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"Precision cut" - what does this mean?

yssie

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If I can ramble a bit..


Let's take ACA RBs. WF lists the requirements here - tight ranges to which all facets/proportions must conform:
Depth 59.5-62%, Table 53-58%, Girdle T-M-SlThk, Culet N-P-S, Pol/Sym Id/Id, Crown 34-35d, Pav 40.6-40.9d, Star 48-55%, LGF 76-80%, radial optical symmetry.
So, they chose a template and ran with it. Obviously this results in stones that look very similar in still photos and that manipulate light similarly, but apparent light return "type" can be quite different based on stone (facet) size - so a 0.5ct ACA and a 2.5ct ACA actually perform visibly differently.

Then there's the Octavia. From my understanding - Karl, please correct me if I'm wrong - Karl chose a certain Look and Feel, and considers it important to keep both patterning and performance "type" comparable - so he's chosen a certain performance type 'ideal', and all stones - all sizes, all colours - are designed to regress to the mean. So design is tweaked based on stone size/colour? I definitely have always thought of Octavias as "precision cut" - just apparently in a different way from the WF template model. How important to the Octavia brand name is optical symmetry (radial, or across some static axis)?

Another shape I've always considered to be precision cut is GOG's AVC - and these seem to have an entirely different model! There are fat and skinny large and small D/E/Fs, fat and skinny large and small Ms and lower, and so we've got differences in light return thanks to different sizes, different patterns of longer/fatter, different colours... no design patterns in faceting+colour+size that I can make out, at least. What are the reasons for choosing a given design - is it based solely on shape of the rough? And the same question - must all AVCs have a clear and precise axis of symmetry?

PSer Lula has commented that all the Infinity RBs she's seen have had the same characteristic look about them - and she's owned an M and an I, which are quite different in body colour. I know another PSer Bright Ice has an Infinity O and a pair of smaller Ns. What is the Infinity model? Certainly big/small, D-O/P all look the same in photos...
Can I ask what sorts of modifications are common for more strongly coloured material to account for the wrench that is whatever absorption spectra - to yield "similar" light return across such a variety of colours? I understand if this would be too much info to share here, though of course I would love to learn more.

And what about DBL's new line of antique yellow cushions, in which those same concerns about material colour are only highlighted?

JA's True Hearts and GOG's Superior RB inventories confuse me on this front. Some of the True Hearts stones I would label "precision cut" in my head, some I wouldn't. I would call all the GOG Superior stones "precision cut". I don't know if JA & GOG have these stones specially cut, or if they're sourced from larger inventories en masse and the finds w/ H&A patterns are labelled afterward.. to make the lines stones must have high optical symmetry and proportions that yield some sort of clear hearts and arrows pattern, what exactly that pattern is - how thick the Vs are, say - doesn't matter, so obviously various stones of various sizes can have very different looks and 'types' of light return.


I guess.. my question: In the end the words "precision cut diamond" do NOT indicate to me that
1. There is a repeating facet patterning that is consistent across a brand
2. There is a repeating light return "type" that is consistent across a brand
3. The vendor specified either (1) or (2) to the cutter

So, would it be safe to say that the term "precision cut" indicates a certain high optical symmetry? Or is it more of a generic measure of how closely the results of a cutting job represent whatever ideal was chosen (and so doesn't mean very much at all until we know what that ideal is)... or something else?
 

NARRISHKEIT

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Others have asked the same questions in the past and received limited responses. The brands mentioned won't likely divulge their criteria or secrets above and beyond a sales and marketing pitch but lets hope for the best.

Here are my thoughts and opinions based on some observations and reading PS archives:

1) WF ACA, are not specifically cut for them but rather they pool from their cutters and select inventory for ACA line upon evaluation.
Some criteria is obvious (like near Tolk) other criteria is "secret" and the entire process is not transparent. They judge by optical tests and have limited tolerances for deviations seen in heart and arrows images as well as ASET but it seems the range is narrowed by quantitative and qualitative criteria. They will not disclose all criteria.

2) Can't speak much about Octavia but it has an optical signature that is required with strong return of overhead light to the viwerfrom edge to edge (predominantly ASET Red). The design seems to have changed as the tapering of the corners is significantly different from one example to another.

3) GOG AVCs must have an particular optical signature within the 8 main vintage cushion brilliant style. This does not mean a particular LW ratio or precision among facets has to be exact like in a round but angles must be adjusted to be complimentary and to maintain a particular optical signature.

The 4 larger mains on the pavilion must strongly reflect overhead light (ASET red) and the stones must have excellent light return of high angle light from edge to edge(predominantly ASET red). LW ratio is not a constraint and as long as the optical signature is respected there are some deviations amongst them and even amongst the different cutting factories that have produced them.

4) DBL antique cushions appear to be pulled from generic inventory from New York. Particular ones in the vintage 8 main antique style that can be purchased at a relatively low pricepoint (price/carat) as compared to other fancy and colorless vintage faceted diamonds.

These generic yellow antique brilliants are generally from cheaper paler yellow rough. For example rough that produces a finished diamond that was graded light yellow YZ, with strong blue fluoro and SI2 clarity. Proportions and precision appear to be strongly influenced by weight retention (cheap price/carat) and maintaining as much color as possible from the lightly saturated rough. Facet precision and a light return signature is not consistent by any means.
 

Rockdiamond

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What a perceptive, thought provoking discussion yssie!
You raise so many good points.

