Brilliance, Fire, Scintillation, what are correct definitions?
- Thread starter Paul-Antwerp
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Dispersion is only one part of what causes fire.
If you were to think of it as an equation dispersion would only be one factor of many different factors that would calculate fire.
http://en.wikipedia.org/wiki/Dispersion_%28optics%29
In the technical terminology of gemology, dispersion is the difference in the refractive index of a material at the B and G Fraunhofer wavelengths of 686.7 nm and 430.8 nm and is meant to express the degree to which a prism cut from the gemstone shows "fire", or color. Dispersion is a material property. Fire depends on the dispersion, the cut angles, the lighting environment, the refractive index, and the viewer.
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Here is a defintion of Dispersion in a diamond provided by a retail jeweler's website which is well written:
Dispersion
Arranged around the table facet on the crown are several smaller facets (bezel and star facets) angled downward at varying degrees. These facets, and the angles at which they are cut, have been skillfully designed to break up white light as it hits the surface, separating it into its component spectral colors (for example, red, blue and green). This effect, which appears as a play of small flashes of color across the surface of the diamond as it is tilted, is what we refer to as the diamond's dispersion (also called "fire"). This play of color should not be confused with a diamond's natural body color (normally white, though sometimes yellow, brown, pink or blue in the case of fancy color diamonds) which is uniform throughout the entire diamond and is constant, regardless of whether it is being tilted or not.
Here is a special definition from Cramster.com which distinguishes what differences are between dispersion and fire:
Dispersion in gemology
In the technical terminology of gemology, dispersion is the difference in the refractive index of a material at the B and G Fraunhofer wavelengths of 686.7 nm and 430.8 nm and is meant to express the degree to which a prism cut from the gemstone shows "fire", or color. Dispersion is a material property. Fire depends on the dispersion, the cut angles, the lighting environment, the refractive index, and the viewer.
My point is that while you can discuss and measure Fire if you wish to do it, that it is not going to be a valuable measure, especially for GRADING, due to the obvious variables which drastically affect the amount which can be seen or measured, namely lighting and cut angles. Also, the body color of the diamond must be discounted from the total measure if there is a tint present.
Fire is not the equal of dispersion, but without dispersion there will be no fire. When a stone has the ability to create dispersion, then how the stone is cut and how it is lit will make the fire increase or decrease. Is this a measurement that is crucial to grading diamonds? Is this a measurement which will make people decide to select one diamond over another? I don't think it is a dependable measure for grading. Admittedly, consumers might choose to pick a higher or lower than average firey diamond, but it would be a preference on their part and not anything to do with "quality" of the diamond. When you have more colored light coming to the eye, you will have less white light. It is a trade-off situation. You can't make more total light come back to the eye than the amount which went into the diamond. You can make less come back, but never will you create more energy coming out than what was sent in. Maximizing light return is a reasonable goal and should be part of cut grading.
Dispersion
Arranged around the table facet on the crown are several smaller facets (bezel and star facets) angled downward at varying degrees. These facets, and the angles at which they are cut, have been skillfully designed to break up white light as it hits the surface, separating it into its component spectral colors (for example, red, blue and green). This effect, which appears as a play of small flashes of color across the surface of the diamond as it is tilted, is what we refer to as the diamond's dispersion (also called "fire"). This play of color should not be confused with a diamond's natural body color (normally white, though sometimes yellow, brown, pink or blue in the case of fancy color diamonds) which is uniform throughout the entire diamond and is constant, regardless of whether it is being tilted or not.
Here is a special definition from Cramster.com which distinguishes what differences are between dispersion and fire:
Dispersion in gemology
In the technical terminology of gemology, dispersion is the difference in the refractive index of a material at the B and G Fraunhofer wavelengths of 686.7 nm and 430.8 nm and is meant to express the degree to which a prism cut from the gemstone shows "fire", or color. Dispersion is a material property. Fire depends on the dispersion, the cut angles, the lighting environment, the refractive index, and the viewer.
My point is that while you can discuss and measure Fire if you wish to do it, that it is not going to be a valuable measure, especially for GRADING, due to the obvious variables which drastically affect the amount which can be seen or measured, namely lighting and cut angles. Also, the body color of the diamond must be discounted from the total measure if there is a tint present.
