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Why does my diamond go dark in the middle?!

shihtzulover

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Hi Everyone,

I have had my princess cut diamond engagement ring for about 2 months now. It is 1.53 carats, F color, excellent polish and excellent symmetry - it sparkles like crazy in most lighting, except for florescent and indirect sunlight.

I noticed that when it is under bright lights and sparkling the most (like direct sunlight or halogen lamps), it develops a dark circle right in the middle - but the rest of it stays white.

What does this mean? Is it a bad cut? Should I upgrade to a different stone? The jewelry store that we bought from has an upgrade policy, so we could easily do that if we chose.
 

shihtzulover

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slg47|1297018708|2844907 said:

Thanks for the help. I read this thread a bit earlier, but does it mean that my diamond's cut isn't good? If that's the case, then I can upgrade - I just want to make sure that I understand correctly.
 

slg47

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shihtzulover|1297018900|2844909 said:
slg47|1297018708|2844907 said:

Thanks for the help. I read this thread a bit earlier, but does it mean that my diamond's cut isn't good? If that's the case, then I can upgrade - I just want to make sure that I understand correctly.

no, my understanding is that your diamond's cut IS good.
 

shihtzulover

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Here it is in the sunlight:


But in indirect sunlight, or in other light that causes less sparkle, it doesn't display the dark area:

2011-02-06_14-09-12_799.jpg

2011-02-06_14-13-50_646.jpg
 

Rhino

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Greetings,

slg, those thread deal with the darkness ones sees across the body of the diamondin spot lighting. If I am not mistaken the OP observes darkness in ambient/diffuse. That's an entirely different subject and is caused by a reason that actually does relate to cut quality while the spot lighting issues don't.

Depending on what cut grade the diamond has, there are angle combinations (like within the AGS system) that will not make GIA Ex because of brightness or patterned scintillation, as observed in the lighting shitzulover describes. Diamonds with pavilion angles that fall on the cusp of the shallow pavilion angle combos (about =<40.6 pavilion angle) can have darkness under the table if the persons focal length is closer to their eyes than the norm, like about 3-6". There are diamodns that get the GIA VG/G grade and even the AGS =>1 grade for this reason also but is more notable in these than in Ex/Ideals.

Shitzulover, if you pull the diamond back a little from your normal viewing distance or focal length you may observe the darkness fade to brightness. Make sure you are standing with the illumination (preferably diffuse/ambient daylight) behind you too and not in front of you to see the effects easier.

If you find it to be an issue you may want consider different angle combos which will dispell that darkness.

Kind regards,
 

Rhino

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shihtzulover|1297018563|2844904 said:
Hi Everyone,

I have had my princess cut diamond engagement ring for about 2 months now. It is 1.53 carats, F color, excellent polish and excellent symmetry - it sparkles like crazy in most lighting, except for florescent and indirect sunlight.

I noticed that when it is under bright lights and sparkling the most (like direct sunlight or halogen lamps), it develops a dark circle right in the middle - but the rest of it stays white.

What does this mean? Is it a bad cut? Should I upgrade to a different stone? The jewelry store that we bought from has an upgrade policy, so we could easily do that if we chose.

Oops. I may have misread but you have posted conficting statements.

In this post you first state "it sparkles like crazy in most lighting, except for florescent and indirect sunlight."

Sparkle is seen in spot lighting so I thought your issue was what you saw in florescent and indirect (meaning not direct) sunlight. In that lighting is where you observe brightness and contrast, not necessarily fire and sparkle. It is here I thought where your issues was but in your latter post you state it is in direct spot lighting where you see the darkenss. If that's the case then it may be what slg posted to.
 

Rhino

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shihtzulover|1297020404|2844929 said:
Here it is in the sunlight:


But in indirect sunlight, or in other light that causes less sparkle, it doesn't display the dark area:

In the pic it looks like a dark ring under the table. Is that what you're seeing or do you see darkness across the entire face of the diamond?
 

shihtzulover

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I'm so sorry for any confusion.

I tend to see the black area in the middle when I am in areas that make it sparkle a lot (direct sunlight is one example, like in my top pic demonstrating the black area in the middle)

When I am in lighting where it sparkles less, like in natural light but without indirect sunlight or in florescent lighting, it doesn't really display the dark area (like in the second pic that I posted).

Thanks so much for your help!


PS. I am only seeing the dark ring under the table - it looks like a dark circle in the middle.
 

