How lighting can influence on grade appearance

[Serg]

Hi all,

Please look how a remarkable round stone (second from left) can be turned to ugly look after only one change in lighting conditions.

Who may say now that lighting can NOT change cut quality grade? That a good diamond will be better than a bad diamond under any lighting?

Out of these two lightings one is standard for consumers and the other one is standard gemological color and sometimes cut grading environment.

Exposure time was automatically choosed by camera. Human eyes are adopted to lighting similar way and percept this effect the same way.


Questions:

1) Which cut is better (round or princess)?
2) What we did with lighting?
3) Which type of lighting is similar with lab color environment grading?


Sergey and Yuri.

 

[jszweda]

Hi.

Let me try and answer some of your questions as best as I can.

On the lighting, the best thing to do is to use what is known as darkroom illumination. Use 2 5500K flourescent lamps with a color refractive index of 91 or better. You can get those from a jeweler supply with ease. That is the standard for color grading diamonds. Lighting can affect the appearance of any stone, especially if it is colored. Don''t go using incadescent lights to grade stones with. That doesn''t work.

Now as far as which cut is better, better is a matter of preference. Someone might say that a princess cut is better than the round, and vice versa. Personally I like Portugueese rounds best.

Now having said that, you could test for brilliance and symmetry of a diamond and loupe the thing to see for tell tale signs of the polish. One may be a better quality of a cut than the other, not because of the shape but because of the skill of the lapidary.

Now if you''re trying to sell any of those stones, rounds tend to be more popular than princess cuts. Is one better than the other? Technically no. I would try to test each of those stones for brilliance though. You could have 2 rounds, both with excellent polish, but the proportions in the pavillion and crown could cause variant brilliance. I would say if you had 2 rounds of the same weight, the same holds true.

My advice to you is to find a good gemologist and have them document it, or if you want to see for yourself, get a dichroiscope and study these things under a jewelers lamp. I also would look for someone who has a true set of grading stones to color grade them. The CZ one''s don''t work.

HTH

 

[solange]

I had a confusing experience with color and posibly cut. I bought a 4.10 I color which was described by the vendor as Ideal cut--excellent proportions.

A friend of mine recently got engaged and her ring is somewhat smaller than mine--probably in the 3 carat range. In her office, her stone looked much whiter and brighter than mine and I began to think that maybe I was more color sensitive than I thought.

Then we met under different lighting circumstances and her stone still did look a little whiter but my stone was far more sparkly and lively.

Of course I did not ask, and she probably does not know, the cut quality of her ring. The only point I am making is that under one lighting condition, her stone looked much better than mine and in another lighting condition, my stone had a lot more life and very little difference in color.

I do not know if cut quality made the difference or just that each ring had lighting situations that were better for that particular stone.

 

[jszweda]

It could be a little of both, and an I color diamond is within that white range. These things can be subjective to the naked eye, granted.

Did the vendor ever tell you what the brilliance was on the stone? There is a technical criteria as to how brilliance is determined. It can be influenced greatly by proportions of the cut, and the actually clarity of the stone. There is a way to measure the amount of light reflected back when you illuminate the stone.

Lighting can be deceptive sometimes, and the most accurate way to tell either way would be to place them both under a jewelers lamp.

 

[solange]

I do not know the brilliance of the stone. It certainly does not fall into the best on Garry''s chart. Measurements are 59.9 depth, 56.7 table, 40.6 pavillion angle and 34.3 crown angle.
To my untrained eyes and those around me it looks beautiful. I am sure it could be more beautiful if I had paid more or gotten a smaller stone for the price. But it serves my requirements.
I do not think my eyes are sophisticated enough to see small nuances.

 

[jszweda]

Those proportions sound like they are in the "ideal" range, but I could be mistaken. My guess is that either that pavillion may be a little shallow which could affect the brilliance or the other stone you saw may have been a brilliant round versus the standard round.

If you look at 2 stones of the same size and weight, a brilliant round (also known as a Portuguesse round) may appear to be more brilliant due to the extra facets on the pavillion.

Do you have any of the specs on the stones clarity?

