to new bulbs, lens proximity or exposure settings. Stronger backlight emphasizes draw of light from low angles such as the star-facet junctions. Those are the lines you drew in red on your wire-frame example. The diamond on the right also shows some off-axis between table facet and camera lens. Such tilt, combined with softer backlight, can create those red-on-red areas you inquired about.

The images were taken three months apart. Some details in the photo setup may have shifted, but I'm confident that the diamonds are identical performance twins.

 

[flyingpig]

Just to elaborate a bit, any tilt or any misalignment can make a diamond appear completely differently.
It is important note that ASET consists of three distinctive zones that very abruptly and unrealistically transitions at 45 and 75 degrees. Those facets that draws and reflect light from 45ish or 75ish degrees are extremely sensitive to any tilt.

https://www.pricescope.com/community/threads/dyi-aset-nerdy-stuff-ver-2-0.234343/
See how the green area you mentioned enlarges as I increase the green cylinder by 1~2mm (photo #3)

Diamond photography is time-consuming and delicate process and it is whole another topic.

 

[TreeScientist]

Thanks @John Pollard, another informative post as always. Good to know the differences between the computer-generated ASETs and actual ASET images.

Regarding the obstruction surrounding the arrows, I've read that, in addition to a steeper pavilion angle above 40.8, the length of the star facets also contributes to this obstruction around the arrows. It's outlined in this article in the 5th bullet point:
http://www.heartsandarrows.com/hearts-arrows-diamond-ideal-cut-dna.aspx

Basically, steeper pavilion angles of >40.8, combined with longer star lengths >50%, can create white reflections that alter the appearance of the arrow pattern. This is why it's best to stick with star lengths around 50% or lower, particularly in diamonds with steeper pavilion angles. Is this correct?

I've also heard that, as long as the obstruction around the arrows is a fairly small circle and symmetrical, then it doesn't really make much of a difference in the appearance. It only becomes and issue when the obstructed area is fairly large (covering more than about 1/3 of the table) and/or if the obstruction circle is not symmetrical (meaning it blobs out in certain areas). Thoughts on this?

 

[John P]

Thanks @John Pollard, another informative post as always. Good to know the differences between the computer-generated ASETs and actual ASET images.

You’re welcome, and thank you for the thoughtful dialogue.

Regarding the obstruction surrounding the arrows, I've read that, in addition to a steeper pavilion angle above 40.8, the length of the star facets also contributes to this obstruction around the arrows. It's outlined in this article in the 5th bullet point:
http://www.heartsandarrows.com/hearts-arrows-diamond-ideal-cut-dna.aspx
Basically, steeper pavilion angles of >40.8, combined with longer star lengths >50%, can create white reflections that alter the appearance of the arrow pattern. This is why it's best to stick with star lengths around 50% or lower, particularly in diamonds with steeper pavilion angles. Is this correct?

Yes and no. It all depends on the goal. If “Hearts & Arrows” patterns or H&A photos are the goal then yes. But reducing star length simply to serve that goal brings more low-angle draw to the star facet junctions (see the ASET sims below) which may or may not be in-line with performance goals.



So your stars comment is correct if “Hearts & Arrows” marketing is the primary goal. But the H&A viewer is a symmetry-only tool. White light enters from the top. Colored light enters from the sides. It’s a contrast enhancer but does not show light return quality. And while ASET gives information about light return quality it only shows static brightness, contrast and leakage. They’re both useful tools but they tease out different info, and in both cases the info has limitations.

Relative to our goals we realize many people, including our dealers, refer to our diamonds as “H&A” but that’s not a goal you’ll hear in our offices. Those goals involve boosting visible fire and scintillation quality, which is a function of how all 57 facets on the diamond engage with each other. The tech viewers are great resources we support and employ, but we don't chase those views specifically.

I've also heard that, as long as the obstruction around the arrows is a fairly small circle and symmetrical, then it doesn't really make much of a difference in the appearance. It only becomes an issue when the obstructed area is fairly large (covering more than about 1/3 of the table) and/or if the obstruction circle is not symmetrical (meaning it blobs out in certain areas). Thoughts on this?

At 30 degrees of obstruction that's very true for standard round brilliants. Higher degrees of obstruction start bringing secondary and tertiary reflections into play. That’s ok in live ASET, IS, SS, FS (etc.) but computer modeling doesn’t always faithfully reproduce true micro-precision, which can result in blob-phantoms on relevant grading reports.

