Light Performance vs Color

[AshNZ]

Hi PSers, first post here:

Background - I have started looking for an e-ring. I have been checking out the HCA, Sarin, GemAdvisor (etc) scores as I am seeking an absolutely top tier cut diamond. I have been into see Bryan at WhiteFlash here in Houston and seen some lovely examples, I also visited Tiffany''s and have their agent searching their database for suitable geometric parameters (the ones in the store had horrible HCA numbers, 3.9 and worse from memory). Don''t get me started on Tiffany''s, I know I know....

I am looking for a stone that has incredible performance (ie sub 0.6 on the HCA and near perfect lower facet symmetry) and started to wonder, if I am that concerned about squeezing the last drop out of the optical geometry of the stone for light return (ignore BIC/TIC/FIC), should I be MORE concerned than the average punter about color?

A G color stone seems like a great value stone but if I am chasing the absolute BEST in light performance, would I gain I percentage or two if I went up to a F, or or D?

What I am asking is: Just how important is color to light performace. I don''t want subjective answers, I would prefer answers based on optics/physics. My guess is the impurities in a diamond that give it color are also going to attenuate the light spectrum to some degree. If I am the sort of person who wouldn''t buy anything but a <0.6 HCA/H&A (type)/VH3x3 should I only be looking at the colorless range?

Any input appreciated!


Wonderful forum and community here by the way - I learnt an incredible amount in the last few days!

Thanks
Ash

 

[Regular Guy]

Ash,

Don''t let your early exposure to the tools here guide you incorrectly.

Scores below 1 on the HCA are not better, with respect to performance, than scores above 1 and below 2.

If you''re in Houston, you have access to important resources... in contact with BG, WF, and JP at Infinity. Telling experts what you''re seeking will serve you well, but feel free to verify whatever recommendations they may give you.

 

[elle_chris]

Light performance and color don''t have anything to do with eachother until you get to the fancy color grades. It''s all about how the stone is cut. A D, if not well cut will look like a dud compared to a well cut J.

 

[stone-cold11]

HCA is a rejection tool not a selection tool.

 

[Lorelei]

Date: 10/13/2009 11:33:11 AM
Author:AshNZ
Hi PSers, first post here:

Background - I have started looking for an e-ring. I have been checking out the HCA, Sarin, GemAdvisor (etc) scores as I am seeking an absolutely top tier cut diamond. I have been into see Bryan at WhiteFlash here in Houston and seen some lovely examples, I also visited Tiffany's and have their agent searching their database for suitable geometric parameters (the ones in the store had horrible HCA numbers, 3.9 and worse from memory). Don't get me started on Tiffany's, I know I know....

I am looking for a stone that has incredible performance (ie sub 0.6 on the HCA and near perfect lower facet symmetry) and started to wonder, if I am that concerned about squeezing the last drop out of the optical geometry of the stone for light return (ignore BIC/TIC/FIC), should I be MORE concerned than the average punter about color?

A G color stone seems like a great value stone but if I am chasing the absolute BEST in light performance, would I gain I percentage or two if I went up to a F, or or D?

What I am asking is: Just how important is color to light performace. I don't want subjective answers, I would prefer answers based on optics/physics. My guess is the impurities in a diamond that give it color are also going to attenuate the light spectrum to some degree. If I am the sort of person who wouldn't buy anything but a <0.6 HCA/H&A (type)/VH3x3 should I only be looking at the colorless range?

Any input appreciated!


Wonderful forum and community here by the way - I learnt an incredible amount in the last few days!

Thanks
Ash

A lower HCA score is not better than a higher one, the HCA is used for rejection and the aim is to see which diamonds score below 2 then evaluate from there with Idealscope or ASET images. As to the title question I think that might be what you will find are subjective answers, there was a thread concerning this a while ago and I don't think the experts reached any definite conclusions. Find a well cut diamond and the beauty and performance you want will be there.