First thing that comes to mind is the word "Brand"- what does it mean?
You've listed the very narrow specs one brand lists. What if someone was to cut a diamond that fit those specs...would it be identical to the "branded" stone?
I think the answer is obvious, from a physical standpoint- but I think that when we speak of "branded" diamonds, I believe that diamond sellers brand an entire service- as opposed to a particular style of diamond per se.

I asked Yoram F- who cuts our branded stones- among others- if we should send the stones to AGSL to get an "ideal" cut grade- as some others have done.
He informed me that we would not get the same grade- as his goals were different cutting our stones, as compared to the others.
OK- so what does an "ideal" cushion have that others don't?
That leads to a question of calibration.
One new branded stone has claimed that it's "20% brighter" than others.
How is this measured?

That leads to the term "performance"
Does store A's diamond perform "better" than store b's?
How can we prove this?

Which brings me back to my initial point. In diamonds, a brand is more about the seller than the particualrs of the diamond IMO

We can document how well a seller has performed far better than we can measure "light performance"

ETA- NAKARASHET is again throwing around inaccurate "misinformation"- as I mentioned, our branded stones are cut by Yoram F. There's nothing "Random" about his designs
 

Rockdiamond

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NARRISHKEIT|1313167325|2989394 said:
Others have asked the same questions in the past and received limited responses. The brands mentioned won't likely divulge their criteria or secrets above and beyond a sales and marketing pitch but lets hope for the best.

Here are my thoughts and opinions based on some observations and reading PS archives:

1) WF ACA, are not specifically cut for them but rather they pool from their cutters and select inventory for ACA line upon evaluation.
Some criteria is obvious (like near Tolk) other criteria is "secret" and the entire process is not transparent. They judge by optical tests and have limited tolerances for deviations seen in heart and arrows images as well as ASET but it seems the range is narrowed by quantitative and qualitative criteria. They will not disclose all criteria.

2) Can't speak much about Octavia but it has an optical signature that is required with strong return of overhead light to the viwerfrom edge to edge (predominantly ASET Red). The design seems to have changed as the tapering of the corners is significantly different from one example to another.

3) GOG AVCs must have an particular optical signature within the 8 main vintage cushion brilliant style. This does not mean a particular LW ratio or precision among facets has to be exact like in a round but angles must be adjusted to be complimentary and to maintain a particular optical signature.

The 4 larger mains on the pavilion must strongly reflect overhead light (ASET red) and the stones must have excellent light return of high angle light from edge to edge(predominantly ASET red). LW ratio is not a constraint and as long as the optical signature is respected there are some deviations amongst them and even amongst the different cutting factories that have produced them.

4) DBL antique cushions appear to be pulled from generic inventory from New York. Particular ones in the vintage 8 main antique style that can be purchased at a relatively low pricepoint (price/carat) as compared to other fancy and colorless vintage faceted diamonds.

These generic yellow antique brilliants are generally from cheaper paler yellow rough. For example rough that produces a finished diamond that was graded light yellow YZ, with strong blue fluoro and SI2 clarity. Proportions and precision appear to be strongly influenced by weight retention (cheap price/carat) and maintaining as much color as possible from the lightly saturated rough. Facet precision and a light return signature is not consistent by any means.
Can you please show us others?

I know that I've tried to find Old Mine Brilliant stones in Y-Z colors for years- they're not out there.
One reason we teamed up with Yoram on this.

But I'd love to see all these low priced ones you speak of.
The second facet structure Yoram designed for us specifically is based on the "Tiffany Yellow" we call it a double decker cushion.
Nothing "generic" about these.
I will certainly mention to Diagem ( Yoram) that you feel he's cutting for weight retention at the cost of beauty- maybe you should give him some pointers

Thank you NARRISHKEIT for raising these issues.
 

kenny

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I think we need to differentiate between two things:

1. The cut recipe
2. How well the cutter followed the recipe


BTW "precision cut" from a businessperson's point of view could also be getting the heaviest stone possible from a piece of rough.
 

Rockdiamond

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THANK YOU Kenny!!

The best "performing" stone could be the one which is the most profitable one to sell.

The terms like "performance" and "superior optics" get thrown around and somehow switch from "advertisement" to "education" in a way that I find frightening- because it's misleading to people
 

Lula

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kenny|1313169913|2989424 said:
I think we need to differentiate between two things:

1. The cut recipe
2. How well the cutter followed the recipe


BTW "precision cut" from a businessperson's point of view could also be getting the heaviest stone possible from a piece of rough.
Good points, Kenny.

Great topic for a thread, yssie. I do think "precision cut" needs further definition, and we may be talking about different things when we use that term.

By my definition, precision cutting goes way beyond simple "light performance" measures. In my view, precision cutting is both an art and a science, and I believe the cutter's vision, and how well that vision is executed (which ties in to cut consistency) cannot be ignored.

There are some old threads on using Sarin-Helium-Ogi data to assess cut precision. There are also some old threads that discuss the difference between optical symmetry, lab symmetry, meet point symmetry, etc. A word about "mathematical precision": In the case of modern RB's, mathematical precision may lead to a precisely-cut stone, but I do not believe that mathematical precision alone makes a beautiful stone -- and that's where the cutter's "vision" or artistic ability comes into play. I believe you need both to achieve cut precision (the way I define it).

A stone can be precisely cut to any standard; the question becomes whether or not we view that "standard" as beautiful with our own eyes.
 

Rockdiamond

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Lula|1313173065|2989461 said:
kenny|1313169913|2989424 said:
I think we need to differentiate between two things:

1. The cut recipe
2. How well the cutter followed the recipe


BTW "precision cut" from a businessperson's point of view could also be getting the heaviest stone possible from a piece of rough.
Good points, Kenny.