In the real world those table-reflection and obstruction dynamics are circumstance and viewer-dependent. When I look at a diamond at 25cm my bald head and shoulders cause less than 30 degrees obstruction. At 25cm my wife’s beautiful hair causes 30 degrees spot-on. But my aunt with huge blue Texas hair creates far more obstruction so she gets a completely different impression of brightness. Maybe that’s why she's always grumpy.

Making your question Pricescope-centric, you may have noticed the HCA approves some shallow combos which the major labs penalize. This is because obstruction in those combos increases notably as the viewer draws close. That said, they can still be bright and beautiful when the viewer is farther away, so the latest revision of HCA makes it clear those combos might better serve as earrings or pendants, rather than finger-blingers... Vive la difference.

 

[TreeScientist]

Yes and no. It all depends on the goal. If “Hearts & Arrows” patterns or H&A photos are the goal then yes. But reducing star length simply to serve that goal brings more low-angle draw to the star facet junctions (see the ASET sims below) which may or may not be in-line with performance goals.



So your stars comment is correct if “Hearts & Arrows” marketing is the primary goal. But the H&A viewer is a symmetry-only tool. White light enters from the top. Colored light enters from the sides. It’s a contrast enhancer but does not show light return quality. And while ASET gives information about light return quality it only shows static brightness, contrast and leakage. They’re both useful tools but they tease out different info, and in both cases the info has limitations.

Thanks for the detailed reply. Definitely helped to clarify a point that has always been confusing to me (the obstruction around the arrows on some ASETS).

Now, perhaps you could entertain a little thought experiment to help me understand the mind of a master cutter a little better pertaining to the choice of star and lower half lengths and the interaction between the upper and lower halves when cutting a diamond (probably one of the least understood topics on pricescope ).

Among the CBIs I've seen on your site, it seems that star %s generally range from 48-52% as the sweet spot (with some at 47 and 53%). So, in this thought experiment, lets say you have a diamond with a pavilion angle of 40.8% and lower halves of around 77%. In such a case, when would you choose to cut the stars on the shorter side (47-48%) vs on the longer side (52-53%)? Does it have something to do with the other aspects of the upper half (crown angle and table size)? Maybe the depth also plays a part (61% vs 62%)? Are there other aspects that come into play here outside of what is recorded in the diamonds average geometry? I'm just trying to understand how the choice is made to optimize the diamonds performance, as I've seen many CBIs that have star %s at or below 50% and thus little visible obstruction around the arrows in computerized ASETs and the H&A scope, and some with star %s above 50% and the presence of this blue ring in the ASET and white band around the arrows in the H&A scope.

Hope you can further enlighten us regarding the mystery of star % choice during cutting.

 

[Texas Leaguer]

On the topic of the face up computer generated ASET images on an AGS report, as John states the angle of obscuration used for printing is 33.5 degrees, rather than 30 in the structured ASET hemisphere.

The rationale as I understand it is this. The ray tracing algorithm analyzes the diamond at a variety of tilt angles, and also obscuration ranges. It looks at 30 and 40 degrees of obscuration and will penalize if the diamond has too much contrast at close viewing range (or big hair ). The algorithm combines the readings as two parts 30 and one part 40, hence the 33.5 range. Images made with this range also tend to give better arrows representation across the full range of AGS0 proportion combinations. The down side is that you will sometimes see more contrast around the center in the computer images printed on the report than you do in actual photos using the standard 30 degree construct.

 

[John P]

The down side is that you will sometimes see more contrast around the center in the computer images printed on the report than you do in actual photos using the standard 30 degree construct.

For internet sellers that may be true Bryan. However we experience a different down side entirely. Most Crafted by Infinity sales are made in jewelry showrooms. Logically, there are no such photos. Our diamonds are shown through several prescribed lighting conditions, then in color cards, and finally in optical-precision scope and ASET. Those are powerful views which never fail to elicit “wow!” or “cool!” or “holy (bleep)!” in live viewing. I love that part, as do our jewelers.