 

[Todd Gray]

Date: 10/13/2009 11:51:02 AM
Author: Stone-cold11
HCA is a rejection tool not a selection tool.

This is the best summary of the HCA that I think I''ve ever read! Thank you for stating it so succinctly.

The HCA should be used to eliminate diamonds with poor visual performance from those which are likely to exhibit better visual performance... A lower score does not necessarily indicate a visible difference once you cross over the threshold of excellence.

The body color of a diamond does not have a direct impact on visual performance which is brilliance, dispersion and scintillation - it is merely the tone of the diamond and is a matter of personal preference. Some people like myself prefer diamonds with cooler tones, such as those in the D - G range, and other people like my mother prefer diamonds which are a little warmer in color such as L,M,N, and both ends of the spectrum can provide vibrant options if the proportions of the diamond and the facet structure are carefully crafted.

 

[Lula]

I understand your interest in superior cut/mathematical perfection. I own an Infinity RB because of their beautiful visual appearance and "tight" cut.

I agree with the others, stick with stones that score < 2 on the HCA and choose color based on your/your fiancee's personal preferences. And ditto the others, if you are lucky enough to live near Whiteflash (ACA) and John Pollard (Infinity), go see the stones in person.

In addition, looking at the Helium reports for the stones will give you a better idea of their cut quality/precision. See these threads for more information on cut consistency and optical vs. physical vs. lab symmetry.


symmetry thread
cut consistency

 

[oldminer]

For a person interested in the optics and physics of the diamond, the responses you got about color not having an effect on light return are dead wrong. The tint, however light, of a diamond impacts the absolute light return characteristics. It probably will not impact the light return in a visual way between D to H, but folks should not give subjective advice when objective knowledge has been requested.

The darker the tint, however little, plays some role in how much light is absorbed, lost, and returned when measured with instrumentation more sensitive than the human eye. I believe this is what the questioner asked and is the right info.

 

[elle_chris]

Date: 10/13/2009 12:24:13 PM
Author: oldminer
For a person interested in the optics and physics of the diamond, the responses you got about color not having an effect on light return are dead wrong. The tint, however light, of a diamond impacts the absolute light return characteristics. It probably will not impact the light return in a visual way between D to H, but folks should not give subjective advice when objective knowledge has been requested.

The darker the tint, however little, plays some role in how much light is absorbed, lost, and returned when measured with instrumentation more sensitive than the human eye. I believe this is what the questioner asked and is the right info.

Really David? So you're saying between two ideal cut stons, a D will return more light than a J? And by that I'm asking will it be noticeable to the eyes?

eta: I find this very interesting as we're always talking about cut being the primary factor to how much light the stone's returning. So if color plays a role that's visible, how come no one mentions this?

 

[AshNZ]

Date: 10/13/2009 12:24:13 PM
Author: oldminer
For a person interested in the optics and physics of the diamond, the responses you got about color not having an effect on light return are dead wrong. The tint, however light, of a diamond impacts the absolute light return characteristics. It probably will not impact the light return in a visual way between D to H, but folks should not give subjective advice when objective knowledge has been requested.

The darker the tint, however little, plays some role in how much light is absorbed, lost, and returned when measured with instrumentation more sensitive than the human eye. I believe this is what the questioner asked and is the right info.

Thank you David. This was my baseline assumption. I am geophysicist by training and trade so I know a thing or two about ray tracing, reflections, refractions and absorption. I am interested in weighing up my anal retentiveness of cut vs color. If I am going to be so constraind on cut, surely I should limit myself to an appropriate color range? Understanding whether color is a 10% vs 0.1% difference in light performance is my goal.


To the other reponses: Firstly, thank you for taking the time to respond, however, I did specifically ask for non-subjective answers - for most people this is out of your league (it''s out of mine and I have 10 years in geophysics!) so please refrain unless you have a truely useful answer.

Regarding HCA - wow, talk about off-topic. I am not even going to respond any further than that.