 

[oldminer]

I really don''t wish to be argumentative. Nevertheless, changing lighting demonstarates the obvious. Turn off the lights and all of the diamonds would grade the same. Turn them on until the entire screen is nearly white and they all will grade about the same, too.

What is needed is sufficient light, not too much or too little, with which to judge the effectivenesss of the cut.

 

[Serg]

re:What is needed is sufficient light, not too much or too little, with which to judge the effectivenesss of the cut.

Dave, Both light scheme have sufficient light.

One scheme is close to consumer light scheme, other is close to professional scheme.

What can you say about my current example?

 

[jszweda]

Just to clarify, when you say "grade", do you mean for clarity, color or everything?

 

[Serg]

Date: 1/13/2006 3:06:42 PM
Author: jszweda
Just to clarify, when you say ''grade'', do you mean for clarity, color or everything?

If you are asking about name topic, I mean "grade appearance".

 

[jszweda]

Well then, you illustrate Dave''s point perfectly.

I have seen this for fact, and I am sure a lot of other people will tell you the same thing all over the world. You can take any given stone, and under different lighting, they look completely different. I don''t care weather it''s a diamond, or something else. You could have the most awesome looking stone in the world at high noon in downtown Bangkok. Take the same exact stone in your living room outside of New York City, and it won''t look the same. That''s a no brainer there.

That''s why when you go to test these things, you test it under a controlled light source that has been accepted. If someone looks at it and it doesn''t look right under certain lighting conditions, you know why. That''s another reason why stones aren''t graded for "appearance" as it''s a subjective term.

What appears to be good in the store isn''t going to always appear the same in your kitchen. Do you see what I mean? What appears to be good or bad is a matter of opinion on face value. What actualy is and what can actually be measured is another story.

 

[Serg]

Joe,

Do you really know Dave point?
1)Dave point: If the diamond A looks better than the diamond B in reasonable light scheme , The diamond A will looks better than the diamond B in any other reasonable light scheme. Dave , please correct me if I am wrong.
2) Now please answer : What is diamond best in first image? What is diamond best on second image?

It is not main issue of my example. My example is not silly.

 

[solange]

I have not seen the term Brilliant--Portugese Round--in any discussions here. What would one look for in a stone that is more brilliant because it has more facets in the pavillion? Is there a brand name or other term for such a round stone?

 

[jszweda]

Sergey...

I don''t think anyone is saying you''re point is silly. Don''t get us wrong here.

Dave''s point is that a given diamond will be the same grade in any light. The thing is, when you say grade, there is a specific meaning to that, and when you talk to someone like Dave who is a GG, someone like him or someone who knows something about diamonds will deem that term as a technical meaning.

Now if diamond A is better than diamond B by some criteria, if you are refering to the brilliance or luster, then yes. Diamond A would look better than diamond B under the same exact light. I understand that.

Now, if you really want to know which is better, based on just what appears to the naked eye, they all look the same. If you really want to know which one is best, I would have to look at the stones in person to give you my honest opinion. Keep in mind with me at least, better is a relative term.

One stone shaped different from the next doesn''t make a stone any better or worse. If one stone is a D color stone for example, does it make it better than a J colored stone? If you want something clearer, then the D is better. However, if you want something more white, the J colored stone would be better. Now, if the J colored stone is IF and the D colored stone is I2, which is better?

Better is a matter of opinion, and if you want my honest opinion, I don''t really care for the tone that I am seeing in those stones. Then again, there could be reasons with the lighting for that, the position of that, and whatever the camera does or fails to do can affect that too. As for which is a better quality, I can''t say either based soley on those pictures.

HTH

 

[jszweda]

Portuguesse round cuts are refered to as a brilliant round also. I don''t like that term because to me that doesn''t say if the stone is brilliant in luster and round, or if it refers to a specific style of cut.

If you want to tell if a stone is a Portuguesse round or brilliant round as it is often refered to as in diamonds, this is easy.

1. Flip the stone upside down (table face down).
2. Look at the pavillion.
3. There are several more facets on the bottom. They look diamond shaped instead of triagonal, and the pavillion has a more convex shape to it than a traditional round. The facets are also considerably smaller in area as compared to a single pavillion facet with the standard round. If the stone is set, look at the facets through a loupe from the table vantage point.
4. When you look at the stone, it has a starburst type of effect or a swirl in the luster. The back facets can give the appearance of a hurricane texture moving in a counter clockwise direction.

