When do we get fire? Why is it sometimes pastel?

[Dancing Fire]

[quote="Rockdiamond]

Serg- I have never purchased diamonds on the basis of "fire". Looking through many photos, I do notice the the effect has occurred in pretty much every shape of stones. In general, larger facets seem to present more opportunities for fire. Cuts like Emerald and OMB have some large facets, so there's a lot of opportunity for fire.I'm sure your point about size will hold true- but the camera can pick up fire flashes on very small facets as well.

David
What good is a diamond w/o "fire"..? may as well wear a piece of glass since glass is a lot cheaper.

Can you actually see fire in your diamonds DF?
Not speaking of pictures of them, but actually looking at them

[/quote][/quote]
David, I don't get it... You are the only person on earth whom does not love a sparkling diamond... [/quote][/quote][/quote][/quote]


DF- I did not notice the answer to my question. Have you seen what we are referring to ( fire= dispersion of color) with your naked eyes?
To remind you- I began learning about diamonds and was trained by Harry Winston to assess diamonds for cut, color, and clarity- in fact, I'm looking forward to the 40th anniversary of my start date at Winston in about 10 days. The amount I've leaned and seen over these 40 years is astounding.
I've always LOVED well cut stones, and have been lucky enough to see countless sparkly diamonds- even luckier to have owned thousands of amazing, sparkling diamonds.[/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote]Isn't this consider as fire?..

 

[Rockdiamond]

Here are a couple of pics that show a variety of colored flashes. Some are reflections and some are actual dispersion.



I am always especially intrigued by looking at the fire projected onto the surface beneath the diamond. You can see various saturation levels (some pastels). The individual colors really pop against the dark background. I think that is also an illustration of why you need the proper contrast in the stone to exhibit fire.






Let's call this my attempt to decorate this thread with festive lights. Happy Holidays Everyone !

Generally speaking, when "fire" is reffered to here, it's a prism effect- like this DF

 

[Texas Leaguer]

[quote="Rockdiamond]

Serg- I have never purchased diamonds on the basis of "fire". Looking through many photos, I do notice the the effect has occurred in pretty much every shape of stones. In general, larger facets seem to present more opportunities for fire. Cuts like Emerald and OMB have some large facets, so there's a lot of opportunity for fire.I'm sure your point about size will hold true- but the camera can pick up fire flashes on very small facets as well.

David
What good is a diamond w/o "fire"..? may as well wear a piece of glass since glass is a lot cheaper.

Can you actually see fire in your diamonds DF?
Not speaking of pictures of them, but actually looking at them

[/quote][/quote]
David, I don't get it... You are the only person on earth whom does not love a sparkling diamond... [/quote][/quote][/quote][/quote]


DF- I did not notice the answer to my question. Have you seen what we are referring to ( fire= dispersion of color) with your naked eyes?
To remind you- I began learning about diamonds and was trained by Harry Winston to assess diamonds for cut, color, and clarity- in fact, I'm looking forward to the 40th anniversary of my start date at Winston in about 10 days. The amount I've leaned and seen over these 40 years is astounding.
I've always LOVED well cut stones, and have been lucky enough to see countless sparkly diamonds- even luckier to have owned thousands of amazing, sparkling diamonds.[/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote][/quote]
David,
I am curious about the nature of your question to DF. It almost seems like you are questioning the premise that fire can be seen with the naked eye.

It is not just something purely theoretical or only captured with a camera. Of course it takes a diamond cut such that it has good fire potential along with the right lighting circumstances to observe it. (Without fire potential it can never be observed- with good fire potential it can be observed any time the conditions are right)

It is like a rainbow after a rain shower. Not every shower is followed by one - the situation has to be right. But when you do see it it is special.

Diamond is a material with high dispersion and therefore the potential to produce good fire. Other materials have even better potential to produce fire, but do not have the other attributes that make diamond so desirable.

