Diamond fire vs spectra colour

[Malha777]

Hi everyone,

I have a question as I tried to search up the forum but I haven’t find anything about it.

Do you guys have any pictures, videos or links showing the difference between a diamond showing lots of spectra colour and a diamond showing fire?

In particular I’m interested in those diamonds showing lots of rainbow colours when in indirect sunlight.

Does it happen more often when the diamond is colourless vs it has more yellow?

Does it just depend on the cut or is there a specific diamond quality that influences it?

thanks a lot in advance!


D colour, super ideal cut diamond in indirect sunlight.

 

[daisygrl]

H color, indirect sunlight.

 

[Malha777]

H color, indirect sun light.

I can see clear arrows, is it a H&A or ideal cut? so beautiful!

 

[daisygrl]

I can see clear arrows, is it a H&A or ideal cut? so beautiful!

Thank you. Super-ideal. CBI.

 

[OoohShiny]

What is 'spectra' colour?

Surely all colour in a diamond must be 'fire', by way of white light being split into rainbow dispersion fans by the cut of the diamond?

 

[headlight]

Color grade would have no effect. I would think that a significant number and/or placement of certain clarity characteristics could be a hindrances. This is an interesting topic because I had a stone previously that was poorly cut but it faired well in that environment.

 

[Malha777]

Color grade would have no effect. I would think that a significant number and/or placement of certain clarity characteristics could be a hindrances. This is an interesting topic because I had a stone previously that was poorly cut but it faired well in that environment.

I’ve seen stones that were not really cut to an ideal grade but still showing lots of rainbow colours in their body.
I’m still researching about this. I think that I can refer to this characteristic as “fire” as well, but not in a direct light environment.
All of your help is so appreciated!

 

[Malha777]

What is 'spectra' colour?

Surely all colour in a diamond must be 'fire', by way of white light being split into rainbow dispersion fans by the cut of the diamond?

Yeah probably it is just fire, but some stones at times have more colours appear in their body. Something to deal with “transparency”?

 

[Matthews1127]

G colored EC.
Indirect sunlight, at sunset.



OEC (Nancy) G-I color range.
Indirect sunlight, mid-day at the beach.


Vintage Cut Asschers by Yoram at GemConcepts. F-H color range.
Indirect Sunlight at sunset.

 

[yssie]

Color grade would have no effect.

Disagree with above statement - colour grade will def have an effect: Colour is the result of the material absorbing certain wavelengths, so those wavelengths will be missing from both fire/spectral return and dispersive return.



@Malha777 - Three resources I highly recommend - they'll likely answer all your questions and more:
1. http://www.gemology.ru/cut/english/grading1/fig4.htm (trace URL breadcrumbs for context)
2. http://www.gemology.ru/cut/english/rainbow/2.htm
3. https://www.gia.edu/doc/Winter-2009-Gems-Gemology-Diffraction-Gratings-Dispersion-Fire-Diamonds.pdf

 

[Malha777]

Disagree with above statement - colour grade will def have an effect: Colour is the result of the material absorbing certain wavelengths, so those wavelengths will be missing from both fire/spectral return and dispersive return.



@Malha777 - Three resources I highly recommend - they'll likely answer all your questions and more:
1. http://www.gemology.ru/cut/english/grading1/fig4.htm (trace URL breadcrumbs for context)
2. http://www.gemology.ru/cut/english/rainbow/2.htm
3. https://www.gia.edu/doc/Winter-2009-Gems-Gemology-Diffraction-Gratings-Dispersion-Fire-Diamonds.pdf

Very interesting, thanks. I heard about those plasma etched diamonds and here is a video showing one

Very cool isn’t it? Looks like a moissanite at this point

Dancing diamond

 

[KLE]

Very interesting, thanks. I heard about those plasma etched diamonds and here is a video showing one

Very cool isn’t it? Looks like a moissanite at this point

Dancing diamond

I saw those diamonds in person at a local jewelry store. It was pretty eye catching and the rainbows were stunning. But I made a comment that it just didn’t look like a diamond - and the sales girl kind of made it seem like that was a common thought with others as well.

 

[headlight]

Disagree with above statement - colour grade will def have an effect: Colour is the result of the material absorbing certain wavelengths, so those wavelengths will be missing from both fire/spectral return and dispersive return.



@Malha777 - Three resources I highly recommend - they'll likely answer all your questions and more:
1. http://www.gemology.ru/cut/english/grading1/fig4.htm (trace URL breadcrumbs for context)
2. http://www.gemology.ru/cut/english/rainbow/2.htm
3. https://www.gia.edu/doc/Winter-2009-Gems-Gemology-Diffraction-Gratings-Dispersion-Fire-Diamonds.pdf

Hi @yssie ~ so that I understand this... a diamond with a lower color is going to be less of a performer in indirect sunlight than a more colorless one? Thank you!

