New Diamond 'upgrade' what makes it really shine?

[John P]

If you remember buying it as a 1.26 cut stone, that would make it just under 7mm if it is well cut. If it is shallow, it would probably measure over 7mm and if deep (which is what I suspect based on the look of your ring shank width) then it will be definitely under 7mm. Those are the ones that tend to not lose much diameter in a recut, just weight.

Recut shorthand: Big table, low crown, shallow, wavy, will lose significant weight in any recut. Small table, high crown, deep, even, will lose weight but perhaps not too much diameter (nicely said bc). Longer story: Girdle details (esp naturals, feathers or wave), roundness and internal characteristics all have influence. A rough estimate can be made based on mm measurements, table size and crown height. A meaningful estimate must be made by an expert with the diamond in hand.

 

[John P]

(Apologies for highjacking the thread!!!)

And I'm a repeat offender. Cokewithvanilla, if you prefer we take the tech-talk elsewhere just say the word.

Ideal-scope uses a light source underneath the diamond. Areas where light passes through the diamond, instead of returning to the viewer's eyes, show up as white or a lighter shade of red. A diamond with robust light return will have black pavilion mains (aka arrows), reflecting the black cap, and strong even red with small, symmetrical white-points of contrast leakage.

John, this was an incredibly informative post, and potentially answers a question that has been bugging me for a long time. I bolded an area that I've been wondering about - what are the small, symmetrical points of contrast leakage? Is it the stuff I've circled in blue or the stuff I've circled in black? Or both?

Based on what I've read, I assume the stuff in blue is true leakage since it's the white background, but what's the lighter red/pink in black?

The areas in black aren't leakage. The strength of backlighting, choice of photo methodology and age of the instrument can influence evenness of saturation. Leakage or windowing is not so nuanced.

The blue you identified is contrast-leakage. In a well-cut diamond these points will be symmetrical and most notable adjacent to the crown/pavilion main meet-points (your circle at 11:00) and upper-half/star meet points (your circle at 1:00).

There's a method for eliminating contrast leakage called painting. This is when the upper halves are polished to bring their angles closer to one another. However, that change in indexing creates less robust light return along those facet lines. You can see this in ASET more easily than Ideal-scope. After a certain degree GIA and AGS both penalize the reduction of contrast leakage.




Full article with more information here:
http://www.pricescope.com/journal/visible_effects_painting_digging_superideal_diamonds

 

[bunnycat]

(Apologies for highjacking the thread!!!)

And I'm a repeat offender. Cokewithvanilla, if you prefer we take the tech-talk elsewhere just say the word.

Ideal-scope uses a light source underneath the diamond. Areas where light passes through the diamond, instead of returning to the viewer's eyes, show up as white or a lighter shade of red. A diamond with robust light return will have black pavilion mains (aka arrows), reflecting the black cap, and strong even red with small, symmetrical white-points of contrast leakage.

John, this was an incredibly informative post, and potentially answers a question that has been bugging me for a long time. I bolded an area that I've been wondering about - what are the small, symmetrical points of contrast leakage? Is it the stuff I've circled in blue or the stuff I've circled in black? Or both?

Based on what I've read, I assume the stuff in blue is true leakage since it's the white background, but what's the lighter red/pink in black?

The areas in black aren't leakage. The strength of backlighting, choice of photo methodology and age of the instrument can influence evenness of saturation. Leakage or windowing is not so nuanced.

The blue you identified is contrast-leakage. In a well-cut diamond these points will be symmetrical and most notable adjacent to the crown/pavilion main meet-points (your circle at 11:00) and upper-half/star meet points (your circle at 1:00).

There's a method for eliminating contrast leakage called painting. This is when the upper halves are polished to bring their angles closer to one another. However, that change in indexing creates less robust light return along those facet lines. You can see this in ASET more easily than Ideal-scope. After a certain degree GIA and AGS both penalize the reduction of contrast leakage.




Full article with more information here:
http://www.pricescope.com/journal/visible_effects_painting_digging_superideal_diamonds

Awesome info!

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....


And don't worry CokeWV- I'm still hangin' in there with you but I am also with them too!

John gave you some good info about your stone. An appraiser should at least be able to give you basic info (diameter, depth and table size) if you can't find or get the info on your current stone, but as he rightly says, real in depth info would need to come from the person who would assess the recut possibilities. I suggested finding the basics so you can at least decide if it is an idea worth looking in to.

 

[Karl_K]

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....

Marketing is the biggest one...
no leakage!! all red scope image no white spots!!!!
Shhhh Never mind the negative impact on scintillation.

 

[bunnycat]

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....