Great topic for a thread, yssie. I do think "precision cut" needs further definition, and we may be talking about different things when we use that term.

By my definition, precision cutting goes way beyond simple "light performance" measures. In my view, precision cutting is both an art and a science, and I believe the cutter's vision, and how well that vision is executed (which ties in to cut consistency) cannot be ignored.

There are some old threads on using Sarin-Helium-Ogi data to assess cut precision. There are also some old threads that discuss the difference between optical symmetry, lab symmetry, meet point symmetry, etc. A word about "mathematical precision": In the case of modern RB's, mathematical precision may lead to a precisely-cut stone, but I do not believe that mathematical precision alone makes a beautiful stone -- and that's where the cutter's "vision" or artistic ability comes into play. I believe you need both to achieve cut precision (the way I define it).

A stone can be precisely cut to any standard; the question becomes whether or not we view that "standard" as beautiful with our own eyes.
Lula,- you've used the term "simple light performance measures"- which I think goes directly to the subject at hand.
What are simple light performance measures?
I don't believe there's any meaningful measurement of "light performance"- however sellers are using this term as though there's some definitive measurement.
Again- advertisement somehow transmoglifies into fact.
I just made up that word by the way- transmoglifies.

Hey, other people can make up words like "light performance" :twirl:
 

Lula

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Rockdiamond|1313176262|2989526 said:
Lula|1313173065|2989461 said:
kenny|1313169913|2989424 said:
I think we need to differentiate between two things:

1. The cut recipe
2. How well the cutter followed the recipe


BTW "precision cut" from a businessperson's point of view could also be getting the heaviest stone possible from a piece of rough.
Good points, Kenny.

Great topic for a thread, yssie. I do think "precision cut" needs further definition, and we may be talking about different things when we use that term.

By my definition, precision cutting goes way beyond simple "light performance" measures. In my view, precision cutting is both an art and a science, and I believe the cutter's vision, and how well that vision is executed (which ties in to cut consistency) cannot be ignored.

There are some old threads on using Sarin-Helium-Ogi data to assess cut precision. There are also some old threads that discuss the difference between optical symmetry, lab symmetry, meet point symmetry, etc. A word about "mathematical precision": In the case of modern RB's, mathematical precision may lead to a precisely-cut stone, but I do not believe that mathematical precision alone makes a beautiful stone -- and that's where the cutter's "vision" or artistic ability comes into play. I believe you need both to achieve cut precision (the way I define it).

A stone can be precisely cut to any standard; the question becomes whether or not we view that "standard" as beautiful with our own eyes.
Lula,- you've used the term "simple light performance measures"- which I think goes directly to the subject at hand.
What are simple light performance measures?
I don't believe there's any meaningful measurement of "light performance"- however sellers are using this term as though there's some definitive measurement.
Again- advertisement somehow transmoglifies into fact.
I just made up that word by the way- transmoglifies.

Hey, other people can make up words like "light performance" :twirl:
RD, read the rest of my post! Hellloooooooo - I'm agreeing with you! That's why I put "light performance" in quotes and used the word "simple." I believe we rely on Ideascope images, and other tools that purport to measure light return, far too much on PS. I believe savvy dealers have learned how to manipulate these images to the consumers' disadvantage, and that, just like there are stones cut to preserve weight, I suspect there are now stones being cut to "pass" the H&A standards and Idealscope standards that may, in real life, be dogs.

ETA: But, please, let's not derail the very interesting thread that yssie started with talk of light performance. This thread goes way beyond that, into areas that I believe you have a wealth of information that would add much to the discussion, i.e., is "cut precision" -- however you define it -- a factor in fancy cut or colored diamonds?
 

Lula

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Rockdiamond|1313168737|2989410 said:
What a perceptive, thought provoking discussion yssie!
You raise so many good points.

First thing that comes to mind is the word "Brand"- what does it mean?
You've listed the very narrow specs one brand lists. What if someone was to cut a diamond that fit those specs...would it be identical to the "branded" stone?
I think the answer is obvious, from a physical standpoint- but I think that when we speak of "branded" diamonds, I believe that diamond sellers brand an entire service- as opposed to a particular style of diamond per se.

I asked Yoram F- who cuts our branded stones- among others- if we should send the stones to AGSL to get an "ideal" cut grade- as some others have done.
He informed me that we would not get the same grade- as his goals were different cutting our stones, as compared to the others.
OK- so what does an "ideal" cushion have that others don't?
That leads to a question of calibration.
One new branded stone has claimed that it's "20% brighter" than others.
How is this measured?

That leads to the term "performance"
Does store A's diamond perform "better" than store b's?
How can we prove this?

Which brings me back to my initial point. In diamonds, a brand is more about the seller than the particualrs of the diamond IMO

We can document how well a seller has performed far better than we can measure "light performance"

ETA- NAKARASHET is again throwing around inaccurate "misinformation"- as I mentioned, our branded stones are cut by Yoram F. There's nothing "Random" about his designs[/quote]

RD, the parts of your thread that I bolded, I believe, go directly to the "art" portion of cut precision (as I define cut precision, i.e., that it's an art and a science). But for Yoram to achieve the look he wants in the stone (the aesthetic or artistic component) he must have mastery over the science portion of cutting, which include understanding the physics of light return, and, perhaps more important, the individual characteristics of the particular piece of rough he is cutting. Only the cutter can tell you if the finished product matches his artistic vision for the stone. But I, as a consumer, can see, by looking at a number of stones from a particular brand, how well that vision translates across the brand. If the stones do not have a consistent look to them (again, beyond what we can see on an IS or ASET), then I am choosing to buy a branded stone for reasons other than cut consistency (i.e., the Tiffany blue box; service and return policies, etc.).
 