 

[headlight]

I saw those diamonds in person at a local jewelry store. It was pretty eye catching and the rainbows were stunning. But I made a comment that it just didn’t look like a diamond - and the sales girl kind of made it seem like that was a common thought with others as well.

I’ve seen them, as well - The colors don’t look natural, IMO. The group mentioned in the article @yssie posted tried to market them as Fire Polish but they ran into issues with regard to rights over the technology, as I recall.

 

[yssie]

Hi @yssie ~ so that I understand this... a diamond with a lower color is going to be less of a performer in indirect sunlight than a more colorless one? Thank you!

A lower-coloured (more tinted) diamond looks coloured because the material is absorbing a certain amount of inbound energy of a given wavelength. What colour (hue, to be precise) it looks depends on what wavelengths the material is absorbing, and how saturated it looks depends on how much energy the material is absorbing.

A colourless diamond can return at most the full spectrum that is inbound. This is why in yellow lights even a D diamond looks yellow - it can only work with its lighting environment. A tinted diamond of same size and faceting will return some portion of the inbound spectrum (this is everything that’s left after the material has absorbed whatever wavelengths it’s going to).

A colourless diamond can return at most some portion of the inbound energy (not all of it - a mirror would return all of it). Assuming identical size and faceting, a tinted diamond absorbs more of this inbound energy, and so outputs less of it. Higher-energy output = “brighter stone”.

A diamond with body colour is objectively incapable of looking as bright as an otherwise-identical colourless diamond in any lighting environment.

I highlight identical size and faceting because the specific paths that inbound light takes as it bounces inside the stone and returns out of the stone is determined by facet size and pattern. Changes to these light paths can hugely impact quantity of energy absorption (won’t change which wavelengths are absorbed, of course).

How we perceive this is also interesting - we’re wired to equate “bright” with “big”, visually. A brighter object looks bigger than a darker object of same shape and size. A brighter diamond will look bigger than a more tinted diamond of same size and faceting. Is it actually visible? To me, yes: I’ve held my 2.7ct J next to a colourless stone with eerily similar proportions and the colourless stone looked bigger to me, no question. Others might not have seen a difference.

What does this mean in terms of “performance”? That’s much more difficult - performance inherently encompasses both (objective) quantity and (subjective) quality. If we just wanted to maximize quantity of light return we’d all wear mirrors on our fingers, as @Rockdiamond often says. If “more performant” means “more aesthetically pleasing”, then its impossible to ignore the fact that people just like different things! I was perfectly happy to give that bigger, brighter 2.76 E back - I like my J better. Partly because my name starts with J, nothing technical about that

 

[daisygrl]

I’m going to try to answer very carefully and precisely so I don’t trip over any presumptions -

A lower-coloured (more tinted) diamond looks colour because the material is absorbing a certain amount of inbound energy of a given wavelength. What colour (hue, to be precise) it looks depends on what wavelengths the material is absorbing, and how saturated it looks depends on how much energy the material is absorbing.

A colourless diamond can return at most the full spectrum that is inbound. This is why in yellow lights even a D diamond looks yellow - it can only work with its lighting environment. A tinted diamond will return some portion of the inbound spectrum (this is everything that’s left after the material has absorbed whatever wavelengths it’s going to).

A colourless diamond can return at most some portion of the inbound energy (not all of it - a mirror would return all of it). Assuming identical size and faceting, a tinted diamond absorbs more of this inbound energy, and so outputs less of it. Higher-energy output = “brighter stone”.

A diamond with body colour is objectively incapable of looking as bright as an otherwise-identical colourless diamond in any lighting environment.

How we perceive this is also interesting - we’re wired to equate “bright” with “big”, visually. A brighter object looks bigger than a darker object of same shape and size. A brighter diamond will look bigger than a more tinted diamond of same size and faceting. Is it actually visible? To me, yes: I’ve held my 2.7ct J next to a 2.76 E with eerily similar proportions and the E looked bigger to me, no question. Others might not have seen a difference.

What does this mean in terms of “performance”? That’s much more difficult - performance inherently encompasses both (objective) quantity and (subjective) quality. If we wanted to maximize quantity of light return we’d wear mirrors on our fingers, as @Rockdiamond often says. If “more performant” means “more aesthetically pleasing”, then its impossible to ignore the fact that people just like different things. I was perfectly happy to give that bigger, brighter 2.76 E back - I like my J better. Partly because my name starts with J, nothing technical about that

Helpful and clear explanation.

Btw, my name starts with E so I am more than willing to keep an eye on that 2.76 E of yours.

