Oct 27 2016, 12:08 PM
QUOTE(keeting89 @ Oct 13 2016, 12:26 PM)
Hi, i have gotten the H&A image from audreys..is that okay? Any comment?
Thanks alot..
Hi Keeting,Thanks alot..
Here is what Todd from NiceIce.com replied me when I seek for his advice on your candidate diamond, hope it can help you
:QUOTE
That's a very thorough analysis and I agree with most of it. Let's make some minor tweaks. Feel free to use any or all of this on your site.
The little arrowheads that appear in the middle of the hearts pattern are always going to be erratic in structure, don't pay those any attention, none at all.
The images provided for hearts and arrows by this particular supplier are not really photographs, but rather computer generated renderings, probably generated using Sarine Computerized proportions analysis. But they can tell us a bit about the optical precision, which is not up to my standards for "Hearts and Arrows". Let's analyze the image:
The green arrows pointing to obstruction under the table facet at the base of the arrows is going to be most evident to most people without a lot of diamond evaluation experience. This obstruction will face-up black from the top down view of a clarity photograph. It is created by differences in the space around each of the hearts, which is indicated here using the color pink.
You'll notice that the varying degrees of obstruction affect the visible amount of (what should be) translucent space under the table facet. Thus the relative space within each of the triangular patterns that appear between the arrow shafts is different. This will play havoc with the manner in which light reflects throughout the diamond, it will not be evenly dispersed. You can see a difference in the depth of the red space that borders the eight sides of the table facet outline being affected by the volume of obstruction. Note that all diamonds will exhibit some degree of obstruction, but the idea is to minimize it.
Note that the larger amount of space around one of the hearts is creating the small amount of light leakage visible as black in the relative one o'clock region of the table facet.
The light blue circles indicate where the tips of the hearts appear to be twisting or bending. In reality, they are not twisting, nor bending. This is an optical illusion created by the light reflections coming off the pavilion main facets from the other side of the diamond, being different in length. See graphic this page - which I'm now reminded is more of a draft which needs to be finished.
The majority of these optical precision issues are being created by differences in the size, length and the indexing of the lower girdle facets, but it is also accentuated by the proportions of the diamond. The crown and pavilion angle measurements are only the beginning of the diamond selection process, the crown and depth measurements must also be taken into account, but these factors are more of a puzzle comprised of sliding pieces - which is why I've never attempted to write a tutorial on it, it would simply be too confusing and would likely create a logistical nightmare for the consumer.
But I can tell you that the pavilion depth of 43.5% happens to be the "critical tipping point" where light begins NOT to strike fully off the pavilion facets. Thus the full volume of light is not likely to be reflected back up from the pavilion facets (lower half of the diamond) the person observing the diamond. This is one of the reasons why Enchanted Diamonds is giving this 0.40 carat, F-color, VVS-1 clarity, GIA Excellent cut round diamond an overall cut score of 94.1% out of a possible 100%.
The shallower crown angle of 33 degrees is also a factor and is likely to produce more brilliance (white sparkle) as opposed to producing a virtual balance of brilliance and dispersion (colored sparkle) as would be likely to occur with a crown angle between 34.3 - 35.0 degrees. This effect is likely to be increased by the 80% lower girdle facet length, which is likely to produce sparkle which is smaller in size.
Due to the way our human eyes interpret sparkle that is smaller in size, it is not likely to be fully dispersed into colored sparkle. Note that the GIA rounds off the lower girdle facet length to the nearest half a percent, so the diamond might produce sparkle that is larger in size if the lower girdle facets are actually 78% which the GIA would round up to 80% and this can be visually estimated by an experienced diamond grader using the clarity photograph.
I'm definitely not a fan of lab grown diamonds, feel free to link to this article and borrow some graphics if you want (with credit of origin please, maintains validity of license). I realize that in your case this statement is kind of redundant since you seem to be very good about that already... Thank you for that.
Refer to the article Diamond Color Grading for additional insight on blue fluorescence and a really cool video. I've never seen a diamond with medium blue fluorescence that presented any negative visual properties, it can only help in my opinion. The realm of strong blue is also usually a safe bet. There is the potential for diamonds to appear "over blue" which people tend to interpret as being milky or cloudy, in the realm of very strong to distinct blue - this is where the 2% of gem quality diamonds come in, which exhibit visual properties negatively influenced by the extremely high volume of blue fluorescence. Always advise your clients to avoid diamonds exhibiting white or yellow fluorescence, that is always going to negatively influence the visual properties.