Regards
Ash

 

[oldminer]

I will see if I can get some amount for the difference from D color to an identical G color. I am not sure anyone has really tried to measure this, but I work with someone who well may have such hard data compiled. It would not make sense to me that there is zero measurable effect, but sometimes the real answers do surprise us. As the spectrum of light goes from white light composed of all the visible colors to a less full spectrum which is missing certain wavelengths, it stands to reason that total light return has been reduced in some way. The question is how much and has anyone tried to measure it?

Some years back we had long discussion about the potential of grading near colorless diamonds simply by gray scale, tonal differences. While it sounded like a possible solution for color grading, it did not pan out since diamonds have som much hue color variation and out eyes are not equally sensitive to each distinct hue.

 

[stone-cold11]

Date: 10/13/2009 12:29:15 PM
Author: elle_chris
Really David? So you''re saying between two ideal cut stons, a D will return more light than a J? And by that I''m asking will it be noticeable to the eyes?

eta: I find this very interesting as we''re always talking about cut being the primary factor to how much light the stone''s returning. So if color plays a role that''s visible, how come no one mentions this?

Body color you see of the stone is the removal of some component of the incoming light by absorption by the diamond, so in theory, some light energy is removed from the reflected light. How much? I do not know.

 

[Todd Gray]

Sorry, I missed the request for truly ''subjective'' answers, just as other people overlook the concept of spell check and mis-spelled items are underlined in red to make them easier to detect

Will the presence of tone or color within the body of a diamond affect the amount of light that will pass through the diamond crystal? Yes. Will most people absent of ''eagle vision'' see a perceptible difference between the amount of light which passes through an F color diamond and a G color diamond or even an H color diamond if all other factors are equal, no.

Will increasing the diamond color from a G to an F result in a light gain of 1% perhaps David has data from the IMAGEM research which will provide a conclusive answer to that question. I''ll also ask Marty Haske to visit this thread and add his two cents.

 

[AshNZ]

Date: 10/13/2009 12:29:15 PM
Author: elle_chris

Date: 10/13/2009 12:24:13 PM
Author: oldminer
For a person interested in the optics and physics of the diamond, the responses you got about color not having an effect on light return are dead wrong. The tint, however light, of a diamond impacts the absolute light return characteristics. It probably will not impact the light return in a visual way between D to H, but folks should not give subjective advice when objective knowledge has been requested.

The darker the tint, however little, plays some role in how much light is absorbed, lost, and returned when measured with instrumentation more sensitive than the human eye. I believe this is what the questioner asked and is the right info.

Really David? So you''re saying between two ideal cut stons, a D will return more light than a J? And by that I''m asking will it be noticeable to the eyes?

eta: I find this very interesting as we''re always talking about cut being the primary factor to how much light the stone''s returning. So if color plays a role that''s visible, how come no one mentions this?

Elle, it is mentioned. It is just that it is probably a 10:1 ratio of importance of cut vs color. Hence cut, (and rightly so) receives significantly more attention.
It is disappointing when vendors do not understand that color plays a role in Light Performance, however small.

Gary Holloway has the 10:1 summary chart (I don''t know how subjective this is)

 

[Lorelei]

Date: 10/13/2009 12:33:01 PM
Author: AshNZ

Date: 10/13/2009 12:24:13 PM
Author: oldminer
For a person interested in the optics and physics of the diamond, the responses you got about color not having an effect on light return are dead wrong. The tint, however light, of a diamond impacts the absolute light return characteristics. It probably will not impact the light return in a visual way between D to H, but folks should not give subjective advice when objective knowledge has been requested.

The darker the tint, however little, plays some role in how much light is absorbed, lost, and returned when measured with instrumentation more sensitive than the human eye. I believe this is what the questioner asked and is the right info.

Thank you David. This was my baseline assumption. I am geophysicist by training and trade so I know a thing or two about ray tracing, reflections, refractions and absorption. I am interested in weighing up my anal retentiveness of cut vs color. If I am going to be so constraind on cut, surely I should limit myself to an appropriate color range? Understanding whether color is a 10% vs 0.1% difference in light performance is my goal.