NARRISHKEIT

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Precision
n.
The state or quality of being precise; exactness.
The ability of a measurement to be consistently reproduced.
The number of significant digits to which a value has been reliably measured.
adj.
Used or intended for accurate or exact measurement: a precision tool.
Made so as to vary minimally from a set standard: precision components.
Of or characterized by accurate action: precision bombing.

I have always considered the definition as it applies to diamonds to be consistant reproduceability. For example the mains in a round brilliant have good precision if the pavilion main angles are 40.8 40.7 40.8 40.8 40.8 40.8 40.7 40.8.

Or precision in a brand being the same virtual facet pattern or optical signature from one stone to the next.

Yssie and others are you using another definition?
 

Rockdiamond

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SOOOOO Sorry I missed your point Lula!!

Glad to know we agree!

The concept of "light performance" should not derail this very interesting conversation- as long as we have "debunked" the term.

More on my point earlier- about what a "branded diamond" is.

After having spent so many years dealing with consumers, it seems to me that the service offered by the seller is inseparable from the quality of the stone, or cut.
That is to say- brands that are being discussed here DO offer something unique.
But how much of that is a given facet pattern- or the cutter's ability to achieve this pattern consistently- and how much are things like buy back or trade up policies, specially designed jewelry, customer service, straightforward information, quality website- or posh store etc

I love to use cars as analogy.
Jeep came out with a popular model, which is copied by Lexus ( for example).
There's a lot of commonality, but there's specific differences which are easily visible to the customer.
If Lexus copied the jeep to the point you could not tell them apart, they'd get their butts sued- and they'd loose.

When it comes to the design of a diamond, it's a totally different story.
If a cutter wanted to recreate any of these branded cuts, there's virtually NO legal remedy for the cut's inventor.
For one thing, you could change small details that have almost no bearing on the appearance, yet make the design different enough that you did not infringe on a patent.
Henry Grossbard learned this- the hard way. He invented the radiant cut, and spent years- and hundreds of thousands of dollars protecting it.
He actually won- but the financial settlement paid his legal bills- nothing more.
The case proved that you can't defend a facet design.
After all was said and done, he realized his design was now "open source"

Yoram is ( IMO) a genius of diamond cutting- but I don't believe he can protect his amazing designs in the courts. If another cutter had the skill and correct rough to copy an Octavia, it would be nearly impossible for Yoram to stop them. Unless they were stupid enough to use the same name......

I might be wrong- but I believe his strategy is selecting the sellers carefully.
Again, the seller offering the brand adds a large percentage of the value- both to the cutter, and the consumer.
It also makes sense to pick a design that's hard to find on the market- clearly the cushion provides greater opportunity for creative design. And it's harder to find them on the market, as compared to rounds. That makes less competition simply due to availability.

For us, part of the key was to find a product that dovetailed with our strengths- Yoram has proved to be shrewd in this department- he's developed particular cuts that fit with different seller's strategies.

Now if we can only get him to cut Octavias in color :love:
 

Rockdiamond

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NARRISHKEIT|1313179541|2989576 said:
Precision
n.
The state or quality of being precise; exactness.
The ability of a measurement to be consistently reproduced.
The number of significant digits to which a value has been reliably measured.
adj.
Used or intended for accurate or exact measurement: a precision tool.
Made so as to vary minimally from a set standard: precision components.
Of or characterized by accurate action: precision bombing.

I have always considered the definition as it applies to diamonds to be consistant reproduceability. For example the mains in a round brilliant have good precision if the pavilion main angles are 40.8 40.7 40.8 40.8 40.8 40.8 40.7 40.8.

Or precision in a brand being the same virtual facet pattern or optical signature from one stone to the next.

Yssie and others are you using another definition?
I realize you'll probably continue to ignore me, but what is an "optical signature"?
 

Rockdiamond

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Lula|1313179243|2989568 said:
Rockdiamond|1313168737|2989410 said:
What a perceptive, thought provoking discussion yssie!
You raise so many good points.

First thing that comes to mind is the word "Brand"- what does it mean?
You've listed the very narrow specs one brand lists. What if someone was to cut a diamond that fit those specs...would it be identical to the "branded" stone?
I think the answer is obvious, from a physical standpoint- but I think that when we speak of "branded" diamonds, I believe that diamond sellers brand an entire service- as opposed to a particular style of diamond per se.

I asked Yoram F- who cuts our branded stones- among others- if we should send the stones to AGSL to get an "ideal" cut grade- as some others have done.
He informed me that we would not get the same grade- as his goals were different cutting our stones, as compared to the others.
OK- so what does an "ideal" cushion have that others don't?
That leads to a question of calibration.
One new branded stone has claimed that it's "20% brighter" than others.
How is this measured?

That leads to the term "performance"
Does store A's diamond perform "better" than store b's?
How can we prove this?