Fire is not the equal of dispersion, but without dispersion there will be no fire. When a stone has the ability to create dispersion, then how the stone is cut and how it is lit will make the fire increase or decrease. Is this a measurement that is crucial to grading diamonds? Is this a measurement which will make people decide to select one diamond over another? I don't think it is a dependable measure for grading. Admittedly, consumers might choose to pick a higher or lower than average firey diamond, but it would be a preference on their part and not anything to do with "quality" of the diamond. When you have more colored light coming to the eye, you will have less white light. It is a trade-off situation. You can't make more total light come back to the eye than the amount which went into the diamond. You can make less come back, but never will you create more energy coming out than what was sent in. Maximizing light return is a reasonable goal and should be part of cut grading.
ChunkyCushionLover
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What about white fire?
re: Maximizing light return is a reasonable goal and should be part of cut grading
Dave ,
Do you agree what:
1)maximizing Fire Light return is same reasonable goal as maximizing total light return
2) We can improve cuts to maximize Fire light return
?
P/s You can not do cut correct cut grading based on Light return because Brilliance is not Light return( it is very easy to proof)
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Do you agree what:
1)maximizing Fire Light return is same reasonable goal as maximizing total light return
2) We can improve cuts to maximize Fire light return
I suppose it is a reasonable goal to attempt to maximize fire and/or total light return. The acceptance of the appearance of a high fire diamond is still unknown. It could be good, but may not be.
You can certainly experiment with cutting to make more fire visible. Will it "improve" or detract from the preception of cut quality? Let the consumer be the judge of that.
1)maximizing Fire Light return is same reasonable goal as maximizing total light return
2) We can improve cuts to maximize Fire light return
I suppose it is a reasonable goal to attempt to maximize fire and/or total light return. The acceptance of the appearance of a high fire diamond is still unknown. It could be good, but may not be.
You can certainly experiment with cutting to make more fire visible. Will it "improve" or detract from the preception of cut quality? Let the consumer be the judge of that.
Date: 4/30/2010 12:57:12 PM
Author: oldminer
Do you agree what:
1)maximizing Fire Light return is same reasonable goal as maximizing total light return
2) We can improve cuts to maximize Fire light return
I suppose it is a reasonable goal to attempt to maximize fire and/or total light return. The acceptance of the appearance of a high fire diamond is still unknown. It could be good, but may not be.
You can certainly experiment with cutting to make more fire visible. Will it ''improve'' or detract from the preception of cut quality? Let the consumer be the judge of that.
re:The acceptance of the appearance of a high fire diamond is still unknown. It could be good, but may not be.
I am agree, but exactly same is valid for Light return
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Serg;
It is already readilyapparent that consumers and cutters like the looks of rather high light return diamond cuts. However, when you think about "MAXIMUMIZATION" of light return I suspect you will not get a diamond which many people would prefer. Contrast and sparkle are essential ingredients, so while Light Return should be engineered high, it won''t be better beyond some point and will make the diamond look bright, but uninteresting at some level of ultimate maximization. A diamond which returns light at the expense of sparkle and contrasting patterns would not be considered a best cut by anyone''s standards. So we already accept that Light Return, what I define as Brilliancy, is best at some moderation level below maximum possible levels. I suspect the same would probably apply to a diamond constructed to display more fire. At some point it would be cut like a prism and not be what anyone would call most attractive or most salable.
Here is a link to a diamond designer who has made a very firey diamond. I have examined them in person and they do "pop". The still have large white light return going on.
http://www.bezambar.com/showthing/6576/247 Sadly, I have never seen one that had been sold to a consumer.
It is already readilyapparent that consumers and cutters like the looks of rather high light return diamond cuts. However, when you think about "MAXIMUMIZATION" of light return I suspect you will not get a diamond which many people would prefer. Contrast and sparkle are essential ingredients, so while Light Return should be engineered high, it won''t be better beyond some point and will make the diamond look bright, but uninteresting at some level of ultimate maximization. A diamond which returns light at the expense of sparkle and contrasting patterns would not be considered a best cut by anyone''s standards. So we already accept that Light Return, what I define as Brilliancy, is best at some moderation level below maximum possible levels. I suspect the same would probably apply to a diamond constructed to display more fire. At some point it would be cut like a prism and not be what anyone would call most attractive or most salable.