The down side? The AGS grading report presentation should be one of powerful correlation. But the occasional shopper asks why the report’s imprint shows a red center (when the actual diamond shows a green center in ASET) …or different obscuration effects (when the actual diamond shows less) …or the occasional blob-phantom (when the actual diamond shows none). Per your algorithm post it can be explained, but in the moment it’s not a confidence builder. For now I'm dutifully teaching our showroom jewelers why shoppers might see differences between their diamond in the ‘official’ AGS ASET viewer - versus what's printed on their diamond’s ‘official’ AGS report.

For the record, the folks at AGSL have been responsive, accessible and proactive in hearing and helping us with this concern in specific cases.

 

[John P]

Thanks for the detailed reply. Definitely helped to clarify a point that has always been confusing to me (the obstruction around the arrows on some ASETS).

Now, perhaps you could entertain a little thought experiment to help me understand the mind of a master cutter a little better pertaining to the choice of star and lower half lengths and the interaction between the upper and lower halves when cutting a diamond (probably one of the least understood topics on pricescope ).

Among the CBIs I've seen on your site, it seems that star %s generally range from 48-52% as the sweet spot (with some at 47 and 53%). So, in this thought experiment, lets say you have a diamond with a pavilion angle of 40.8% and lower halves of around 77%. In such a case, when would you choose to cut the stars on the shorter side (47-48%) vs on the longer side (52-53%)? Does it have something to do with the other aspects of the upper half (crown angle and table size)? Maybe the depth also plays a part (61% vs 62%)? Are there other aspects that come into play here outside of what is recorded in the diamonds average geometry? I'm just trying to understand how the choice is made to optimize the diamonds performance, as I've seen many CBIs that have star %s at or below 50% and thus little visible obstruction around the arrows in computerized ASETs and the H&A scope, and some with star %s above 50% and the presence of this blue ring in the ASET and white band around the arrows in the H&A scope.

The answers you seek may require a paradigm shift on your part regarding diamond cutting. Remember, this is not cookie dough. It’s not wood. It’s not even granite. It’s pure, unyielding adamantine willpower. Diamond resists. Diamond fights. And though it’s ten times harder than corundum (!) it grows so that each individual crystal has harder and softer places. Depending on growth directions and graining, that facet you planned may not run in a certain direction at all. It will scorch. It will burn. It will vex you and drive you mad.

If you learn this about diamonds it will open your mind to greater understanding. Blocking machines and assembly lines work facets into shape, but they don’t refine the material. Achieving refinement and, beyond that, achieving consistent optical results requires purer starting material, considerably more time in assessment and planning, greater expense in tools and labor and a willingness to polish away more weight as we undertake fine-tuning.

when would you choose to cut the stars on the shorter side (47-48%) vs on the longer side (52-53%)?

Per the above, “choose” is a function of the overall dance with the diamond. It’s a game. Like a chess match.

Does it have something to do with the other aspects of the upper half (crown angle and table size)? Maybe the depth also plays a part (61% vs 62%)?

Yes and yes. Table, crown, stars and upper halves require certain harmony in our process and, as you intuit, must communicate perfectly with the pavilion. So we’re not focused on depth, as such. It will be what it will be, as a by-product of making the proper moves in the dance.

Are there other aspects that come into play here outside of what is recorded in the diamonds average geometry?

Absolutely. What did the sawable crystal provide as a basis? Where is that gletz we must accommodate while faithfully achieving our optical goals? Will said gletz or pique or graining necessitate a slightly steeper X, requiring us to massage Y in order to collectively focus the facet groups? Was one facet more stubborn than we assessed, requiring equal and opposite adjustments to the collective group as we execute the dance?

? I'm just trying to understand how the choice is made to optimize the diamonds performance, as I've seen many CBIs that have star %s at or below 50% and thus little visible obstruction around the arrows in computerized ASETs and the H&A scope, and some with star %s above 50% and the presence of this blue ring in the ASET and white band around the arrows in the H&A scope.

I fully realize that this forum tends to focus people on 2D photos. They are definitely useful, in general sense. But extracting a single micro-nuance, or a single facet group’s number, is like trying to assess how the dancer will move based on a still photo, or based on height and weight.

And I don’t mean to bake your noodle further, but did you already realize there’s not usually any information provided about the upper-half facets? Facets which are key to dispersive character and contrast elements. Facets which were key to the Eightstar diamond movement and remain crucial in well-cut diamonds to overall performance character. They make up nearly 1/3 of the facets on the diamond. Yet no one talks about them.