Which brings me back to my initial point. In diamonds, a brand is more about the seller than the particualrs of the diamond IMO

We can document how well a seller has performed far better than we can measure "light performance"

ETA- NAKARASHET is again throwing around inaccurate "misinformation"- as I mentioned, our branded stones are cut by Yoram F. There's nothing "Random" about his designs[/quote]

RD, the parts of your thread that I bolded, I believe, go directly to the "art" portion of cut precision (as I define cut precision, i.e., that it's an art and a science). But for Yoram to achieve the look he wants in the stone (the aesthetic or artistic component) he must have mastery over the science portion of cutting, which include understanding the physics of light return, and, perhaps more important, the individual characteristics of the particular piece of rough he is cutting. Only the cutter can tell you if the finished product matches his artistic vision for the stone. But I, as a consumer, can see, by looking at a number of stones from a particular brand, how well that vision translates across the brand. If the stones do not have a consistent look to them (again, beyond what we can see on an IS or ASET), then I am choosing to buy a branded stone for reasons other than cut consistency (i.e., the Tiffany blue box; service and return policies, etc.).
Great points Lula.
It's a combination- first, the cutter needs to have the skill, knowledge and equipment - the cutter needs an overwhelming command of the tools.
But the underlined part is incredibly perceptive of you.
We should compare a diamond cutter to an architect.
In a sense, round brilliant is like tract housing- make them all look the same. With real estate, you can simply bulldoze the land flat, so you can make your identical houses.
With diamonds, you need to cut the stone based on the rough.
Many round diamonds come from octehedrons. A good percentage are sewn, resulting in a larger and smaller peice, each polished into a round .

"Crystals" are generally cut into princess cuts, emerald cuts, and radiant cuts.
Hopefully Yoram will chirp in- I'm not sure what type of rough OMB's are cut from.
But none of these rules is hard and fast- sometimes rounds are cut from other types of rough


Fancy Shapes present the opportunity for a far more "artistic" expression , from the cutter.
Some rough, like "makel" may be more straightforward ( it's easier to visualize the shape , from the rough)- they become pear shapes and heart shapes.

But other cases, the cutter (architect of the diamond) must visualize something totally different in his head.
Once it's done, others can , and will, copy.
But even then, a big part of a cutter's success is how good they are at figuring out how to use that particular rough
 

Regular Guy

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when no one is looking, moving very fast to go in front of the next person in line at the grocery...

:))
 

NARRISHKEIT

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rockdiamond said:
I know that I've tried to find Old Mine Brilliant stones in Y-Z colors for years- they're not out there.
One reason we teamed up with Yoram on this.
I have made some rather broad assumptions based on this particular stone (the only one currently available) and others already sold from your site which I would welcome you clarifying with straightforward answers. If my assumptions are wrong I welcome the correction or clarifcation.

Since you have identified Diagem (Yoram F) as the cutter this a perfect time to learn about his rough planning process for this stone, and his precise answers would be far superior to my rough guesses made by working backwards from the finished product.

This stone has beautiful large virtual facets and a pleasing outline shape but I am curious about a number of things:

1) Are the vintage faceted stones with the DBL girdle inscription cut by Yoram an after the fact selection of finished diamonds for your trademark or do you prepurchase rough?

2) Did you choose this particular rough or stone guessing how it would finish or was this chosen from vintage faceted stones already cut and submitted to GIA previously by Yoram?

3) Why was a finished stone graded color YZ, Strong Blue Fluoro, SI2 clarity and that just hit the 1 carat mark chosen for your DBL girdle inscription?

4) What were the primary reasons why this stone finished with a 78.1% depth with a Very Thick to Extremely Thick Girdle? (As these are unusual proportions even for a colored stone.)


OMBDBL.jpg OMBDBLPhotograph.jpg

To Answer Your Question:

Optical signature is a term describing a diamond's unique visual fingerprint. This fingerprint can be examined by considering the diamond's light return properties and virtual facet patterns.
 

diagem

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NARRISHKEIT|1313184412|2989643 said:
rockdiamond said:
I know that I've tried to find Old Mine Brilliant stones in Y-Z colors for years- they're not out there.
One reason we teamed up with Yoram on this.
I have made some rather broad assumptions based on this particular stone (the only one currently available) and others already sold from your site which I would welcome you clarifying with straightforward answers. If my assumptions are wrong I welcome the correction or clarifcation.

Since you have identified Diagem (Yoram F) as the cutter this a perfect time to learn about his rough planning process for this stone, and his precise answers would be far superior to my rough guesses made by working backwards from the finished product.

This is stone has beautiful large virtual facets and a pleasing outline shape but I am curious about a number of things:

1) Are the vintage faceted stones with the DBL girdle inscription cut by Yoram an after the fact selection of finished diamonds for your trademark or do you prepurchase rough?

2) Did you choose this particular rough or stone guessing how it would finish or was this chosen from vintage faceted stones already cut and submitted to GIA previously by Yoram?

3) Why was a finished stone graded color YZ, Strong Blue Fluoro, SI2 clarity and that just hit the 1 carat mark chosen for your DBL girdle inscription?

4) What were the primary reasons why this stone finished with a 78.1% depth with a Very Thick to Extremely Thick Girdle? (As these are unusual proportions even for a colored stone.)


OMBDBL.jpg OMBDBLPhotograph.jpg

To Answer Your Question:

Optical signature is a term describing a diamond's unique visual fingerprint. This fingerprint can be examined by considering the diamond's light return properties and virtual facet patterns.
I never thought I would owe a complete stranger demanded answers regarding my works. I guess its part of the exposure world I managed to avoid until recently. Isn't it a great picture? Can you find another one just or similar to it? (not from the DBL bank ofcourse)
 

Rockdiamond

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ETA- I was just about to post- Diagem- I hope you won't mind me answering some general questions, from my perspective.
Thanks for asking some very good questions NARRISHKEIT

Questions 1 and 2 are easy for me to answer.
The cutter buys the rough- in just about every case.