Marketing is the biggest one...
no leakage!! all red scope image no white spots!!!!
Shhhh Never mind the negative impact on scintillation.

Thank you Karl_K... They never give up....

 

[John P]

Full article with more information here:
https://www.pricescope.com/journal/visible_effects_painting_digging_superideal_diamonds

Awesome info!

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....

And don't worry CokeWV- I'm still hangin' in there with you but I also with them too!

The article I composed in the link above is dry, but answers the question you asked.

A word about contrast: Contrast is created by obstruction (sometimes nicknamed head shadow). In a well-cut diamond, vivid effects occur when you tilt the diamond and areas that were dark in the ideal-scope image flare with light-return, while some areas that were red in ideal-scope go dark. Tilt the diamond another degree and they swap again. Move the diamond steadily through different degrees and the pattern of "on-off" brightness, disperion and contrast are what we perceive as scintillation.

So primary contrast is best created by balanced, symmetrical dark areas seen in ideal-scope (like the arrows pattern). The balance and crispness of this pattern influences the character of the scintillation.

Secondary contrast comes from the meet-point leakage we are discussing in the last posts. Prior to computer ray-tracing and light performance modeling, the elimination of those tiny leakage points was presumed to be positive (an all-red Ideal-Scope means 100% light return, right?). Also, in terms of taste, some enthusiasts sought such diamonds because, in moderation, upper-half painting gives a more fluid character to the scintillation. Some loved this. Others did not. With that said, they're rarely if ever seen any more due to the potential for being penalized after a certain degree.

 

[John P]

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....

Marketing is the biggest one...
no leakage!! all red scope image no white spots!!!!
Shhhh Never mind the negative impact on scintillation.

Thank you Karl_K... They never give up....

Careful bunnycat. You're associating with a known extremist. I take a more moderate view. Some people loved that look (still do).

 

[Lore]

The areas in black aren't leakage. The strength of backlighting, choice of photo methodology and age of the instrument can influence evenness of saturation. Leakage or windowing is not so nuanced.[/quote]

Thank you John, I learned something useful today!

I've seen a lot of Idealscope images where it appears to be whiter in only some areas under the table. Is THAT leakage then, or is that also due to the equipment/photo skills? See the new image.

 

[bunnycat]

John- I know there is probably a thread somewhere, but why would people try to eliminate the contrast? You need some contrast for a well balanced stone....

Marketing is the biggest one...
no leakage!! all red scope image no white spots!!!!
Shhhh Never mind the negative impact on scintillation.

Thank you Karl_K... They never give up....

Careful bunnycat. You're associating with a known extremist. I take a more moderate view. Some people loved that look (still do).

 

[Karl_K]

Careful bunnycat. You're associating with a known extremist. I take a more moderate view. Some people loved that look (still do).

lol... if someone is making a "fully informed decision" and likes the look then that's kewl.
A gia vg due to crown painting that's otherwise well cut can be a great value and look better than some steep deep gia ex stones.
My biggest problem was the marketing was not providing full information.
They can be beautiful but there is a compromise.

 

[John P]

Careful bunnycat. You're associating with a known extremist. I take a more moderate view. Some people loved that look (still do).

lol... if someone is making a "fully informed decision" and likes the look then that's kewl.
A gia vg due to crown painting that's otherwise well cut can be a great value and look better than some steep deep gia ex stones.
My biggest problem was the marketing was not providing full information.
They can be beautiful but there is a compromise.

Agreed, but at different levels. Definitive compromise for 8* which painted out to a full 2 clicks on the tang; blanket VG. Negligible to some compromise for NL, painted to 1 click; remained EX. The former was far more visible. The latter was a balance of factors.

 

[John P]

Thank you John, I learned something useful today!

I've seen a lot of Idealscope images where it appears to be whiter in only some areas under the table. Is THAT leakage then, or is that also due to the equipment/photo skills? See the new image.

You're welcome. What you're circling here is negligible. No visible impact on basic brightness.

 

[gm89uk]

Thanks for info guys. The 'leakage' in blue is not frank leakage, but slightly reduced light return. It is much more red than it is white like the contrast points.

 

[Karl_K]

back lighting only diamcalc default tolk ideal cut virtual diamond.
In other words this represents a perfectly cut best case RB diamond which does not exists nor possible in the real world.

 

[cokewithvanilla]

I can't even begin to digest all of this. But that diamond that we were talking about appears to be off the table now. They are bringing in a stone, and taking images of it for me, which they should have sometime next week. I dont believe the stone that they are talking about to be good. it has a shallow crown angle of 32.5 i think

I liked that perfect image one.. gives me something to reference. Does anyone have perfect ideal scope, aset, and hearts and arrows pictures ?