To the other reponses: Firstly, thank you for taking the time to respond, however, I did specifically ask for non-subjective answers - for most people this is out of your league (it's out of mine and I have 10 years in geophysics!) so please refrain unless you have a truely useful answer.

Regarding HCA - wow, talk about off-topic. I am not even going to respond any further than that.


Regards
Ash

I am sure you didn't mean to come across in that way, however this is a consumer education forum where anyone can answer or request more info on the topic being discussed, and the input of anyone who tries to help you should be appreciated. An answer which might not be useful to you personally might be useful to someone else.

Also Ira, stonecold and I were trying to assist you to use the HCA in the right way as it appeared it would be helpful to you, this advice is not off topic or out of place. Consumers spend their valuable time here trying to help other consumers along with some experts for no reward other than the appreciation normally given to them for their efforts. The posters here are trying to help you as best they can and I hope you understand that.

 

[AshNZ]

L - I understand it is abrupt and I do appreciate that people take the time to respond (as I stated) - afterall, PS (and other forums) wouldn't exit without the input of the users!
However, I make no exceptions for MIS-information. I should be dealt with, otherwise it is spread and it detracts from the integrity of the forums. If people quoted 'color has no effect on Light performance - I read this on PS' to knowledgable industry folk it would have a negative effect on PS.

(Edit - as you can see I am trying to stay away from HCA in this thread - but I do appreciate the guideance!)

Just my view

Anyway - back on topic, hopefully this will get interesting!

I am also really keen to apply any learning to colored gems, I was considering a light pink (ie, just $$$, not $$$$$$$) Pink Argyle for the e-ring but was put off as I didn't think the color would allow a 'sparkly ring' which is what the GF will want

Ash

 

[oldminer]

Dr. Aggarwal, the principal of ImaGem, Inc., www.imageminc.com has advised me as follows: The light return from a D color identical in all respects to a G color would vary so little due to the color difference that it would be less than any machine error of the tool used to measure such a difference. So, in spite of what makes sense about absorption, there is no measure of less light return based on such minor color differences.

 

[stone-cold11]

I think you have a misconception between sparkling/lively and light return.

Sparkling/lively stone also takes into account of scintillation and contrast, not just light return, a effect of cutting and facet arrangement. Contrast in enhanced by control leakage and obstruction, not the best for light return. If you want the best for light return, get a piece of silver polish mirror or whatever the Hubble telescope mirror is made from.

We are trying to change how you use the HCA because it is just plain wrong. If you still want to go that course, be prepared to see a dark stone due to obstruction effect. So much for best light return, D color stone if not light is even entering the stone in the first place.

 

[AshNZ]

Date: 10/13/2009 1:13:25 PM
Author: oldminer
Dr. Aggarwal, the principal of ImaGem, Inc., www.imageminc.com has advised me as follows: The light return from a D color identical in all respects to a G color would vary so little due to the color difference that it would be less than any machine error of the tool used to measure such a difference. So, in spite of what makes sense about absorption, there is no measure of less light return based on such minor color differences.

Thanks David.

Good to know I can save my money on color.
Do you have any concept of Light Performance variation for say a D color and an equivalent light argyle pink?

Perhaps a '7p' type grade (I understand this would be much more subjective)
http://www.argylepinkdiamonds.com.au/images/middle_pic11b.jpg

Ash

 

[Rockdiamond]

Date: 10/13/2009 11:33:11 AM
Author:AshNZ
Hi PSers, first post here:

Background - I have started looking for an e-ring. I have been checking out the HCA, Sarin, GemAdvisor (etc) scores as I am seeking an absolutely top tier cut diamond. I have been into see Bryan at WhiteFlash here in Houston and seen some lovely examples, I also visited Tiffany''s and have their agent searching their database for suitable geometric parameters (the ones in the store had horrible HCA numbers, 3.9 and worse from memory). Don''t get me started on Tiffany''s, I know I know....