Most people feel that a well cut diamond is one that has the best combination of brightness, fire and contrast. And it is possible to quantify those attributes scientifically because they all result from the physics of light and can be calculated mathematically.

 

[Dancing Fire]

[quote="Texas Leaguer|

David,
I am curious about the nature of your question to DF. It almost seems like you are questioning the premise that fire can be seen with the naked eye.

[/quote]


Yeah, I am ...

 

[Rockdiamond]

Hi Bryan,
The easiest way to "observe" fire is when the diamond throws prisms on the wall- which you alluded to in your post.
Seeing the prism through the table is not something I have noticed- unless I was looking through a loupe and the conditions were exactly correct.
If I hold a diamond super close to my eye I can observe repeatable prism effect. But I would not generally try to position the diamond to make a prism.
However I have easily and often observed plenty of characteristics in diamonds that a lot of people would call fire.
As you also pointed out Bryan- "fire" has it's own meaning in this discussion.

You mentioned that "most" people prefer a certain combination of charachteristics.
I have found that there's simply far too many options in diamond cut- as well as educated opinions about them to make any sort of generalization which combination is "best"- much less use it to claim a scientific basis for what people prefer.

 

[Rockdiamond]

Question Bryan- or anyone else:
Is it easier to see "fire" in a large crystal- like on a chandelier, or on a 2ct 0 cut grade RBC?

I mean if prisms are what you're aiming for.....

 

[Karl_K]

Hi Bryan,

Seeing the prism through the table is not something I have noticed- unless I was looking through a loupe and the conditions were exactly correct.

David,
I have been telling you for years to get out of your office and actually look at diamonds.
You examine diamonds not look at them.

 

[Rockdiamond]

Just curious Karl, what is your favorite place or type of lighting to see fire?
If you never noticed, my avatar- cut by Yoram, actually exhibits fire in the table and on the crown in spite of such a deep color. Which is another aspect never touched- how color affects fire.
I notice it all the time in pictures.

 

[Karl_K]

Just curious Karl, what is your favorite place or type of lighting to see fire?

outside under a tree on a clear day
warehouse type store with high ceilings with florescent lights up high.
some elevators with the small spot lighting
bathrooms with the smaller lights in a row over and around the mirror.
my kitchen with the new ceiling fan with 3 small bulb lights sets them off.
It is similar to this one:

 

[Rockdiamond]

Karl- do you know the height of my office ceiling, and illumination type?
We're taking 14 foot ceilings, with, yes you guessed it, fluorescent lighting.

I have always advised consumers to look at diamonds under a variety of lighting conditions. I always do before I pull the trigger and buy a diamond.
Now I'll suggest they head over to your place, for fire testing

 

[Karl_K]

Karl- do you know the height of my office ceiling, and illumination type?
We're taking 14 foot ceilings, with, yes you guessed it, fluorescent lighting.

At 14 feet florescent tubes with diffuser panels are still a large light source which will produce mostly brightness.

 

[Rockdiamond]

All right- then I'll need to head to your place and check out this kitchen light

 

[Serg]

Just curious Karl, what is your favorite place or type of lighting to see fire?
If you never noticed, my avatar- cut by Yoram, actually exhibits fire in the table and on the crown in spite of such a deep color. Which is another aspect never touched- how color affects fire.
I notice it all the time in pictures.

David, It is not good example for Fire. at least its not looks as Fire specially on Crown( it could be dispersion instead absorption , but it does not look as fire. it looks as absorption).

I asked you several time in previous discussions about your Fire definition. You never defined it. Sometimes you mixed Fire and Scintillation.

Did Harry Winston learn you to see Fire in diamonds 40 years ago ? may be you learned astounding about diamonds in last 40 years , but seems you would to learn a lot about diamond performance yet.