 

[bunnycat]

I can't even begin to digest all of this. But that diamond that we were talking about appears to be off the table now. They are bringing in a stone, and taking images of it for me, which they should have sometime next week. I dont believe the stone that they are talking about to be good. it has a shallow crown angle of 32.5 i think

I liked that perfect image one.. gives me something to reference. Does anyone have perfect ideal scope, aset, and hearts and arrows pictures ?

Hearts and arrows just shows symmetry. It does not show light performance, and you pay a premium for diamonds that are cut for hearts and arrows. I do not think that premium is necessary for you or easy to find in your situation and I also don't think you will get it at the size, color and clarity you want in your current budget. Hearts and arrows patterns generally are not an accident. They are planned in a stone and it wastes diamond rough to plan a stone to have them, and most of the time you find stones with them, they are "branded cuts" (in other words, cut for a specific company's specifications- like Whiteflash A Cut Above, Brian Gavin Signature, James Allen True Hearts, etc...and you pay more for that and don't necessarily find it at random in a stone.)

What YOU need is decent light performance. You need an idealscope image to assess that. A nice idealscope image look like this:



***IMPORTANT INFO HERE**** The problem with the red and black image they sent you of the other stone was that they seem to have *tried* to make their own Idealscope to send you that picture that had all those odd white areas. And they did it by dismantling a hearts and arrows viewer and so it didn't work as intended. And that is how your thread got derailed about idealscope images for 2 pages. Sorry.... That's the gist of the last 2 pages.

So, what would probably be MORE helpful for you is to copy this information below down and ask them for stones that have specs that fit in this range:

Table: 54-58

Depth: 60-62.3

Crown Angle: 34-35.0 (up to 35.5 crown angle can sometimes work with a 40.6 pav angle)

Pavilion Angle: 40.6-40.9 (sometimes 41.0 if the crown angle is close to 34)

 

[Garry H (Cut Nut)]

There is a very large difference between the intensity of the paler colors in an ideal-scope and the reduction in power.
Roughly half as saturated pink = a 25% drop off in light return for that zone.
This is reduced even further by the fact that we have 2 eyes and where one eye may see leakage the other may see a bright return. In that case the perceived brilliance that results from the cognitive dissonance in the mind is true brilliance - i.e. if both eyes saw strong light return the result is less brightness, and little brilliance when compared to one eye seeing dark and the other bright.
People here - you tend to over think tiny glitches in ideal-scope and ASET images. Thousands of amazing diamonds, often with better prices, have been passed over because of a search for perfection.

Image from this 2013 article on page 94. http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf
There is a link in the article for the actual experiment for those that have access to stereoscopic computer screens, and possibly may work with virtual reality headsets also.

 

[cokewithvanilla]

Thanks for the images, this will help. I am not exactly sure what you mean, Garry. Sounds like you are saying not to worry about spots, but the overall picture.

So, things have been developing over here with SB. They got with me about that 1.36 shallow cut diamond, and I said that I think it was too shallow, they brought it in anyway. Got an email from him saying "got it, but rejected it".. i asked why... he responded "Material was a bit off, should have been brighter. Had nothing to do with cut"

Material was off? What's that mean?

 

[John P]

Material was off? What's that mean?

Possibly haze or tint.

Dialogue from a few days ago: << It's a thorny topic but grading reports don't disclose haze or over-fluorescence, nor do they disclose microscopic brown or green tint. The tint situation has become more prevalent as long-standing mines are reaching their limits. You won't find this on retail sales sites, but B2B wholesalers now add a line to diamond listings to verify "No BGM" (no brown/green/milky). Those diamonds are reliably discounted. If buying blind, this area is where it's good to have an expert you trust with a gemological microscope on your side. >>

Thread here: https://www.pricescope.com/communit...ds-blind-do-you.228115/#post-4116819#p4116819

 

[Garry H (Cut Nut)]

Thanks for the images, this will help. I am not exactly sure what you mean, Garry. Sounds like you are saying not to worry about spots, but the overall picture.

When you identify a small leakage zone in an ideal-scope that is pale pink (half the saturation), then perhaps the light return is 3/4's of the deeper red parts. If that leakage zone is 2% of the surface area of the diamond, then the diamond may be.
2% x 25% = less than 1% reduction in light performance.
But this only holds true for looking at the diamond with one eye closed, and straight on.
When you have 2 eyes open, it is very likely the tiny leakage zone will not be a leakage area when viewed from the different direction of the other eye.
So my message is that unless your goal is a totally mind clean perfect H&A's with top precision in evidence (and if that is what your heart and head is set on, then pay the money and enjoy) - I suggest you buy the best priced biggest diamond for your money with great light return as evidenced by these tools.