Here is a link to a diamond designer who has made a very firey diamond. I have examined them in person and they do "pop". The still have large white light return going on.
http://www.bezambar.com/showthing/6576/247 Sadly, I have never seen one that had been sold to a consumer.
Dave,
re: So we already accept that Light Return, what I define as Brilliancy, is best at some moderation level below maximum possible levels.
How did you receive such conclusion ? Who are "WE"? I do not accept it.
re:At some point it would be cut like a prism
It is correct only for persons who do not see difference between Dispersion and Fire. ( I do not consider world "Dispersion" as only material properties . In diamond industry I use second meaning of word Dispersion as colorful flash)
re: Sadly, I have never seen one that had been sold to a consumer.
Such cuts could not be good for big polished diamonds
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Guys,
the thread I started was about the inaccuracy of definitions, and as a result, the incorrect use of definitions.
The last 10 posts clearly demonstrate that everybody using their own definition only leads to chaos. In that way, you can all keep arguing without ever reaching even a sense of agreement.
As long as there is no agreement on definitions, there can be no attempt at measuring or grading whatsoever.
As an example, we have people saying here that Fire is not Dispersion, and others claiming that it is one and the same. So, what is correct?
Live long,
the thread I started was about the inaccuracy of definitions, and as a result, the incorrect use of definitions.
The last 10 posts clearly demonstrate that everybody using their own definition only leads to chaos. In that way, you can all keep arguing without ever reaching even a sense of agreement.
As long as there is no agreement on definitions, there can be no attempt at measuring or grading whatsoever.
As an example, we have people saying here that Fire is not Dispersion, and others claiming that it is one and the same. So, what is correct?
Live long,
re:The last 10 posts clearly demonstrate that everybody using their own definition only leads to chaos. In that way, you can all keep arguing without ever reaching even a sense of agreement.
it is wrong statement about our very interesting and helpful discussion for developing Fire definition
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Going back to definitions, let us consider my suggestion for scintillation in the first post:
"Scintillation is the combination of sparkles, white or colored, observed by an observer, when either the diamond, the light-source or the observer are moving."
Since the observed sparkles can be white or colored, this implies that scintillation is the sum of dynamic brilliance (if this is defined as observed white light) and dynamic fire. Whether the observer observes a sparkle as white or colored depends upon the observer and the light-environment. Let me explain the latter more in detail.
Take a specific light-environment and a specific diamond, moving in the same way, and only change the observer (same location of the eyes), one observer will observe certain sparkles as white, while the other will observe them as fire.
Now take one observer, one diamond, moving in the same way, and change the light-environment in a way that it still feeds the same sparkles, but with a different size of the light source. In one situation, the sparkles will be observed as white sparkles, in the other situation as fire.
Live long,
"Scintillation is the combination of sparkles, white or colored, observed by an observer, when either the diamond, the light-source or the observer are moving."
Since the observed sparkles can be white or colored, this implies that scintillation is the sum of dynamic brilliance (if this is defined as observed white light) and dynamic fire. Whether the observer observes a sparkle as white or colored depends upon the observer and the light-environment. Let me explain the latter more in detail.
Take a specific light-environment and a specific diamond, moving in the same way, and only change the observer (same location of the eyes), one observer will observe certain sparkles as white, while the other will observe them as fire.
Now take one observer, one diamond, moving in the same way, and change the light-environment in a way that it still feeds the same sparkles, but with a different size of the light source. In one situation, the sparkles will be observed as white sparkles, in the other situation as fire.
Live long,
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Fire is the colored light returned and observed by an observer.
That was my attempt at a definition in the first post. On the attempted definition of scintillation, I seemed to get agreement, I am not sure if this definition of Fire received the same agreement.
Live long,
That was my attempt at a definition in the first post. On the attempted definition of scintillation, I seemed to get agreement, I am not sure if this definition of Fire received the same agreement.
Live long,
Fire as Brilliance and of course as Scintillation can not be correctly define for static view.
Better to avoid LR terminology in definitions :Fire, Brilliance, Scintillation
If somebody use LR in definitions (in Fire definition for example), he needs firstly to give LR definition
Better to avoid LR terminology in definitions :Fire, Brilliance, Scintillation
If somebody use LR in definitions (in Fire definition for example), he needs firstly to give LR definition
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I think that you misunderstood what I said. No LR-terminology, nor reference to static or dynamic view. Maybe, it is clearer with a comma between the words light and returned.