You don''t see that style of cut as often in a diamond solitare as you do a traditional round cut. It is a specialty cut, and it takes some skill to do it right. However, a "brilliant round" cut will have a distinct luster to it, and you can see that as you rotate it in the light.

 

[Garry H (Cut Nut)]

Date: 1/13/2006 9:53:11 AM
Author:Serg


Hi all,



Please look how a remarkable round stone (second from left) can be turned to ugly look after only one change in lighting conditions.



Who may say now that lighting can NOT change cut quality grade? That a good diamond will be better than a bad diamond under any lighting?



Out of these two lightings one is standard for consumers and the other one is standard gemological color and sometimes cut grading environment.



Exposure time was automatically choosed by camera. Human eyes are adopted to lighting similar way and percept this effect the same way.





Questions:


1) Which cut is better (round or princess)?

2) What we did with lighting?

3) Which type of lighting is similar with lab color environment grading?





Sergey and Yuri.

Oh this is hard Sergey!!! - i prefer the round because in at least 1 lighting type it excells - whereas in both lightings the princess never excells.
2. The top lighting has a lot of light - and the camera / viewer is far enough away to not make a lot of obstruction (is it a ring flash and a lot of white polystyrene light box?) the lower light looks like a color grading enviro with the single tube directly above the stones - but you have placed the stones so they are only getting a very low angle light - or maybe even the light is shining more on the pavilions?

3. the lower one

 

[strmrdr]

Date: 1/13/2006 5:53:28 PM
Author: jszweda
Portuguesse round cuts are refered to as a brilliant round also. I don''t like that term because to me that doesn''t say if the stone is brilliant in luster and round, or if it refers to a specific style of cut.

oh boy I dont know where to start....
First off Portuguesse round cut is a colored gemstone cut to enhance color it is not suited to diamonds.
A few are likely cut that way but they are total trash with very little spread per ct.

 

[strmrdr]

Date: 1/13/2006 5:45:35 PM
Author: jszweda
Sergey...
Dave''s point is that a given diamond will be the same grade in any light. The thing is, when you say grade, there is a specific meaning to that, and when you talk to someone like Dave who is a GG, someone like him or someone who knows something about diamonds will deem that term as a technical meaning.

Please click the link in his Sig and see who Serg is.
then maybe you will start to get a clue that this discussion is so far over your head you wouldnt get it if you had a rocket ship.

 

[strmrdr]

Date: 1/13/2006 11:07:40 AM
Author: jszweda




On the lighting, the best thing to do is to use what is known as darkroom illumination. Use 2 5500K flourescent lamps with a color refractive index of 91 or better

Tell me where I can get the finger mount version so I can have that lighting all the time.
Diamonds live in the real world with real world lighting conditions not under 2 color corrected lamps.

 

[strmrdr]

Date: 1/13/2006 5:37:53 PM
Author: solange
I have not seen the term Brilliant--Portugese Round--in any discussions here. What would one look for in a stone that is more brilliant because it has more facets in the pavillion? Is there a brand name or other term for such a round stone?

Please dont listen to jszweda unless you want to get totaly confused.
He dont have a clue and is giving you bad advice.

If anyone is wondering why Im jumping on him that is why.
Serg and Garry can take care of themselves but give very very bad advice to a member of my PS family and I will jump in.

 

[belle]

if the camera is set to adapt light the same way as the human eye, the first set up must be one that is conducive to directing light from the stones directly back to the viewer because this would effect the light accomodation of the eye making the background seem darker. i think the first view is that in which consumers use and the second is what graders use. from the pictures, it is possible that there was no change in the lighting itself, only the conditions.
obviously the large round in the first picture looks the brightest, which is what many consumers would count as ''the best''

 

[oldminer]

There is no question that the second round diamond in the first instance is very brilliant. It does not look so very special in the second lighting scenario. My eyes do see it that way. This diamond may not be the best cut diamond of the group, but under strong lighting it is very brilliant.