 

[headlight]

A lower-coloured (more tinted) diamond looks coloured because the material is absorbing a certain amount of inbound energy of a given wavelength. What colour (hue, to be precise) it looks depends on what wavelengths the material is absorbing, and how saturated it looks depends on how much energy the material is absorbing.

A colourless diamond can return at most the full spectrum that is inbound. This is why in yellow lights even a D diamond looks yellow - it can only work with its lighting environment. A tinted diamond of same size and faceting will return some portion of the inbound spectrum (this is everything that’s left after the material has absorbed whatever wavelengths it’s going to).

A colourless diamond can return at most some portion of the inbound energy (not all of it - a mirror would return all of it). Assuming identical size and faceting, a tinted diamond absorbs more of this inbound energy, and so outputs less of it. Higher-energy output = “brighter stone”.

A diamond with body colour is objectively incapable of looking as bright as an otherwise-identical colourless diamond in any lighting environment.

I highlight identical size and faceting because the specific paths that inbound light takes as it bounces inside the stone and returns out of the stone is determined by facet size and pattern. Changes to these light paths can hugely impact quantity of energy absorption (won’t change which wavelengths are absorbed, of course).

How we perceive this is also interesting - we’re wired to equate “bright” with “big”, visually. A brighter object looks bigger than a darker object of same shape and size. A brighter diamond will look bigger than a more tinted diamond of same size and faceting. Is it actually visible? To me, yes: I’ve held my 2.7ct J next to a colourless stone with eerily similar proportions and the colourless stone looked bigger to me, no question. Others might not have seen a difference.

What does this mean in terms of “performance”? That’s much more difficult - performance inherently encompasses both (objective) quantity and (subjective) quality. If we just wanted to maximize quantity of light return we’d all wear mirrors on our fingers, as @Rockdiamond often says. If “more performant” means “more aesthetically pleasing”, then its impossible to ignore the fact that people just like different things! I was perfectly happy to give that bigger, brighter 2.76 E back - I like my J better. Partly because my name starts with J, nothing technical about that

Really interesting - thanks for giving your time to this. Thought provoking and brings to mind many more observations and questions!

 

[Garry H (Cut Nut)]

Do you guys have any pictures, videos or links showing the difference between a diamond showing lots of spectra colour and a diamond showing fire?
In particular I’m interested in those diamonds showing lots of rainbow colours when in indirect sunlight.
How do diamonds show rainbows? Do you mean a ray of light breaking up like dark side of the moon album cover?
The fire flashes in a diamond are mostly blue with some red orange and rarely yelllow. Green is very rare (can be explained why with more time). Diamonds that are yellow will likely have less blue flashes.
Does it happen more often when the diamond is colourless vs it has more yellow?

Does it just depend on the cut or is there a specific diamond quality that influences it?

thanks a lot in advance!


D colour, super ideal cut diamond in indirect sunlight.

 

[Karl_K]

Disagree with above statement - colour grade will def have an effect: Colour is the result of the material absorbing certain wavelengths, so those wavelengths will be missing from both fire/spectral return and dispersive return.



@Malha777 - Three resources I highly recommend - they'll likely answer all your questions and more:
1. http://www.gemology.ru/cut/english/grading1/fig4.htm (trace URL breadcrumbs for context)
2. http://www.gemology.ru/cut/english/rainbow/2.htm
3. https://www.gia.edu/doc/Winter-2009-Gems-Gemology-Diffraction-Gratings-Dispersion-Fire-Diamonds.pdf

While technically true in j and up its such a small portion that it gets overblown at times.
Compare a D to a s-t brown or a fly sure its true and visible and even obvious but in j and up not so much.

 

[headlight]

While technically true in j and up its such a small portion that it gets overblown at times.
Compare a D to a s-t brown or a fly sure its true and visible and even obvious but in j and up not so much.

Okay, so I’m not totally off!... I was just going on personal observation.

 

[Karl_K]

Okay, so I’m not totally off!... I was just going on personal observation.

Your good.
I was just putting it in perspective.

 

[Texas Leaguer]

Great topic. Fire is surely the most magical (and illusive) property of a gem diamond.

Facet design and execution are both critical to produce the prismatic effect of fire. There is a tradeoff in design between optimal amounts of fire and the other light performance factors of brightness and scintillation. Some facet arrangements maximize fire at the expense of brightness. Some designs favor brightness, while others find the optimal balance.

But even if the design is great, if the faceting precision is poor, the intended mix of effects will suffer. Light must be propagated thru the diamond efficiently and accurately, in order to be refracted and exit the crown, and in the case of fire, produce a fan of spectral colors large enough to be clipped by the pupil of an observer and result in the experience of a colored sparkle.