BUT as John mentioned - there is a difference between diamond material. e.g. the inhouse diamonds always cost more than the virtuals - and a lot of the virtuals are goods that have been rejected by the top online vendors that invest their hard earned money. On top of that regular retailers and better jewelry manufacturers as the sales reps at the diamond cutters houses to look at the stones and check for such things. I sent 2 requests to one of my sources a few hours ago to check stones for "life".

 

[gm89uk]

There is a very large difference between the intensity of the paler colors in an ideal-scope and the reduction in power.
Roughly half as saturated pink = a 25% drop off in light return for that zone.
This is reduced even further by the fact that we have 2 eyes and where one eye may see leakage the other may see a bright return. In that case the perceived brilliance that results from the cognitive dissonance in the mind is true brilliance - i.e. if both eyes saw strong light return the result is less brightness, and little brilliance when compared to one eye seeing dark and the other bright.
People here - you tend to over think tiny glitches in ideal-scope and ASET images. Thousands of amazing diamonds, often with better prices, have been passed over because of a search for perfection.

Image from this 2013 article on page 94. http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf
There is a link in the article for the actual experiment for those that have access to stereoscopic computer screens, and possibly may work with virtual reality headsets also.

So would this indicate non H&A could have better theoretical brilliance than uniform perfect H&A?

 

[Garry H (Cut Nut)]

There is a very large difference between the intensity of the paler colors in an ideal-scope and the reduction in power.
Roughly half as saturated pink = a 25% drop off in light return for that zone.
This is reduced even further by the fact that we have 2 eyes and where one eye may see leakage the other may see a bright return. In that case the perceived brilliance that results from the cognitive dissonance in the mind is true brilliance - i.e. if both eyes saw strong light return the result is less brightness, and little brilliance when compared to one eye seeing dark and the other bright.
People here - you tend to over think tiny glitches in ideal-scope and ASET images. Thousands of amazing diamonds, often with better prices, have been passed over because of a search for perfection.

Image from this 2013 article on page 94. http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf
There is a link in the article for the actual experiment for those that have access to stereoscopic computer screens, and possibly may work with virtual reality headsets also.

So would this indicate non H&A could have better theoretical brilliance than uniform perfect H&A?

No reason I can think of to support that idea???
But stones like symetrical emerald cut that have a large dark zone when viewed with ASET or ideal-scope from front on can have good light return to each eye, and I have stones like that with very poor AGS PGS light return scores, but look very nice to humans. Some of that though is because AGS use way too much head obstruction of potential light sources )IMHO). Read on from page 94 to page 99 of that article I posted.
Plus Bruce Harding will be posting a new (actually very old) of his brilliant one page explanations of some of this - he wrote the 1970's article that was ignored for decades on this topic.

 

[gm89uk]

There is a very large difference between the intensity of the paler colors in an ideal-scope and the reduction in power.
Roughly half as saturated pink = a 25% drop off in light return for that zone.
This is reduced even further by the fact that we have 2 eyes and where one eye may see leakage the other may see a bright return. In that case the perceived brilliance that results from the cognitive dissonance in the mind is true brilliance - i.e. if both eyes saw strong light return the result is less brightness, and little brilliance when compared to one eye seeing dark and the other bright.
People here - you tend to over think tiny glitches in ideal-scope and ASET images. Thousands of amazing diamonds, often with better prices, have been passed over because of a search for perfection.

Image from this 2013 article on page 94. http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf
There is a link in the article for the actual experiment for those that have access to stereoscopic computer screens, and possibly may work with virtual reality headsets also.

So would this indicate non H&A could have better theoretical brilliance than uniform perfect H&A?

No reason I can think of to support that idea???
But stones like symetrical emerald cut that have a large dark zone when viewed with ASET or ideal-scope from front on can have good light return to each eye, and I have stones like that with very poor AGS PGS light return scores, but look very nice to humans. Some of that though is because AGS use way too much head obstruction of potential light sources )IMHO). Read on from page 94 to page 99 of that article I posted.
Plus Bruce Harding will be posting a new (actually very old) of his brilliant one page explanations of some of this - he wrote the 1970's article that was ignored for decades on this topic.

I was referring to your comment above in bold, where a H&A bright consistent light return would be more likely to have bright light return to both eyes simultaneously compared to one where one eye may see leakage the other may see a bright return. But I guess that would happen when the diamond is tilted anyway to one eye. I'll have a read!