Used to be Harry Winston was a "mine to finger" operation.
They bought the rough, polished it, and sold to the public.
But such things don't exist today.
Buying rough is an incredibly specialized skill.
No retail seller I've ever heard of has this skill, or the capitol to compete as a rough buyer.
It's not economically feasible to buy a single piece of rough for a single stone. It's like that candy commercial- you can't have ( buy) just one.

3) Since Yoram supplies us, he chooses rough that is suitable for what we are looking to do- that is- have light yellow Antique Cushion Diamonds. It's entirely possible he buys a group of rough- and figures out which of his branded cuts each stone would work best for.

4) I can't answer why the stone was cut to these exact proportions- other than to say that the results are the proof of the pudding.
The stone looks to me to have a very nice size for a 1.01ct OMB
Taken out of context, 78% is"deep"
However if you consider the two main drawbacks to a 78% ( perceived deep) depth:
1) small size for the weight
2) dark center
This stone looks it's weight- and there's no deficit of light coming out of the center. In fact, it seems to be very bright- and transmits the color. And it looks it's weight- or a little bigger

Fluorescence: If I had my druthers, I'd avoid the blue stones in light yellow colors.
However, there's only one reason for that- photography. They're harder to capture on film ( bytes)
In person, many light yellows with Medium or strong blue can actually "bluff" a shade or two darker.
Plus, many people that like light yellows also like fluorescence.
In terms of value: in stones of these shades, prices are not affected by the presence of fluorescence
 

Rockdiamond

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Regular Guy|1313184252|2989639 said:
when no one is looking, moving very fast to go in front of the next person in line at the grocery...

:))
Curb your enthusiasm?
 

NARRISHKEIT

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Diagem said:
I never thought I would owe a complete stranger demanded answers regarding my works. I guess its part of the exposure world I managed to avoid until recently. Isn't it a great picture? Can you find another one just or similar to it? (not from the DBL bank ofcourse)
I can't demand anything of you nor did I want to at 1:40am your time on the Sabbath but since DBL claims that my comments about weight saving to get to 1.01 carats is "misinformation" i thought you would want to comment, guess not.

Did you cut this one as well?

GOGOMBYZ.jpg GOGOMBYZPHOTO.jpg

YZ, no fluoro VS1 1.09 AVC, ~20% larger faceup and $100 cheaper.
 

NARRISHKEIT

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Rockdiamond said:
ETA- I was just about to post- Diagem- I hope you won't mind me answering some general questions, from my perspective.
Thanks for asking some very good questions NARRISHKEIT

Questions 1 and 2 are easy for me to answer.
The cutter buys the rough- in just about every case.

Used to be Harry Winston was a "mine to finger" operation.
They bought the rough, polished it, and sold to the public.
But such things don't exist today.
Buying rough is an incredibly specialized skill.
No retail seller I've ever heard of has this skill, or the capitol to compete as a rough buyer.
It's not economically feasible to buy a single piece of rough for a single stone. It's like that candy commercial- you can't have ( buy) just one.

3) Since Yoram supplies us, he chooses rough that is suitable for what we are looking to do- that is- have light yellow Antique Cushion Diamonds. It's entirely possible he buys a group of rough- and figures out which of his branded cuts each stone would work best for.

4) I can't answer why the stone was cut to these exact proportions- other than to say that the results are the proof of the pudding.
The stone looks to me to have a very nice size for a 1.01ct OMB
Taken out of context, 78% is"deep"
However if you consider the two main drawbacks to a 78% ( perceived deep) depth:
1) small size for the weight
2) dark center
This stone looks it's weight- and there's no deficit of light coming out of the center. In fact, it seems to be very bright- and transmits the color. And it looks it's weight- or a little bigger

Fluorescence: If I had my druthers, I'd avoid the blue stones in light yellow colors.
However, there's only one reason for that- photography. They're harder to capture on film ( bytes)
In person, many light yellows with Medium or strong blue can actually "bluff" a shade or two darker.
Plus, many people that like light yellows also like fluorescence.
In terms of value: in stones of these shades, prices are not affected by the presence of fluorescence
Thanks for the responses that is good information.

1) Do you pick through his inventory prior to having them inscribed or does he designate which ones he will sell to you?
2) Do you have a right not to purchase any he has specifically set out for you?
3) Do you specify a price per carat or size you are looking for?
 

diagem

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NARRISHKEIT|1313188403|2989675 said:
Diagem said:
I never thought I would owe a complete stranger demanded answers regarding my works. I guess its part of the exposure world I managed to avoid until recently. Isn't it a great picture? Can you find another one just or similar to it? (not from the DBL bank ofcourse)
I can't demand anything of you nor did I want to at 1:40am your time on the Sabbath but since DBL claims that my comments about weight saving to get to 1.01 carats is "misinformation" i thought you would want to comment, guess not.

Did you cut this one as well?

GOGOMBYZ.jpg GOGOMBYZPHOTO.jpg

YZ, no fluoro VS1 1.09 AVC, ~20% larger faceup and cheaper 8-)
DBL markup and brand not looking so competitive.
Comparing two different creatures based on photos (which certainly display the different objectives)? Sorry I wish I could play that game with you but I have more important things on my list. Whenever you wish to get with me on a genuine academic conversation regarding Diamond cuts I will be more than happy to share my knowledge but will not communicate with you in your negative energy acts. I also would prefer you show more respect to the rather wide number of professionals/vendors that participate on this forum.