I am looking for a stone that has incredible performance (ie sub 0.6 on the HCA and near perfect lower facet symmetry) and started to wonder, if I am that concerned about squeezing the last drop out of the optical geometry of the stone for light return (ignore BIC/TIC/FIC), should I be MORE concerned than the average punter about color?

A G color stone seems like a great value stone but if I am chasing the absolute BEST in light performance, would I gain I percentage or two if I went up to a F, or or D?

What I am asking is: Just how important is color to light performace. I don''t want subjective answers, I would prefer answers based on optics/physics. My guess is the impurities in a diamond that give it color are also going to attenuate the light spectrum to some degree. If I am the sort of person who wouldn''t buy anything but a <0.6 HCA/H&A (type)/VH3x3 should I only be looking at the colorless range?

Any input appreciated!


Wonderful forum and community here by the way - I learnt an incredible amount in the last few days!

Thanks
Ash

Ash- you''re asking a subjective question, yet don;t want subjective answers.


Many pink diamonds sparkle just as much as D color diamonds based on human observation. A device used to measure light might be able to detect differences the human eye can not- if that''s the case, how valuable is that info?

Using devices that measure light return may provide "statistical" or "objective" data, although this is not agreed upon in the diamond trade.
But even if these devices do provide objective info, interpreting that data will always yield subjective info.

I''d say to use your eyes.
I understand you are the guy, and considering this to be given as a gift ( engagement?)
If so, do you think she will buy into all these stats, or just want a great looking stone that appeals to her visually?
Clearly there are ladies that do want to have a stone that performs well on light return tests ( judging by the people posting here)
But that is not always the case.
Sometimes a VG cut stone of greater size is far more attractive to the recipient

 

[AshNZ]

Actually David, if something is measureable, an objective answer is obtainable. David (oldminer) has taken the time to ask for clarification – the result being ‘not even measureable using current tools’. That is my objective answer.

Regarding the rest of your post – all good tips that I will take into account when I actually commit to a stone – why else do you think I am looking at Tiffany’s!! I am just trying to keep this thread as clean and as objective as possible for future PS readers who can make their own conclusion about how important this or that is to them.

Ash

 

[Rockdiamond]

You''re welcome Ash!

The reason I don''t feel the data is "objective" is that there is much debate as to whether the measurements obtained are consistent, or relevant.
This data is by no means agreed upon by the industry as a whole- of course, including Tiffany''s.

I''ve been grading and judging diamonds for over 30 years.
I do not find the data provided by these tests to be relevant.

There are plenty of folks here who disagree- making for some lively ( albeit subjective) conversation.

 

[FB.]

elle chris

Mr. Atlas is correct.

Any colour tint will be caused by the stone absorbing some of the light that enters and the absorbed light is then not able to be reflected back out. I would assume that the brightest stones of all would be the "blue-whites", which have no colour and additionally they convert invisible ultraviolet light into the far end of the visble blue spectrum - meaning light return is enhanced by the conversion of radiation into visible light.

But I suspect that the light lost in a J compared to a D would be quite small. Maybe 10% at most. Probably less.
Quite likely, having some fluorescence in a lower colour would offset the light absorbed by the body colour.

If we want to get "purist" about light return, then you also need to consider that unless the stone is internally flawless, the inclusions within will affect brilliance. Again, only by a small amount. An "eye clean" SI2 might be noticeably less brilliant if the grade-setters are clouds.

I have seen some people mention on here that very low HCA scores (below 0.7) start to suffer optical anomalies and that the best stones have a score of about 1-1.5.

AshNZ
Although the decisions are yours to make, I would say that it sounds as if you're getting trapped into a corner where only a super-ideal, D colour, internally flawless stone (costing $$$$$ or being very small in size to be within budget) will be acceptable to you.
But as always; the cut is most important. The colour next most important and the clarity next most important.