 

[Texas Leaguer]

Just curious Karl, what is your favorite place or type of lighting to see fire?

outside under a tree on a clear day
warehouse type store with high ceilings with florescent lights up high.
some elevators with the small spot lighting
bathrooms with the smaller lights in a row over and around the mirror.
my kitchen with the new ceiling fan with 3 small bulb lights sets them off.
It is similar to this one:

Agree. Those are all scenarios that can facilitate the observation of fire. In some cases it will cause the fire to jump dramatically.

But I have found that I can observe fire in most lighting situations if I am specifically looking for it. In my office I have high quality full spectrum fluoro tubes behind diffusers on the ceiling and a full spectrum fluoro table lamp. This lighting environment favors the observation brightness and accurate color. However, I can still see some fire by looking carefully for it. (I am looking primarily at precision cut rounds).

I recently took a video in my back yard of a 1.00 ct set in a half bezel ring with multiple small side diamonds. It was a clear morning. Background was darkish (green plants), ring was in direct sun. I was between 15 to 25 feet away. The overall lighting was bright, so I assume my pupils (and the aperture of the camera) were contracted. What I saw with my eyes was pretty dramatic and is faithfully represented on the video.
Not sure if youtube videos are allowed on the system but here is the short clip. (You should put the playback setting on HD)
https://www.youtube.com/watch?v=8setq7ebHww

You will notice that the most fire (biggest flashes of pure color) come from the center stone, but you can see some color sparks coming from the little side stones as well.

 

[Rockdiamond]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

 

[Serg]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

Dave , not really. Diamond Performance is not just opinion , it is objective. Taste is opinion. we would have different Taste of Fire-Brilliancy balance, but it does not change Diamond performance which is objective .
I highly respect opinion based on experience , I would not respect prejudice and ignorance based on authority and references.

 

[Texas Leaguer]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

David, I have no idea what you mean when you say "the definition of fire in the narrow purpose of this discussion". Gem fire is an optical property that was defined a century ago.

This line is from Tolkowsky's book: What we call white light is made up of a variety of different colours which produce white by their superposition. It is to the decomposition of white light into its components that are due a variety of beautiful phenomena like the rainbow or the colours of the soap bubble -- and, it may be added, the " fire " of a diamond.

 

[Serg]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

David, I have no idea what you mean when you say "the definition of fire in the narrow purpose of this discussion". Gem fire is an optical property that was defined a century ago.

This line is from Tolkowsky's book: What we call white light is made up of a variety of different colours which produce white by their superposition. It is to the decomposition of white light into its components that are due a variety of beautiful phenomena like the rainbow or the colours of the soap bubble -- and, it may be added, the " fire " of a diamond.

Bryan,
why do you believe in Such Fire definitions? just because it is from Tolkowsky, GIA, AGS?
Is Diamond Fire just dispersion? How is about flash sizes, duration, distribution ?
Dispersion is reason of Fire ( one of many reasons) , but it is not that we observe as Fire in diamonds.
when you see rainbow on soap bubble,do you see( think about) Fire( fire as in diamonds)?. what is difference between rainbow on soap bubble and Fire in diamonds?

 

[Rockdiamond]

Bryan– Given that English is your first language, I have no idea why you cannot understand what I said. If you ask 100 people on the street what the word fire means how many of them would describe the effect we talking about? This is a very limited discussion.
If you asked 100 diamond cutters, a lot of them would not know what you're talking about when you say "fire".

Serg- performance as defined by how a diamond behaves under a controlled environment may be objective. What that data means in the real world is very much opinion.
Therefore, using the term performance as an objective term is often misleading to people reading.

 

[Karl_K]

All right- then I'll need to head to your place and check out this kitchen light

Anytime, that would be fun.
I will even provide dinner.

 

[Texas Leaguer]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

David, I have no idea what you mean when you say "the definition of fire in the narrow purpose of this discussion". Gem fire is an optical property that was defined a century ago.

This line is from Tolkowsky's book: What we call white light is made up of a variety of different colours which produce white by their superposition. It is to the decomposition of white light into its components that are due a variety of beautiful phenomena like the rainbow or the colours of the soap bubble -- and, it may be added, the " fire " of a diamond.