I am guessing that there would be more lighting than necessary to discriminate between the effectiveness of the cut in scenario #1 and possibly too little light to discriminate, at least with only our eyes, in scenario #2. To me "effectiveness of cut" equates to the creation of a beautiful looking diamond, a well cut stone.

Just like lowering the F stop in a camera lens too wide and allowing more llight to get to the film or the sensor, too much light makes for lack of discrimination, not better discrimination. One must use enough light to discriminate welll, yet not so much or too little which inhibits discrimination. My belief is that finding a balanced amount of light is critical to a correct standard lighting environment.

The larger problem I have seen over the past couple of years are that those who argue for different lighting models for cut grading are outside of the GIA and universally seen as unqualified to create any internationally standard environment. The arguments can go on forever, but who sees an outcome from this process of practical merit? I see the arguments perpetuating the status quo and the GIA taking those who simply go on blind faith being led astray.

 

[jszweda]

Strmrdr,

I disagree with you. The term Portuguesse is a technical term, and usually you find it in colored gem stones. However, the use of that cut in a diamond doesn''t mean that the diamond is of poor quality. I don''t know what you base that off of, but I have seen clean diamonds that are cut as that, and I assure you they were not of poor quality. I am not saying you personally haven''t, but I am telling you what I have seen.

Secondly, that cut is not used to enhance color for a colored stone. It may enhance the brilliance of the stone, but it doesn''t enhance the actual color as you put it. I have never heard of anyone using that particular cut to "enhance" the color of any stone.

Finally, I don''t think my advice is bad and I did click on the link for this guy''s signature. So he has a web site. Fine. He asked a question, and I am here to offer my opinion just like anyone else is entitled to. I also ask what he is refering to as different things have different meanings. And while in the real world you don''t run around with a set of lamps on your finger, that is the industry standard for grading diamonds. The discussion was about the grading of stones, and since lighting came up, I stated what I did.

I am also quite sure that you along with many others on here understand that sunlight is not a controlled source of lighting and can give a variant appearance on a given stone. That is also a real world thing, which is why there are certain standards to "grade" stones-and that is also subjective to the term grade.

I tend to views these things and discussions in technical terms. If someone means something other than the technical term I envision, then it need to be clarified as to what they mean.

 

[strmrdr]

jszweda just had to keep digging didnt ya.. pretty soon your going to hit China..
............
Portuguese Cut:
Read the post by Michael_E who is a very skilled gemstone cutter
https://www.pricescope.com/community/threads/portuguese-cut.10517/

"Having multiple rows of pavilion facets gains depth, thereby saving weight and it significantly enriches the color of light colored stones like aquamarine."

...........

have you heard of:
Helium?
DiamCalc?
MSU Gemological Center?
IDCC 2004

what do they have in common?
Serg

Cant seem to find his bio at the moment hmmmm

 

[jszweda]

Serg, my friend...

You have illustrated one of my points quite well here. If I may quote what your last post said..

"First off Portuguesse round cut is a colored gemstone cut to enhance color it is not suited to diamonds.
A few are likely cut that way but they are total trash with very little spread per ct. "

Now having said that,

https://www.pricescope.com/community/threads/portuguese-cut.10517/ "Having multiple rows of pavilion facets gains depth, thereby saving weight and it significantly enriches the color of light colored stones like aquamarine."

To enrich a color is one thing. To enhance it to me suggests something entirely different and has a technical meaning to it. Does that make sense to you?

 

[strmrdr]

Date: 1/13/2006 7:59:29 PM
Author: jszweda
Serg, my friend...

You have illustrated one of my points quite well here. If I may quote what your last post said..


''First off Portuguesse round cut is a colored gemstone cut to enhance color it is not suited to diamonds.

A few are likely cut that way but they are total trash with very little spread per ct. ''


Now having said that,


https://www.pricescope.com/community/threads/portuguese-cut.10517/ ''Having multiple rows of pavilion facets gains depth, thereby saving weight and it significantly enriches the color of light colored stones like aquamarine.''


To enrich a color is one thing. To enhance it to me suggests something entirely different and has a technical meaning to it. Does that make sense to you?

well this thread it trashed :{

serg didn''t say that I did.
Are you related to Bill Clinton?

looking up the definitions:

enrich == make better or improve in quality
enhance == make better or more attractive

what was your point again?