It's super cool to see you taking such an interest in diamonds :-)
The little arrowheads that appear in the middle of the hearts pattern are always going to be erratic in structure, don't pay those any attention, none at all.
The images provided for hearts and arrows by this particular supplier are not really photographs, but rather computer generated renderings, probably generated using Sarine Computerized proportions analysis. But they can tell us a bit about the optical precision, which is not up to my standards for "Hearts and Arrows". Let's analyze the image:
The green arrows pointing to obstruction under the table facet at the base of the arrows is going to be most evident to most people without a lot of diamond evaluation experience. This obstruction will face-up black from the top down view of a clarity photograph. It is created by differences in the space around each of the hearts, which is indicated here using the color pink.
You'll notice that the varying degrees of obstruction affect the visible amount of (what should be) translucent space under the table facet. Thus the relative space within each of the triangular patterns that appear between the arrow shafts is different. This will play havoc with the manner in which light reflects throughout the diamond, it will not be evenly dispersed. You can see a difference in the depth of the red space that borders the eight sides of the table facet outline being affected by the volume of obstruction. Note that all diamonds will exhibit some degree of obstruction, but the idea is to minimize it.
Note that the larger amount of space around one of the hearts is creating the small amount of light leakage visible as black in the relative one o'clock region of the table facet.
The light blue circles indicate where the tips of the hearts appear to be twisting or bending. In reality, they are not twisting, nor bending. This is an optical illusion created by the light reflections coming off the pavilion main facets from the other side of the diamond, being different in length. See graphic this page - which I'm now reminded is more of a draft which needs to be finished.
The majority of these optical precision issues are being created by differences in the size, length and the indexing of the lower girdle facets, but it is also accentuated by the proportions of the diamond. The crown and pavilion angle measurements are only the beginning of the diamond selection process, the crown and depth measurements must also be taken into account, but these factors are more of a puzzle comprised of sliding pieces - which is why I've never attempted to write a tutorial on it, it would simply be too confusing and would likely create a logistical nightmare for the consumer.
But I can tell you that the pavilion depth of 43.5% happens to be the "critical tipping point" where light begins NOT to strike fully off the pavilion facets. Thus the full volume of light is not likely to be reflected back up from the pavilion facets (lower half of the diamond) the person observing the diamond. This is one of the reasons why Enchanted Diamonds is giving this 0.40 carat, F-color, VVS-1 clarity, GIA Excellent cut round diamond an overall cut score of 94.1% out of a possible 100%.
The shallower crown angle of 33 degrees is also a factor and is likely to produce more brilliance (white sparkle) as opposed to producing a virtual balance of brilliance and dispersion (colored sparkle) as would be likely to occur with a crown angle between 34.3 - 35.0 degrees. This effect is likely to be increased by the 80% lower girdle facet length, which is likely to produce sparkle which is smaller in size.
Due to the way our human eyes interpret sparkle that is smaller in size, it is not likely to be fully dispersed into colored sparkle. Note that the GIA rounds off the lower girdle facet length to the nearest half a percent, so the diamond might produce sparkle that is larger in size if the lower girdle facets are actually 78% which the GIA would round up to 80% and this can be visually estimated by an experienced diamond grader using the clarity photograph.
I'm definitely not a fan of lab grown diamonds, feel free to link to this article and borrow some graphics if you want (with credit of origin please, maintains validity of license). I realize that in your case this statement is kind of redundant since you seem to be very good about that already... Thank you for that.
Refer to the article Diamond Color Grading for additional insight on blue fluorescence and a really cool video. I've never seen a diamond with medium blue fluorescence that presented any negative visual properties, it can only help in my opinion. The realm of strong blue is also usually a safe bet. There is the potential for diamonds to appear "over blue" which people tend to interpret as being milky or cloudy, in the realm of very strong to distinct blue - this is where the 2% of gem quality diamonds come in, which exhibit visual properties negatively influenced by the extremely high volume of blue fluorescence. Always advise your clients to avoid diamonds exhibiting white or yellow fluorescence, that is always going to negatively influence the visual properties.
It's super cool to see you taking such an interest in diamonds :-)
This post has been edited by kambingkoh: Oct 27 2016, 01:42 PM
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