Bryan,
why do you believe in Such Fire definitions? just because it is from Tolkowsky, GIA, AGS?
Is Diamond Fire just dispersion? How is about flash sizes, duration, distribution ?
Dispersion is reason of Fire ( one of many reasons) , but it is not that we observe as Fire in diamonds.
when you see rainbow on soap bubble,do you see( think about) Fire( fire as in diamonds)?. what is difference between rainbow on soap bubble and Fire in diamonds?

Serg,
The Tolkowsky quote was just to emphasize that people who study diamonds have been familiar with the concept of fire for generations. The fact that fire is one of the key beauty aspects of diamonds is not new. It is not an obscure theoretical concept that only a few physics geeks talk about or that can only be seen as projections in still pictures. Real people see this effect in real life and it is one of the reasons human beings have come to love diamonds.

Fire is not dispersion, but it depends on it. A rainbow on a soap bubble is caused by diffraction (a different mechanism), but the result is dispersion of white light into its component wavelengths (colors). I believe Tolkowsky's comment was only meant to provide a visual to his readers to describe phenomenon he was discussing.

I don't claim to be a physicist or a mathematician. My point is that unless those of us involved in the conversation are talking about the same property, a meaningful discussion is impossible. If someone is using the term fire but talking about scintillation it's a waste of everyone's time.

 

[Karl_K]

The dark color of the diamond make it very interesting and different then it would look in a white diamond.

Yes colored diamonds produce fire, there is no question that it does.
If you use the simplest definition as just colored light it does all the time.
However it does also split light like any other diamond.
However how do you separate it from tinted brightness which can be different shades or even colors from different length light paths?
I would call it fire when it is a different color than the diamond body and its modifiers.
It is very complex again.

 

[Texas Leaguer]

The dark color of the diamond make it very interesting and different then it would look in a white diamond.

Yes colored diamonds produce fire, there is no question that it does.
If you use the simplest definition as just colored light it does all the time.
However it does also split light like any other diamond.
However how do you separate it from tinted brightness which can be different shades or even colors from different length light paths?
I would call it fire when it is a different color than the diamond body and its modifiers.
It is very complex again.

Intuitively, there seems to me to be a significant difference between the light we perceive as body color and the projected, clipped bands of dispersed white light we perceive as fire. However, don't expect me to prove it!

My instincts tell me a logical explanation exists.

 

[Texas Leaguer]

By the way, if you want to see fire in a deep yellow gemstone check out sphalerite next time you are at a gem show. It has three times the dispersion of diamond. Unfortunately, it is very soft and not commonly used in jewelry.

Sorry for the tangent. I spent the first part of my career in the colored gemstone side of the business and it is always there tugging at me!

 

[Dancing Fire]

Serg- yes I understand the definition of fire in the narrow purpose of this discussion. And I answered that question earlier to you. No, there was no discussion of fire at Harry Winston 40 years ago. I have other pictures of the stone in my avatar that clearly demonstrate fire. The dark color of the diamond make it very interesting and different then it would look in a white diamond. You may also have something to learn about performance. I know that I still have more to learn after the amount of time I have spent – everyone can learn if they have an open mind.
Please can we respect each other in these discussions? I am not trying to insult you or anyone else.
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.

IMO, "performance" is seeing lots of fireworks from a diamond not someone's opinion...

 

[Serg]

Fire is the simultaneous (local) contrast of colour that is observed in a diamond.
The contrast of this coloured image depends on surrounding areas and on the duration
of a coloured flash.

 

[Serg]

Bryan– Given that English is your first language, I have no idea why you cannot understand what I said. If you ask 100 people on the street what the word fire means how many of them would describe the effect we talking about? This is a very limited discussion.
If you asked 100 diamond cutters, a lot of them would not know what you're talking about when you say "fire".