One point I want to address to the wider reading public as an education purpose.
Total Depth numbers are only part of the overal cut parameters. The correct division and complimenting ratio between pavilion depth and crown height is critical to the Diamonds beauty. A flat number doesn't say much in fancy cuts (like for example Octavia, signature Princess cuts and the huge possibilities in OldMine Cuts).
Also, the "one carat mark" stigma is finally cracking as economic realities dictate differently, cutting fine cuts in conjunction with the recent rough values fogs out the man-made value brackets between the magic weight numbers.
I guess presently nature is showing us the state of the economy weaknesses while huge manmade super powers realize they can't control the results anymore, maybe just postpone them a bit.
 

Rockdiamond

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I also agree that certain questions you have asked are beyond the bounds.

I'm interested in civil discourse.
I can say in all honesty I find painting with a broad brush- when it comes to people's motivations- to be presumptive.
That is to say- some cutters may place weight retention as a primary goal- and some cutters may produce badly cut stones if they follow that course- hopefully we can agree on that.

However it's not fair to say all cutters favor weight retention to the point they'd produce a badly cut diamond.
Sometimes you can cut it perfectly and it comes out to be 1.01cts.
Sometimes that's just where the chips fall.

Regarding the specific specimen you used for the discussion- there's nothing I can see about this stone that indicates it was compromised in any way. of course I'm used to looking at fancy colored diamonds.
The thick girdle means the stone can have the depth, yet not have an excessively steep PA.
 

NARRISHKEIT

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DiaGem said:
NARRISHKEIT|1313188403|2989675 said:
Diagem said:
I never thought I would owe a complete stranger demanded answers regarding my works. I guess its part of the exposure world I managed to avoid until recently. Isn't it a great picture? Can you find another one just or similar to it? (not from the DBL bank ofcourse)
You asked for another example I gave you one.
I thought you might have cut the AVC as well but I guess you have chosen not to answer that one.

Staying on the educational track what is the reason in the 1.01 Ct for an Extremely thick girdle?
What is the reason for an extremely thick girdle in general in vintage cushion cuts?
 

yssie

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Thanks to everyone who has responded for playing in the sandbox with me! Lots of interesting points have been brought up.



NARRISHKEIT - I know brands won't be likely to divulge all that much about their specific measures/templates/patterns. Worth asking what they are willing to share, though, no?

ACA - They are transparent about some aspects, obviously not so about others... but the fact that it is pattern-based is I think indisputable. Kenny's questions about the recipe and the ability to follow the recipe are very good ones: where do WF ESs, which fail that latter test, fall in the "precision cut" debate?

Octavia - yes, there are clear differences from one stone to the next. I assume that the design for each aspires to Karl's asymptotic ideal, but obviously I have no inside information (I hope he sees this thread, bad weekend for it I suppose!).

I don't really understand what you mean by consistent optical signature either: it is a physical impossibility for the mains on a long, skinny stone to all reflect the same angles of incident light as a squarish stone - the facets just slope differently! And of course those changes (to light manipulation and light return) all snowball. I agree that there must be some templated aspect to it, if that's what you mean, but importing a wire frame into MS Paint and changing the dimensions without keeping LW constant is going to result in a totally different wireframe, so clearly that's not the whole story.

To answer your last question - yes, I personally am using a different definition to yours - I place more importance on meeting a specific goal in a specific instance than I do on reproducing a given outcome. So I agree that your 40.8avg example exhibits precision... and a series of stones w/ 40.4-40.5-40.6-40.8-40.8-40.9-41-41.2 would also be "precision cut", to me, if I knew that that pattern was the cutter's goal. Though, of course, like Lula says, you can precisely cut something into a very ugly stone!


Thank you, RD! I'm glad to have your input. I agree that Brand is a whole different concept.. for purposes of this discussion let's just assume that Brand is whatever the vendors consider it to be - style, service, whatever.

Bad example on the 20% brighter though - dare I point out that that particular vendor doesn't exactly have a reputation for fair play or consistency ;))

What are Yoram's goals in cutting your stones? I would also be very interested to hear your/his thoughts. And Lula - thank you, too, I was hoping you'd share your thoughts - you have a unique perspective on this. I agree that precision cutting necessarily crosses the lines between science and art, and that a stone may be uselessly but precisely cut into an odious pattern... I am not so clear on whether how well a vision is executed is part of the parcel - what do you think of WF's ESs?

You, Lula, say you look for consistency across a brand. In particular, you look for consistency in both aesthetic (what I'll call the still photo look) and light return type - across rough colour, at least. Octavias, AVCs have a different model - and yet I would say these lines also observe 'brand consistency' (through the stones themselves, I mean, rather than through vendor reputation a la Tiffany). I can't pinpoint *why*. Perhaps NARRISHKEIT's optical signature idea is the closest we'll get - much as I do disgree that stones w/ originally similar faceting patterns can be considered to have the same fingerprint, depending on exactly what changes have been made.


Two pics of two incredible stones... and a really great example of different models, both of which can show "precision of cut" to very different effects. The goals of the AVC are clearly very different from the goals of the DBL - and it shows in the results. I personally couldn't say one is 'better' than the other - better for certain purposes, yes, but not objectively just 'better'. RD given that you are primarily an FCD vendor the extra saturation gleaned from a thicker girdle is only a bonus, is it not?


DiaGem - I would love to entice you into an academic discussion on diamond cutting, but I've got lots to learn still! Thank you for your thoughts - it is interesting to read that the 1ct mark may be less important than it has been.