 

[jszweda]

I think you''re not understanding me for whatever reason, so all me to clarify where I am coming from. My point here is quite simple, and this will be my last reply to this thread. Enhanced versus enriched. Let me to give you a hypothetical scenario with something like a diamond.

Let''s assume that we have a given diamond, and while it may be a rather large diamond, let''s say there is some inclusion in it and/or I don''t like the symmetry of it for whatever reason.

I look at it, and I say, I don''t like this thing at all but I think it has some potential if I could work around this inclusion. So I take this diamond to a lapidary, and I explain to them if I could work around this one inclusion, recut the thing, I think I could have a lovely VVS2 stone. I might even ask them to do a Portuguesse re-cut on it.

Now, I will loose some weight on that stone, granted. When it''s done, I have a lot more symmetrical stone than before due to a better lapidary, and the inclusion is gone.

Now I am going to sell this stone (hypothetically). Per the industry standards and the way the diamond industry works, if I have simply cut the stone differently, have I enhanced it in any way? I might as a sales person say I have managed to acquire this stone with a particular cut as to enrich the brilliance of it. However, have I enhanced this stone in any way as in a treatment? Should I say that this stone has been clarity enhanced? If I didn''t, would that mean I commited some fraudulent act? Is the color of the stone going to change soley based on the cutting assuming there were no viens in it to begin with?

That...is my point.

 

[mdx]

Date: 1/13/2006 8:55:43 PM
Author: jszweda
I think you''re not understanding me for whatever reason, so all me to clarify where I am coming from. My point here is quite simple, and this will be my last reply to this thread. Enhanced versus enriched. Let me to give you a hypothetical scenario with something like a diamond.

Let''s assume that we have a given diamond, and while it may be a rather large diamond, let''s say there is some inclusion in it and/or I don''t like the symmetry of it for whatever reason.

I look at it, and I say, I don''t like this thing at all but I think it has some potential if I could work around this inclusion. So I take this diamond to a lapidary, and I explain to them if I could work around this one inclusion, recut the thing, I think I could have a lovely VVS2 stone. I might even ask them to do a Portuguesse re-cut on it.

Now, I will loose some weight on that stone, granted. When it''s done, I have a lot more symmetrical stone than before due to a better lapidary, and the inclusion is gone.

Now I am going to sell this stone (hypothetically). Per the industry standards and the way the diamond industry works, if I have simply cut the stone differently, have I enhanced it in any way? I might as a sales person say I have managed to acquire this stone with a particular cut as to enrich the brilliance of it. However, have I enhanced this stone in any way as in a treatment? Should I say that this stone has been clarity enhanced? If I didn''t, would that mean I commited some fraudulent act? Is the color of the stone going to change soley based on the cutting assuming there were no viens in it to begin with?

That...is my point.

Huh ????


Johan

 

[Serg]

Joe,


I am not GG, Stones in my example are not diamonds.
Please forget my example. This topic is not about money, this topic about big money.

I saw this example first time 1 week ago, And last week 50% times I am thinking only about this phenomena, reasons and consequences for:
Fancy color grading
DC
New GIA cut grading D-Z diamonds( Special thanks to Michael Cowing, due two fortuitousness I found new important mistake ( much more important than close up and gray tray)in GIA tests

My dream is joint research work on PS.

Michael, Dave, Garry, Belle, strmrdr, Valeria, Leonid and Other Please start work, do not lost your time.

Just imagine: You turn on light in standard light equipment and brightest diamond become to darkest diamond.

Belle, Thanks, please continue.

 

[Serg]

re:is it a ring flash and a lot of white polystyrene light box?)

Nothing. We did not do any special. We use two type standard light scheme.

1) First is similar to "Office type" with white walls and big windows with white textile jalousie. Stones is inside Magna color scope ( Eickhorst company) . Position viewer, stones, light are like in GIA DiamondDock Viewing Environment ( but distance between stones, background and light shorter. because Magna color scope has smaller height. BTW This phenomena strongly depends from such distance. Light in Greta color scope turn off

2) Second . Same + light turn on.