Fire is the colored light, returned and observed by an observer.
Live long,
Fire is the colored light, returned and observed by an observer.
Live long,
ok.all 3 definitions should be writing in same style .
if "Fire is the colored light, returned and observed by an observer.." then Scintillation( or Brilliance ) is the light, returned and observed by an observer.
how is helpful such type definitions ?
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Need to correct myself. English is not my native language either.
Fire is the colored light, returned by a diamond and observed by an observer.
If you want it in comparable wording, then:
Brilliance is the white light, returned by a diamond and observed by an observer.
I do not agree with this, because there is coloured light, returned by a diamond, which is observed as white light by an observer. This gets lost in this definition.
Live long,
Fire is the colored light, returned by a diamond and observed by an observer.
If you want it in comparable wording, then:
Brilliance is the white light, returned by a diamond and observed by an observer.
I do not agree with this, because there is coloured light, returned by a diamond, which is observed as white light by an observer. This gets lost in this definition.
Live long,
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"Brilliance is the white light, returned by a diamond and observed by an observer."
"I do not agree with this, because there is coloured light, returned by a diamond, which is observed as white light by an observer. "
I would word it this way:
Brilliance is all the light returned to the observer, colored and white.
The colored light returned to the oberserver is composed of body color tinted light and visible spectral dispersion which we define as "fire".
We can measure such Brilliance rather easily in a static view images and capture repeated images to measure a meaningful statistical average using several images while the diamond is rotating but kept with its table perpendicluar to the lighting source. In this way one can use gray scale of the pixels to determine the light return. For measuring fire, one needs to use colored images and the process would be far more complex. Besides the issue of body tint, the fire seen in a standardized, normal environment, may not duplicate many observer''s experiences in other forms and types of lighting. Total light return measures (and their evntual grades) will have greater consistency and more impact on choice of which diamond to select than a fire measurement or a fire grade.
"I do not agree with this, because there is coloured light, returned by a diamond, which is observed as white light by an observer. "
I would word it this way:
Brilliance is all the light returned to the observer, colored and white.
The colored light returned to the oberserver is composed of body color tinted light and visible spectral dispersion which we define as "fire".
We can measure such Brilliance rather easily in a static view images and capture repeated images to measure a meaningful statistical average using several images while the diamond is rotating but kept with its table perpendicluar to the lighting source. In this way one can use gray scale of the pixels to determine the light return. For measuring fire, one needs to use colored images and the process would be far more complex. Besides the issue of body tint, the fire seen in a standardized, normal environment, may not duplicate many observer''s experiences in other forms and types of lighting. Total light return measures (and their evntual grades) will have greater consistency and more impact on choice of which diamond to select than a fire measurement or a fire grade.
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You are set on a definition where brilliance comprises all light, because that would make it potentially measurable. In a sense, you are reducing brilliance (which I did not define as static) to a static state, while adding fire to it (for the sake of measurement) and disregarding the observer.
The result is that you can measure ''something'' rather easily, but that you cannot correctly define what you are measuring.
The result is that you can measure ''something'' rather easily, but that you cannot correctly define what you are measuring.
ChunkyCushionLover
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I hope this suggestion does not offend anyone, but the easiest way to break new ground is to build on top of currently published literature. One of my favourite works relevant to this discussion would be this article http://www.agslab.com/spie/spie_lo_res.pdf and its definitions and explanation therein.
I think it would be significantly easier to add, clarify, or modify the peer reviewed definitions found in this article than try to reinvent the wheel.
Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be
directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,
the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes. Brilliance [can be defined] as the percentage by area of such tiny
prisms that can direct light to the observer’s eyes. This definition is simple and does not intend to account for obliquity factors that could be included to account for differences
in the relative position of facets or illumination conditions.
Gem Contrast - The high angular range ... indicates the zones in a stone crown that are not
illuminated due to the obscuration of the observer’s head. This obscuration produces what is known in the trade as
gem contrast. In proper amount and distribution, contrast creates structured lighting that enhances brilliance,
fire, and scintillation. Contrast can be a detrimental effect if t is significantly localized. Too little contrast results in a
stone appearance lacking variety under broad diffused illumination. Too much contrast results in a stone that lacks
brilliance. The combination of positive contrast characteristics and brilliance properties in a gemstone is known as contrast brilliance.