 

[Garry H (Cut Nut)]

In that case the perceived brilliance that results from the cognitive dissonance in the mind is true brilliance - i.e. if both eyes saw strong light return the result is less brightness, and little brilliance when compared to one eye seeing dark and the other bright.

I was referring to your comment above in bold, where a H&A bright consistent light return would be more likely to have bright light return to both eyes simultaneously compared to one where one eye may see leakage the other may see a bright return. But I guess that would happen when the diamond is tilted anyway to one eye. I'll have a read!

For others who are reading this, and you GMUK, when a diamond has a high level of symmetry it flashes on and off with wonderful crispness.
Whether that level of symmetry needs to be H&A's is a debatable moot point. I have a standing bet offer for a real test with 10 stones for the H&A's fans to pick the non H&A's from the real H&A's stones. No one has been game to take me on.

One thing I know and maybe others have not thought about - H&A's in a half carat is not as important as it is in 2-3ct size. But in 10ct size i would bet a VG or even Good symmetry stone would look better than a H&A's.

And yes, the opportunity for leakage, or obstruction to be opposite eye matched to brightness would be the same.

 

[Karl_K]

back lighting only diamcalc default tolk ideal cut virtual diamond.
In other words this represents a perfectly cut best case RB diamond which does not exists nor possible in the real world.

I was going to follow up on this but didn't get back. Then I had a John P length post ready to go
and hit submit and the board shuddered and lost it.
So the short version....
Even the theoretical perfectly cut diamond has secondary light path light leakage in areas that show red in IS.
That means the diamond is drawing light from the front and back in those areas.
What is weird about optics in complex reflector/refraction systems is that one does not necessarily diminish the other.
The light return out the top from the top is much stronger so that is what you would normally see.*
However if the back light in IS is bright the very secondary light path leakage will turn the areas pink.
The areas that only draw light from behind the diamond stay white.

diamond 202 the difference between leakage caused by critical angles and secondary light path leakage is that that critical angle leakage is drawing light from directly behind it where secondary light path leakage is almost always sourced from the other side of the diamond pavilion.
diamond 202 other things that can increase both types of leakage are tilt, oils, yaw, slope variation, and non-flat facets.
*diamond 202 secondary light path leakage can at time be the only light that is returned to the eye in an area of the diamond even without strong backlighting.
This is more common in fancy cuts but happens with tilt in an RB also.

 

[Karl_K]

Thanks for the images, this will help. I am not exactly sure what you mean, Garry. Sounds like you are saying not to worry about spots, but the overall picture.

When you identify a small leakage zone in an ideal-scope that is pale pink (half the saturation), then perhaps the light return is 3/4's of the deeper red parts. If that leakage zone is 2% of the surface area of the diamond, then the diamond may be.
2% x 25% = less than 1% reduction in light performance.

My opinion:
The pale pink areas are actually brighter than the other areas under ideal scope lighting with strong back lighting.
In the real world there is little to no back lighting overall light return would not likely be impacted very much if at all by the secondary light path even in the areas that are pink in IS.

Anyway my take away is don't worry about pink to much is IS images unless it is a large area that looks different than anywhere else on the diamond.

 

[Karl_K]

My opinion:
The pale pink areas are actually brighter than the other areas under ideal scope lighting with strong back lighting.

Well I was wrong and I was right the angle caused leakage areas are the brightest.
The pink areas are next brightest.
This is an is image converted to grey scale based on a luminosity conversion.

 

[Karl_K]

*diamond 202 secondary light path leakage can at time be the only light that is returned to the eye in an area of the diamond even without strong backlighting.
This is more common in fancy cuts but happens with tilt in an RB also.

On further thought The ring of death in steep deeps is an example of it happening with rounds.

 

[bunnycat]

*diamond 202 secondary light path leakage can at time be the only light that is returned to the eye in an area of the diamond even without strong backlighting.
This is more common in fancy cuts but happens with tilt in an RB also.

On further thought The ring of death in steep deeps is an example of it happening with rounds.

Karl- I'm curious about the tilt part. I know the ring of death in the steep/deeps (my very first stone from about 30 years ago....) but is the secondary light path leakage common on RB's at tilted angles?

 

[Karl_K]

but is the secondary light path leakage common on RB's at tilted angles?

yep happens with all diamonds.
first image is ASET black. The background behind the diamond is black. Black is leakage.
second image exactly the same but ASET with a white background. White is leakage.
Compare the black areas with the white, noticed there is more white than black.
The leakage of all types did not change just the back lighting changed.
In the areas where there is leakage rather than secondary light path leakage it will be white in one and black in the other in the same place.