I will say that I saw pics of a yellow and a blue EightStar posted on PS a few days ago.. and was honestly unimpressed. EightStar is another brand that clearly follows a template model of precision cutting - and the rough was put to the lathe with the same design plan as every other EightStar produced. I would rather have seen some acknowledgement that the coloured material inherently requires different machinations to either highlight or minimize the colour..
 

diagem

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Yssie|1313209497|2989857 said:
I don't really understand what you mean by consistent optical signature either:

When you are able to notice the difference between a repeatable branded cut to it's generic counterparts is what I consider a signature, since we are talking about polished Diamonds the word "optical" becomes THE main factor. I know you didn't ask me specifically but I thought I would add my 2c's


To answer your last question - yes, I personally am using a different definition to yours - I place more importance on meeting a specific goal in a specific instance than I do on reproducing a given outcome. So I agree that your 40.8avg example exhibits precision... and a series of stones w/ 40.4-40.5-40.6-40.8-40.8-40.9-41-41.2 would also be "precision cut", to me, if I knew that that pattern was the cutter's goal. Though, of course, like Lula says, you can precisely cut something into a very ugly stone!

With today's technologies available, we cutters are limited to the scan-error allowance which presently stand at 3-4 tenths of a degree, more accurate today only exists in theory.


What are Yoram's goals in cutting your stones? I would also be very interested to hear your/his thoughts. And Lula - thank you, too, I was hoping you'd share your thoughts - you have a unique perspective on this. I agree that precision cutting necessarily crosses the lines between science and art,...

My goals when cutting the DBL yellows starts by locating the correct rough material which will compliment my vision of the end product I aim to reach, cutting color is extremely tricky especially when dealing with border line material (eg lighter = Capes vs darker = costly Fancy magic words). In a way people and many other professionals which are saying I am destroying the potential outcome. If (for example) I would choose to cut the chosen material into "enhance for face-up color appearance" cuts like the Radiants or CMB's the stones would probably be graded "Fancy" by GIA and be marketed at a much higher value. Instead I decided to cut that material into a regular brilliant facet design while exploring each stone's optical potential while putting an emphasis on complimenting it's true body color with it's all around visual properties (eg profile, face up look the same). So to recap..., was I able to cut those into more saturated face up cuts? Yes probably, but the market is full of those, David & I teamed up to offer a product that does not exist on the market just because of the reasons stated above.


Two pics of two incredible stones... and a really great example of different models, both of which can show "precision of cut" to very different effects. The goals of the AVC are clearly very different from the goals of the DBL - and it shows in the results. I personally couldn't say one is 'better' than the other - better for certain purposes, yes, but not objectively just 'better'. RD given that you are primarily an FCD vendor the extra saturation gleaned from a thicker girdle is only a bonus, is it not?

Since my goal is to attempt to disperse the body color throughout the whole Diamond area (extremely hard task with lower saturated color material) I use whatever tools the material allows..., girdle thickness is one of them but to each stone the tools act different so it's not a straight rule for all my yellow cuts. This decisions are made deep within the cutting process, I can easily say each yellow "brilliant or Stepcut" stone I design & cut is another step in my R&D knowledge in this field.

DiaGem - I would love to entice you into an academic discussion on diamond cutting, but I've got lots to learn still! Thank you for your thoughts - it is interesting to read that the 1ct mark may be less important than it has been.

Whenever you have questions I would be more than happy to answer..., as long as it's for educational purposes and not for aimed attacks as some have clear interests in
 

kenny

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Thanks for that post DiaGem.
What fascinating work you do!!!

BTW, we get tons of compliments on the Octavia you cut.
I tell people about the guy who cut it. :wavey:
 

Karl_K

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Yssie|1313209497|2989857 said:
Octavia - yes, there are clear differences from one stone to the next. I assume that the design for each aspires to Karl's asymptotic ideal, but obviously I have no inside information
This is an incredibly complex subject and I cant really answer without pushing the rules.

I approve every Octavia before it is sold and if it does not pass it is worked on until it does.
There are minor differences, that is the nature of step cuts.

You can cut 2 step cuts as similar as the best step cut diamond cutters in the world can cut them and there will be differences.
It is an incredibly hard cut to cut and Yoram has spent hundreds of hours inventing new procedures so it can even be cut.

With a RB every facet(except lgf%) by the nature of the cut falls into the right location, this is why you see more h&a diamonds these days, modern tooling and procedure has allowed control of the angles and the facets fall into alignment. The lower halfs are the exception and variations in them is a lot of the time the reason a diamond is not h&a.

With step cuts not only must the cutter control the angle but also the location of the rows of facets with no meet points to guide them like with rounds and it must be done by eye.
That is where the slight variation comes from in Octavia and there is no answer for it.
 

kenny

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As long as we're on this subject . . . DiaGem, If I understand what you you wrote, today's equipment can control the angle to 3 or 4 tenths of a degree.

Would that not mean we should see Symmetry grades rising?
Isn't Symmetry a grade of the facets being placed "where the cut recipe says they belong" all around the diamond?

Please correct my understanding if it is flawed.
 

Karl_K

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kenny|1313246355|2989986 said:
As long as we're on this subject . . . DiaGem, If I understand what you you wrote, today's equipment can control the angle to 3 or 4 tenths of a degree.

Would that not mean we should see Symmetry grades rising?
Isn't Symmetry a grade of the facets being placed "where they belong" all around the diamond?

Please correct my understanding if it is flawed.
The lab symmetry grade is mainly that all of the facet meet points are meeting and not overlapping or missing each other.
Symmetry grades on average rose because if the angles are closer to each other and there is less wobble/play in your equipment you can hit the meet points easier.
 
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