Personally, I'd settle for an ideal cut, HCA 1-2, F, VS2.

 

[kenny]

Ash, a well-cut white diamond is cut to maximize light return out the crown.

Pink diamonds are not.
They are cut to maximize the strength of the pink color.
This results in completely different set of decisions when it comes to angles and proportions.

To maximize the color they may orient the cut so internal pink graining lines are at 45 degrees with respect to the table.
Even the cut they pick can strengthen the color; A radiant makes the light bounce around more times through the colored material before exiting out the top.
When successful a skilled cutter can raise the color grade from fancy pink to fancy intense pink, which makes the price skyrocket - all from the same piece of rough.
They'd be nuts to cut for light performance (ending up with a lower color grade) and throw thousands of dollars away.

If you want a pink diamond that has light performance as good as a well-cut white diamond you are not going to find it, unless you actually commission the cutting of some pink rough yourself.
Then YOU will be throwing away thousands of YOUR dollars, but if a pink with good light performance is your goal that's how you'll get it.
Instead of rough, you could buy a 2-carat cut fancy intense pink, get it recut, and end up with a 1.2 carat fancy pink.

Oh and once you get under 2 lower is not necessarily better with the HCA score.

 

[adamasgem]

Date: 10/13/2009 11:45:02 AM
Author: elle_chris
Light performance and color don''t have anything to do with eachother until you get to the fancy color grades. It''s all about how the stone is cut. A D, if not well cut will look like a dud compared to a well cut J.

Unfortunately, you are dead wrong in your statement about light performance and color in your opening statement and then you correct yourself in the second and third sentances.

Ypu will always absorb some light entering and within a stone, but the cutting can either minimize or accentuate the effect.

Two examples, Richard Von Sternberg of Eightstar wears a K color EightStar which faces up like an H-I, and others here on the forum may have seen it and can verify what I say.

Optical symmetry, when combined with the proper set of crown and pavilion angles, can MINIMIZE the light path though the diamond, and therefore minimize internal absorption, such that the exiting rays are whiter than a poorer sut stone.

Conversely, manufacturers of yellow Radiant cuts, in particular, have learned how to MAXIMIZE internal absorption, and get an unusual amount of "Lucky Vivids" by just a little tweek in the angles.

 

[Rockdiamond]

Date: 10/13/2009 2:11:12 PM
Author: kenny
Ash, a well-cut white diamond is cut to maximize light return out the crown.

Pink diamonds are not.
They are cut to maximize the strength of the pink color.
This results in completely different decisions when it comes to angles and proportions.
They may orient the cut so internal pink graining lines are at 45 degrees to the table and pick a cut, like radiant or pear.
These cuts makes the light bounce around more times through the colored material before exiting out the top, which intensifies the color more.

When a cutter is successful doing this it can raise the color grade from fancy pink to fancy intense pink, which makes the price skyrocket - all from the same piece of rough.
They''d be nuts to cut for light performance (ending up with a lower color grade) and throw thousands of dollars away.

If you want a pink diamond that has light performance as good as a well-cut white diamond you are not going to find it, unless you actually commission the cutting of some pink rough yourself.
Then YOU will be throwing away thousands of dollars, but if a pink with good light performance is your goal this is how to get it.

Oh and once you get under 2 lower is not necessarily better with the HCA score.

Kenny- isn''t this generalzing a bit too much?
Clearly, there are pinks that are cut for color, over other factors.
But that''s not always the case.
What if the grain lines just so happen to fall in a way that the cutter can get the most pink color and not have to give up what you term "light performance".
I have seen many such pink diamonds.
We might be abler to "prove" a colorless stone returns more light, but we again get back to the point about machines measuring things we can not see.

 

[kenny]

RD, yes perhaps when cutting to optimize color strength you may occasionally happen to end up with good light performance too.

But I think the following principle is sound:
With fancy colored rough there is MUCH more financial reward in cutting to achieve a higher color grade than in cutting to achieve better light performance.