When a gemstone is in movement the contrast pattern changes in form. This effect is called dynamic contrast and adds substantial appeal to the appearance of a stone.
Gem Fire - The phenomenon of fire is one of the most appealing effects in transparent gemstones. Under favorable conditions
fire makes individual facets appear fully colored with the rainbow hues. Fire inherently occurs due to the light dispersion upon refraction as light enters and exits a stone.
Three factors determine the amount of fire perceived from a facet, namely, the angular dispersion of light upon refraction from the gemstone, the angular subtend of the source,
and the angular subtend of the eye’s pupil in relation to the facet. To best observe fire it is required to have a localized source of light so that its angular subtend is much smaller
than the angular dispersion produced by the gem facet, essentially a point source. As different colored rays arrive to the eye from a facet, some of them enter the eye’s pupil and others are blocked producing a colored appearance of the facet In this process the boundary of the eye’s pupil plays a critical role in obstructing portions of the spectrum to achieve the colored facet appearance.
Gem Scintillation - In the presence of brilliance and fire the most appealing effect is gem scintillation. Thus there are two major scintillation effects, fire and flash scintillation. To observe them it is required that the stone, the observer, or the illumination conditions be in movement. Typically the observer tilts the stone back and forth to observe scintillation and naturally optimizes for the direction that maximizes scintillation. Without brilliance ... there cannot be fire since no light can be brought to the observer’s eyes. Without fire there cannot be fire scintillation as defined by the change of fire pattern. Flash scintillation can occur without fire scintillation and it is due to ight sources not small enough in angular subtend to produce fire, or to the inability of a stone to sufficiently disperse ight for a given position of the observer. White diffused illumination will wash out both scintillation effects. Sources that subtend a small angle will contribute more to produce a flash effect, the rapid turn on and off of the light
from a given facet, than sources that subtend larger angles. Thus fire scintillation is more vivid than flash scintillation. The amount of gem scintillation perceived is linked to the brilliance and fire of a stone. However, scintillation strongly depends on the change of illumination conditions. This change is primarily produced on purpose by the movement of the stone as it is admired.
I think it would be significantly easier to add, clarify, or modify the peer reviewed definitions found in this article than try to reinvent the wheel.
Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be
directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,
the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes. Brilliance [can be defined] as the percentage by area of such tiny
prisms that can direct light to the observer’s eyes. This definition is simple and does not intend to account for obliquity factors that could be included to account for differences
in the relative position of facets or illumination conditions.
Gem Contrast - The high angular range ... indicates the zones in a stone crown that are not
illuminated due to the obscuration of the observer’s head. This obscuration produces what is known in the trade as
gem contrast. In proper amount and distribution, contrast creates structured lighting that enhances brilliance,
fire, and scintillation. Contrast can be a detrimental effect if t is significantly localized. Too little contrast results in a
stone appearance lacking variety under broad diffused illumination. Too much contrast results in a stone that lacks
brilliance. The combination of positive contrast characteristics and brilliance properties in a gemstone is known as contrast brilliance.
When a gemstone is in movement the contrast pattern changes in form. This effect is called dynamic contrast and adds substantial appeal to the appearance of a stone.
Gem Fire - The phenomenon of fire is one of the most appealing effects in transparent gemstones. Under favorable conditions
fire makes individual facets appear fully colored with the rainbow hues. Fire inherently occurs due to the light dispersion upon refraction as light enters and exits a stone.
Three factors determine the amount of fire perceived from a facet, namely, the angular dispersion of light upon refraction from the gemstone, the angular subtend of the source,
and the angular subtend of the eye’s pupil in relation to the facet. To best observe fire it is required to have a localized source of light so that its angular subtend is much smaller
than the angular dispersion produced by the gem facet, essentially a point source. As different colored rays arrive to the eye from a facet, some of them enter the eye’s pupil and others are blocked producing a colored appearance of the facet In this process the boundary of the eye’s pupil plays a critical role in obstructing portions of the spectrum to achieve the colored facet appearance.