Hope you can further enlighten us regarding the mystery of star % choice during cutting.

In this 'thought experiment' you've posed I especially like that you asked about the star facets. Why? Because the stars are traditionally ‘clean-up’ facets. True, that’s with regard to assembly line cutting. But even productions attempting for “H&A” patterns use them for that purpose. That is why I like your question. Hardly anyone gives thought to this group, and yet we prescribe their length and consistency very deliberately, based on making the proper dance moves with the other facet groups.

In summary: Our proportions bullseye may well be the industry’s tightest but no single data point tells the story. You can break down the stats of an NFL quarterback or running-back as much as you wish, but regardless of solo numbers the team’s achievements are based on how all of the talent works together. It’s the same concept here.

 

[TreeScientist]

The answers you seek may require a paradigm shift on your part regarding diamond cutting. Remember, this is not cookie dough. It’s not wood. It’s not even granite. It’s pure, unyielding adamantine willpower. Diamond resists. Diamond fights. And though it’s ten times harder than corundum (!) it grows so that each individual crystal has harder and softer places. Depending on growth directions and graining, that facet you planned may not run in a certain direction at all. It will scorch. It will burn. It will vex you and drive you mad.

If you learn this about diamonds it will open your mind to greater understanding. Blocking machines and assembly lines work facets into shape, but they don’t refine the material. Achieving refinement and, beyond that, achieving consistent optical results requires purer starting material, considerably more time in assessment and planning, greater expense in tools and labor and a willingness to polish away more weight as we undertake fine-tuning.


Per the above, “choose” is a function of the overall dance with the diamond. It’s a game. Like a chess match.


Yes and yes. Table, crown, stars and upper halves require certain harmony in our process and, as you intuit, must communicate perfectly with the pavilion. So we’re not focused on depth, as such. It will be what it will be, as a by-product of making the proper moves in the dance.


Absolutely. What did the sawable crystal provide as a basis? Where is that gletz we must accommodate while faithfully achieving our optical goals? Will said gletz or pique or graining necessitate a slightly steeper X, requiring us to massage Y in order to collectively focus the facet groups? Was one facet more stubborn than we assessed, requiring equal and opposite adjustments to the collective group as we execute the dance?


I fully realize that this forum tends to focus people on 2D photos. They are definitely useful, in general sense. But extracting a single micro-nuance, or a single facet group’s number, is like trying to assess how the dancer will move based on a still photo, or based on height and weight.

And I don’t mean to bake your noodle further, but did you already realize there’s not usually any information provided about the upper-half facets? Facets which are key to dispersive character and contrast elements. Facets which were key to the Eightstar diamond movement and remain crucial in well-cut diamonds to overall performance character. They make up nearly 1/3 of the facets on the diamond. Yet no one talks about them.


In this 'thought experiment' you've posed I especially like that you asked about the star facets. Why? Because the stars are traditionally ‘clean-up’ facets. True, that’s with regard to assembly line cutting. But even productions attempting for “H&A” patterns use them for that purpose. That is why I like your question. Hardly anyone gives thought to this group, and yet we prescribe their length and consistency very deliberately, based on making the proper dance moves with the other facet groups.

In summary: Our proportions bullseye may well be the industry’s tightest but no single data point tells the story. You can break down the stats of an NFL quarterback or running-back as much as you wish, but regardless of solo numbers the team’s achievements are based on how all of the talent works together. It’s the same concept here.

Once again, thank you for taking the time to write out a detailed, illuminating response to my question. As a scientist myself, I appreciate the attention to detail and quest for perfection that is at the heart of your cutting house. While I will (likely) never be a diamond cutter myself, I can see some analogies between cutting a perfect diamond and the work that we do in our lab, which is why I've particularly enjoyed learn more on this forum.

More specifically, our lab is a isotope dendroclimatology lab, meaning that we look at variations in stable isotope ratios across tree rings and use these variations to reconstruct past climates, from thousands to millions of years ago. One of the techniques that our lab specializes in is within-ring isotope analysis, meaning that we look at how the isotope ratios change within single tree rings to determine the extent of seasonality (meaning the difference between summer and winter temperatures) within individual years. The reason why our lab has been at the forefront of these seasonality reconstructions, and why most other labs cannot get anywhere close to the level of data precision that our lab consistently puts out, lies in our technique.