As such, not only cutting factors impact what the diamond can produce in the way of visual effects, but color and clarity factors do too. That is why some diamond enthusiasts not only want precision cut diamonds, but also colorless, microscopically clean diamonds as well.

Some interesting images and videos here:

Diamond Fire – What Exactly Is It? | Whiteflash

Diamond fire is the specific optical effect of colored sparkles as light is broken into rainbow colors due to refraction. Learn how cut is the secret to fire.

www.whiteflash.com

 

[yssie]

While technically true in j and up its such a small portion that it gets overblown at times.
Compare a D to a s-t brown or a fly sure its true and visible and even obvious but in j and up not so much.

Depends on the person. I’ve seen this difference btwn my J (GIA and AGS) and a GIA E... Agree though, not a reason to not get a J (or an S-T brown for that matter)

 

[John P]

In particular I’m interested in those diamonds showing lots of rainbow colours when in indirect sunlight.

Does it happen more often when the diamond is colourless vs it has more yellow?
Does it just depend on the cut or is there a specific diamond quality that influences it?

In terms of conversation and definitions, I'd add this:

• Dispersion occurs physically, within the diamond.
• Absorption (when relevant) occurs physically, within the diamond.
• "Seeing" Fire occurs physiologically, at the human eye.

So what you "see" isn't just about the illumination scenario and cut-geometry (or absorption spectroscopy - which is another can of gummis). It's also about your pupil constriction or dilation, your specific physiology - people see color differently - whether you're wearing glasses, etc.

I wrote an article for IGI on the topic a couple of months ago, with graphics and photos, in case it's interesting.

Linked here: Dispersion & Fire are not the same thing.

 

[headlight]

Great topic. Fire is surely the most magical (and illusive) property of a gem diamond.

Facet design and execution are both critical to produce the prismatic effect of fire. There is a tradeoff in design between optimal amounts of fire and the other light performance factors of brightness and scintillation. Some facet arrangements maximize fire at the expense of brightness. Some designs favor brightness, while others find the optimal balance.

But even if the design is great, if the faceting precision is poor, the intended mix of effects will suffer. Light must be propagated thru the diamond efficiently and accurately, in order to be refracted and exit the crown, and in the case of fire, produce a fan of spectral colors large enough to be clipped by the pupil of an observer and result in the experience of a colored sparkle.

As such, not only cutting factors impact what the diamond can produce in the way of visual effects, but color and clarity factors do too. That is why some diamond enthusiasts not only want precision cut diamonds, but also colorless, microscopically clean diamonds as well.

Some interesting images and videos here:

Diamond Fire – What Exactly Is It? | Whiteflash

Diamond fire is the specific optical effect of colored sparkles as light is broken into rainbow colors due to refraction. Learn how cut is the secret to fire.

www.whiteflash.com

This is fabulous - thank you! On that note (sort of), did you see the GIA Instagram post yesterday:

 

[headlight]

@Texas Leaguer
P.S. I don’t expect you to comment, I just found it to be an “interesting” post

 

[John P]

Some interesting images and videos here:

Diamond Fire – What Exactly Is It? | Whiteflash

Diamond fire is the specific optical effect of colored sparkles as light is broken into rainbow colors due to refraction. Learn how cut is the secret to fire.

www.whiteflash.com

Shout out to @diagem for the epic photo in your article. I've had and used it for a long time. It's tremendous in terms of training.

 

[Texas Leaguer]

Shout out to @diagem for the epic photo in your article. I've had and used it for a long time. It's tremendous in terms of training.

Agree. Seeing Yoram's photo for the first time was an ah ha! moment for me. For some reason I could not wrap my head around written explanation of pupil 'clipping' in the AGS research articles. As they say a picture is worth a 1,000 words. Sometimes worth more!

 

[Garry H (Cut Nut)]

The absorption of some blue causing yellow has very little effect on the blue flashes. This is approaching a fancy yellow grade done in DiamCalc

 

[Garry H (Cut Nut)]

In terms of conversation and definitions, I'd add this:

• Dispersion occurs physically, within the diamond.
• Absorption (when relevant) occurs physically, within the diamond.
• "Seeing" Fire occurs physiologically, at the human eye.

So what you "see" isn't just about the illumination scenario and cut-geometry (or absorption spectroscopy - which is another can of gummis). It's also about your pupil constriction or dilation, your specific physiology - people see color differently - whether you're wearing glasses, etc.

I wrote an article for IGI on the topic a couple of months ago, with graphics and photos, in case it's interesting.

Linked here: Dispersion & Fire are not the same thing.

Great article John. But note that the green is almost totally absent in all your real life photos. You might need to explain that.