Gem Scintillation - In the presence of brilliance and fire the most appealing effect is gem scintillation. Thus there are two major scintillation effects, fire and flash scintillation. To observe them it is required that the stone, the observer, or the illumination conditions be in movement. Typically the observer tilts the stone back and forth to observe scintillation and naturally optimizes for the direction that maximizes scintillation. Without brilliance ... there cannot be fire since no light can be brought to the observer’s eyes. Without fire there cannot be fire scintillation as defined by the change of fire pattern. Flash scintillation can occur without fire scintillation and it is due to ight sources not small enough in angular subtend to produce fire, or to the inability of a stone to sufficiently disperse ight for a given position of the observer. White diffused illumination will wash out both scintillation effects. Sources that subtend a small angle will contribute more to produce a flash effect, the rapid turn on and off of the light
from a given facet, than sources that subtend larger angles. Thus fire scintillation is more vivid than flash scintillation. The amount of gem scintillation perceived is linked to the brilliance and fire of a stone. However, scintillation strongly depends on the change of illumination conditions. This change is primarily produced on purpose by the movement of the stone as it is admired.
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We are not "disregarding the observer" as an imitation of the head obstruction of the observer is built into the model we use.
The best way to analyze an image is from a static image, not a moving video image. The net result of using multiple images is that it mimics real life views of how a diamond looks when someone sees it on a hand. It need not move to send light back to the eyes. The average of the static images gives a consistent result. You would not want inconsistent or non-repeatable results in a measurement. You grade color with a diamond held still and sometime move it and re-grade it for color when it is still. You don''t attempt to grade it when it moves. The same for clarity and assessment of eye-cleanness. You look statically several times and make an overal judgement. It is not done when it is moved. You also wait until the stone has settled in the scale and when there is no movment the scale reads correctly. Again, not in motion.
This is how "meaurements" of solid objects are accomplished. Diamonds are not liquid and we are not talking about gallons per hour of light return.
You simply do not need motion video to assess light return in a standardized environment.
If you can really measure fire in a way that is consistent, accurate and repeatable, then by all means you can do it. I am not the one in charge of these things. I am saying I do not believe you can do it with sufficent repeatability and consistency to make it mean much more than marketing material for advertising. It is not needed for "grading'', but if you can measure it properly, no problem. I don''t think it can be done in an unbiased manner with accuracy.
I have clearly defined light return in a standardized environment as the amount of light which comes back to the observer with a known amount of light being transmitted into the crown of the diamond. To me, since all white light is comprised of all the colored component wavelengths of light, the amount of total light returned is the best measure of how a specific diamond sends light back to us. Of course, there is more to beauty than just light return. Sparkle and intensity, as previously defined, cover the rest of the important data which we can measure.
Measurements compared to a sufficent number of human observations will end up creating a grading system which is correct, human and natural. It will not limit choices of cutting, but encourage more and more innovation in cut designing. It is human nature to "grade" and "categorize" things. We do it now and will always do it.
Why would you want to not measure something ''easily" instead of doing it a more difficult way that results in less accuracy repeatability and consistency? I think you would have great difficulty in defining why you would prefer to go that more complex route. You would also find it far more difficult to define what your approach means and how the many added variables interact in your measurement. It might then not be possible to use such complex measures to produce any meaningful grading scenario which I think is an important part of the mix.
The best way to analyze an image is from a static image, not a moving video image. The net result of using multiple images is that it mimics real life views of how a diamond looks when someone sees it on a hand. It need not move to send light back to the eyes. The average of the static images gives a consistent result. You would not want inconsistent or non-repeatable results in a measurement. You grade color with a diamond held still and sometime move it and re-grade it for color when it is still. You don''t attempt to grade it when it moves. The same for clarity and assessment of eye-cleanness. You look statically several times and make an overal judgement. It is not done when it is moved. You also wait until the stone has settled in the scale and when there is no movment the scale reads correctly. Again, not in motion.
This is how "meaurements" of solid objects are accomplished. Diamonds are not liquid and we are not talking about gallons per hour of light return.
You simply do not need motion video to assess light return in a standardized environment.