Serg- performance as defined by how a diamond behaves under a controlled environment may be objective. What that data means in the real world is very much opinion.
Therefore, using the term performance as an objective term is often misleading to people reading.

{quote}
I know English is not your first language, but when we speak of "performance " in relation to diamonds is only someone's opinion.
{quote}


David, Please check "Performance" word definitions. They are not from me. I hope Oxford and Cambridge dictionaries had been wrote by native speakers .

"performance noun (ACTIVITY)

B2 [C or U] how well a person, machine, etc. does a piece of work or an activity:
Some athletes take drugs to improve their performance.
High-performance cars (= those that are fast, powerful, and easy to control) are the most expensive."
http://dictionary.cambridge.org/dictionary/british/performance


"performance |pəˈfɔːm(ə)ns|
noun
1 an act of presenting a play, concert, or other form of entertainment: Don Giovanni had its first performance in 1787.
• an act of performing a dramatic role, song, or piece of music: Bailey gives a sound performance as the doctor.
• informal, chiefly Brit.a display of exaggerated behaviour or a process involving a great deal of unnecessary time and effort; a fuss: he stopped to fasten his shoelace and seemed to be making quite a performance of it.
2 [ mass noun ] the action or process of performing a task or function: the continual performance of a single task reduces a man to the level of a machine.
• a task or operation seen in terms of how successfully it is performed: pay increases are now being linked more closely to performance | [ count noun ] : it was a tremendous all-round performance by Wigan.
• the capabilities of a machine, product, or vehicle: the hardware is put through tests which assess the performance of the processor | [ as modifier ] : a performance car.
• (also linguistic performance)Linguistics an individual's use of a language, i.e. what a speaker actually says, including hesitations, false starts, and errors. Often contrasted with competence."

it is from Oxford dictionary( from my Apple notebook)

 

[Garry H (Cut Nut)]

Just curious Karl, what is your favorite place or type of lighting to see fire?
If you never noticed, my avatar- cut by Yoram, actually exhibits fire in the table and on the crown in spite of such a deep color. Which is another aspect never touched- how color affects fire.
I notice it all the time in pictures.

My favourite place to see fire is under the huge plane (plain) tree beside the shop on a cloudy but bright day.
The spaces between the leaves create thousands of tiny pin points of light and diamond dance. In this case a better cut definitely produces more fire.
I am on a trip at present and only catching up with this, but David I believe you read the article that Sergey, Yuri, Janak and I wrote for the Australian Gemmologist? http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf There are sections and definitions of fire.

If not- surely you read the short summary in Rapaport magazine a few months ago. http://www.rapnet.com/News/NewsItem...IssueID=0&ArticleTitle=Vision+Impacts+Sparkle

Fire is like BHP, or torque, or standing 1/4 mile time. It can be measured, which is exactly what Sergey's team of developers are working on using ViBox as the capture device. This is also importantly done with the stereo capture system - because as you should aall do to test it - see how many flashes you see with one eye vs with two. Most cuts give nearly twice as many with two eyes because the direction of viewing means you see fire from different light sources. Occasionally where fire should be the other eye sees a really bright source from the same virtual facet and that swamps the fire flash and we percieve only the white flash.

DF - that green flash is very rare and very hard to see - amaxing photo!

 

[Dancing Fire]

[quote="Garry H (Cut Nut)|

DF - that green flash is very rare and very hard to see - amaxing photo![/quote]



Garry...Why is the green flash rare?..

 

[Garry H (Cut Nut)]

[quote="Garry H (Cut Nut)|

DF - that green flash is very rare and very hard to see - amaxing photo!

Garry...Why is the green flash rare?.. [/quote]
Usually that part of the flash turns white/bright
See figure 3.5 in this article DF, and you will understtand, then try some real life experiments with a steady hand and few good for fire point lightsources.
http://www.gem.org.au/ckfinder/userfiles/files/GAA_Journal_V25_No3_web2(1).pdf

(David will not be able to do this in his office)