 

[AshNZ]

Date: 10/13/2009 2:11:02 PM
Author: FB.
elle chris

Mr. Atlas is correct.

Any colour tint will be caused by the stone absorbing some of the light that enters and the absorbed light is then not able to be reflected back out. I would assume that the brightest stones of all would be the ''blue-whites'', which have no colour and additionally they convert invisible ultraviolet light into the far end of the visble blue spectrum - meaning light return is enhanced by the conversion of radiation into visible light.

But I suspect that the light lost in a J compared to a D would be quite small. Maybe 10% at most. Probably less.
Quite likely, having some fluorescence in a lower colour would offset the light absorbed by the body colour.

If we want to get ''purist'' about light return, then you also need to consider that unless the stone is internally flawless, the inclusions within will affect brilliance. Again, only by a small amount. An ''eye clean'' SI2 might be noticeably less brilliant if the grade-setters are clouds.

I have seen some people mention on here that very low HCA scores (below 0.7) start to suffer optical anomalies and that the best stones have a score of about 1-1.5.

AshNZ
Although the decisions are yours to make, I would say that it sounds as if you''re getting trapped into a corner where only a super-ideal, D colour, internally flawless stone (costing $$$$$ or being very small in size to be within budget) will be acceptable to you.
But as always; the cut is most important. The colour next most important and the clarity next most important.

Personally, I''d settle for an ideal cut, HCA 1-2, F, VS2.

Very interesting point about the ''blue-whites''. I followed up by reading this:
http://diamonds.pricescope.com/fluor.asp

So, the ultimate light performance diamond would have the ideal cut, no color but have some degree of fluoresence. Interesting, I was avoiding Flu stones...

Ash

 

[AshNZ]

Date: 10/13/2009 2:11:12 PM
Author: kenny
Ash, a well-cut white diamond is cut to maximize light return out the crown.

Pink diamonds are not.
They are cut to maximize the strength of the pink color.
This results in completely different set of decisions when it comes to angles and proportions.

To maximize the color they may orient the cut so internal pink graining lines are at 45 degrees with respect to the table.
Even the cut they pick can strengthen the color; A radiant makes the light bounce around more times through the colored material before exiting out the top.
When successful a skilled cutter can raise the color grade from fancy pink to fancy intense pink, which makes the price skyrocket - all from the same piece of rough.
They''d be nuts to cut for light performance (ending up with a lower color grade) and throw thousands of dollars away.

If you want a pink diamond that has light performance as good as a well-cut white diamond you are not going to find it, unless you actually commission the cutting of some pink rough yourself.
Then YOU will be throwing away thousands of YOUR dollars, but if a pink with good light performance is your goal that''s how you''ll get it.
Instead of rough, you could buy a 2-carat cut fancy intense pink, get it recut, and end up with a 1.2 carat fancy pink.

Oh and once you get under 2 lower is not necessarily better with the HCA score.

Another great point relevant to this thread. Effectively, the longer the ray path is, the more absorbtion of color of that part of the light spectrum, the more intense the stone appears. It goes to show that it is a cut and color combination which makes the difference due to ray path length.

So, cuts with steep/deep are more affected by color in a Round Brilliant. However, as stated earlier, the light performance decline is so minimal in RB''s it can''t/hasn''t been measured.

Ash

 

[FB.]

Blue-whites are a matter of personal taste, with their "cold", icy colour and lilac tints. The personal taste issue is similar to those who prefer "warm" colours in the slightly tinted yellow grades - K-M colour.

I recently posted some pictures of my own "blue-whites" with lab-graded "very strong blue" fluorescence and you ought to take a look before going too far down that route.

Perhaps a better use of fluorescence to increase light return would be a slight to moderate amount in a near-colourless stone.

I would suggest not going above medium fluor unless you want the stone to turn very blue at times.


Link here:
https://www.pricescope.com/community/threads/strong-blue-fluorescence.126864/