To understand this further, it bears mentioning that only the outermost portion of a tree is actually "alive" meaning synthesizing new tissue. As a tree grows older, it lays down new tissue parallel to the center of the tree, while the tissue directly behind this tissue dies off. Thus, each parallel segment in a tree ring represents a "snapshot" of the conditions under which that material was formed. To get an idea of how the stable isotope ratios, and thus the climate that the tree was growing under, changes over the course of a year, we take extremely fine slices of a tree core parallel to the direction of growth. Analyzing each of these slices individually, and then looking at the relative differences in isotope ratios (highest value to lowest value) gives us the ratio of highest to lowest temperature or precipitation (depending on the isotope) in a given year.

Seems easy right? Well, many other labs seem to think so, because they've tried this same method on their own samples. And while it generally works OK for them, their reconstructions are hardly ever as clean as ours. This is because they do their slicing with a microtome, which takes perfectly parallel slices of any object that you line up to the blade. However, tree rings are NEVER perfectly parallel, as slight variations in growth rate throughout a trunk and the curve of the tree around the center (since trees are cylinders after all) means that the rings are usually tilted a bit in the Y and/or Z axis.

For example, take a look at the picture below. The rings in this core are actually EXTREMELY straight as far as tree rings are concerned. Some of the best we've worked on. But even in this sample, you can see slight variations in the curve of the darkwood bands in these trees, indicating that the growth plane was not perfectly parallel.



So if you're using a machine that takes perfectly parallel slices, you're not actually getting a perfect snapshot of a single point in time of the trees life, but rather a mixture of points in time depending on the tilt of the growth plane. In our lab, we take each slice by hand under a 25X microscope using a safety razor, rotating each core 10 to 20 times per slice to make sure that we're following every little variation in the growth plane. Does this take significantly longer than using an automated microtome? You bet your ass it does. But our results speak for themselves. We've tried the microtome before, and the results we get simply don't meet the level of perfection that we strive for.

Well, this thread has gone off in a direction that I'm sure the OP never envisioned it going (sorry OP ). But coming back to the diamond cutting, I just wanted to give this example to show that, yes, I am able to appreciate the level of detail that you strive for in crafting CBIs. And I totally agree with you that the level of precision when cutting any 3-dimensional object cannot be adequately portrayed in 2-dimensional charts or images. If this was the case, using a microtome would be just as effective for cutting tree ring cross sections, just like cutting a diamond to meet the minimum depth%, table%, crown and pavilion angles required to attain GIA excellent would result in a diamond as beautiful as a CBI.

So, from a cutter of trees to a cutter of diamonds, thanks for giving me a glimpse into your mindset while you go about your craft.

 

[John P]

@TreeScientist , it's Sunday family time but I saw your reply and wanted to quickly express what a great read it is. It's clear you understand confounders, systemic realities in both of our situations. It's precisely why quality, consistency and achievement are - as you said - all in the technique.

More later. For now, thank you for the stimulating read!

 

[cflutist]

Looks like our OP bought HPD9819

 

[Aimyr]

Looks like our OP bought HPD9819

Indeed I did! It was unfortunately the only one of the 4 my jeweler could get their hands on and was in Antwerpen, the others were reserved for the American market. Not sure what was up with that but considering they opened up a trade account with CBI specifically on my request (which took multiple weeks/months) I´m not going to be too picky neither (not that I have personal preferences anyways so any would do). If you look at my post history you´ll find a long thread with info about my journey when I bought their subpar inhouse diamond so I was lucky (or persuasive enough) to convince them to do business with Infinity Diamonds directly. It didn´t even end up being that much more expensive!! :O F-VS1 in-house to this CBI E-VS1 was only a $250 increase! Considering the in-house diamond was fairly overpriced I figured I´ve gotten some value back although it´s still somewhat too expensive but at least I also had the benefits of dealing with my jeweler face to face. They were super accommodating and patient in the process.

I´m gonna drop them a line tomorrow and tell them to make sure to set the diamond symmetrically in relation to the prongs and then I should have everything in a couple of weeks Yaay!

@TreeScientist Don´t worry about the technical stuff, I love reading about it!