If you can really measure fire in a way that is consistent, accurate and repeatable, then by all means you can do it. I am not the one in charge of these things. I am saying I do not believe you can do it with sufficent repeatability and consistency to make it mean much more than marketing material for advertising. It is not needed for "grading'', but if you can measure it properly, no problem. I don''t think it can be done in an unbiased manner with accuracy.
I have clearly defined light return in a standardized environment as the amount of light which comes back to the observer with a known amount of light being transmitted into the crown of the diamond. To me, since all white light is comprised of all the colored component wavelengths of light, the amount of total light returned is the best measure of how a specific diamond sends light back to us. Of course, there is more to beauty than just light return. Sparkle and intensity, as previously defined, cover the rest of the important data which we can measure.
Measurements compared to a sufficent number of human observations will end up creating a grading system which is correct, human and natural. It will not limit choices of cutting, but encourage more and more innovation in cut designing. It is human nature to "grade" and "categorize" things. We do it now and will always do it.
Why would you want to not measure something ''easily" instead of doing it a more difficult way that results in less accuracy repeatability and consistency? I think you would have great difficulty in defining why you would prefer to go that more complex route. You would also find it far more difficult to define what your approach means and how the many added variables interact in your measurement. It might then not be possible to use such complex measures to produce any meaningful grading scenario which I think is an important part of the mix.
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David,
You are trying to define something that is observed by an observer, then limiting it to something that is measurable. So, what is it, is brilliance ''something'' observed by an observer, or ''something'' measured by a device?
If the device is not around, can it still exist or not?
Live long,
You are trying to define something that is observed by an observer, then limiting it to something that is measurable. So, what is it, is brilliance ''something'' observed by an observer, or ''something'' measured by a device?
If the device is not around, can it still exist or not?
Live long,
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You are trying to define something that is observed by an observer, then limiting it to something that is measurable. So, what is it, is brilliance ''something'' observed by an observer, or ''something'' measured by a device?
A device is engineered to become equal to a human observer''s eye, but a device is far more repeatable and discreet. It never tires or takes a day off. The amount of light return can be measured from the camera device and we can''t do that with out own eyes. The light is there, either way. The eye never measures brilliancy as it does not measure. Only a device can make a measure of light return. Combine these measures with a sufficient number of human observations and one can have a reliable grading scale. That is how it is done.
what is difference between comic book and cartoon ?
you can use static images to analyze comics, but you can not do it for cartoon.
When cartoon movies were created years ago every frame was a still image. Because of our own limitations of vision, when rapidly passed in front of the camera, the still images appeared to move and trick our mind into seeing a movie and not a series of still images. If one would slow down the projector, the still images would have become apparent as they were always present. I think it wrong to require the cut of a diamond to be assessed while the diamond is in motion when it can be much more easily assessed when it is stationary and then moved and then assessed in a new stationary position. You will nevre quantify measurements made on moving objects. Does a Helium or a Sarin take still images? How in the world could it take motion images and make those measures? We need reasonable goals to make logical measurements.
A device is engineered to become equal to a human observer''s eye, but a device is far more repeatable and discreet. It never tires or takes a day off. The amount of light return can be measured from the camera device and we can''t do that with out own eyes. The light is there, either way. The eye never measures brilliancy as it does not measure. Only a device can make a measure of light return. Combine these measures with a sufficient number of human observations and one can have a reliable grading scale. That is how it is done.
what is difference between comic book and cartoon ?
you can use static images to analyze comics, but you can not do it for cartoon.
When cartoon movies were created years ago every frame was a still image. Because of our own limitations of vision, when rapidly passed in front of the camera, the still images appeared to move and trick our mind into seeing a movie and not a series of still images. If one would slow down the projector, the still images would have become apparent as they were always present. I think it wrong to require the cut of a diamond to be assessed while the diamond is in motion when it can be much more easily assessed when it is stationary and then moved and then assessed in a new stationary position. You will nevre quantify measurements made on moving objects. Does a Helium or a Sarin take still images? How in the world could it take motion images and make those measures? We need reasonable goals to make logical measurements.
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Guys while this is intruiging, it is rather complex because of contrast / dark zones and also the distribution of where the flashes of light are coming from on the diamonds upper surfaces.
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Thank you for looking up these definitions, CCL.
Reading and re-reading them, I think that AGS did a fine job here. May I suggest that they replace the definitions currently used in the PS-tutorial?
Live long,
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