Rhino

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That is odd. Usually in spot lighting, in well cut diamonds you'll actually see a general darkness across the face of the diamond and not localized in one particular area. The sparkles/flashes will be numerous and more intense of course but the contrast one sees in spot lighting is generally between fire/sparkle vs the dark body. If you look at any of the videos we shoot in spot lighting, which is almost always done, you can see exactly what I'm talking about.

If you are seeing a contrast akin to what is in that pic it may be due to proportion factors in the princess cut.

Did you get it locally? If so, and you can trade the people here (and myself if I don't know who the vendor is) can give you guidance vis this forum on what to look for that would prevent that.

Kind regards,
 

shihtzulover

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Thank you so much for your help - I genuinely appreciate it. :)

I did get it locally, but the vendor does have an trade-in policy, so that will not be a problem. I just want to ensure that I know what to look for, so that I don't run into a similar issue again.
 

yssie

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Rhino - what *is* that? It's like a ring of obstruction - in a princess?
 

Karl_K

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shihtzulover|1297020404|2844929 said:
Here it is in the sunlight:


But in indirect sunlight, or in other light that causes less sparkle, it doesn't display the dark area:

The diamond is at different angles so a comparison is not possible.
I am seeing hints of the same darkness in the bottom picture but because of the different orientation and angle cant say for sure.
I would guess that one set of chevrons are at or near 45 degrees.
 

Rockdiamond

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Hi shihtzulover!
First off- if you're not happy, and the store has an upgrade policy that works in your case, by all means take advantage.

Jon- you mentioned cut grade, which I'm sure was a oversight on your part, as you surely know that GIA does not issue cut grades for Princess cuts.
If we consider AGSL cut grading- they do grade princess cut diamonds for cut grade- but that grade is not exactly all that widely accepted- and such stones are very hard to find.

shihtzulover- no matter how well cut a diamond is, it will not shine consistently in every lighting scenario.
In general, the Princess cut design has certain weaknesses that cause the dark area you see- even in some well cut stones. Not all princess cuts react that way, but some do.
If that's the cut you love, hopefully there other aspects that make up for the darkness issue.
As I mentioned every diamond cut is a compromise to some degree.
 

dreamer_dachsie

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My diamond in an RB with stellar proportions, and when I hold it just right with the light coming from the sides, I get a similar effect. I think that diamonds can just look like that sometimes.
 

Rhino

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Yssie|1297026559|2845022 said:
Rhino - what *is* that? It's like a ring of obstruction - in a princess?

Dave you're correct. That was an oversight as GIA does not cut grade princess. Thank you kindly.

My educated guess would be that the lighter areas in the diamond in spot lighting are areas where leakage is occuring. I know it sounds odd but when you bring diamonds with with strong areas of leakage in spot lighting those areas appear lighter while the reflective areas appear darker and is where you will generally get the stronger fire too.

It's an adverse affect that can give that kind of contrast in spot lighting.

There are some clips I have shot of diamonds like this in way of cushion cuts that have mixed optics. Ie. Around the perimeter, where the stars, crown mains and upper halfs are the diamond has great light gathering and reflective abilities yet under the table has severe leakage. In spot lighting you'll see that darker appearance in that area and be able to observe the stronger fire down the crown angles yet at the same time be able to observe the watery crushed ice appearance directly under the table. On a personal note I don't enjoy that particular appearance as I prefer a more consistent look throughout (and no excessive leakage).

Since I don't have the diamond in question it is speculation but is my educated guess.

A DiamXray or accurate ASET taken with backlighting would really explain it. Were you able to acquire ASET or IdealScope on this princess? Polish/symmetry grading no matter how great or not, would not be the cause of it as it doesn't address optical symmetry and light performance characteristics.

Kind regards,
 

shihtzulover

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Since our diamond is already set, would an ASET tell us much? I have heard that you can buy the equipment to create an ASET image quite cheaply, so if we could do it while it was still set, we would be willing to try.

I spoke with my fiance and showed him this thread, and we were actually thinking about selling this one and going for an AGS000 - maybe from WhiteFlash. I know that we will not get nearly as much as we paid, but if we were to sell this diamond, roughly how much could we expect to get back? It is a 1.53 carat GIA-graded princess cut, F color, SI1 clarity, with excellent polish and excellent symmetry.

Thanks so much for your advice everyone!
 

yssie

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Rhino|1297032885|2845130 said:
Yssie|1297026559|2845022 said:
Rhino - what *is* that? It's like a ring of obstruction - in a princess?

Dave you're correct. That was an oversight as GIA does not cut grade princess. Thank you kindly.

My educated guess would be that the lighter areas in the diamond in spot lighting are areas where leakage is occuring. I know it sounds odd but when you bring diamonds with with strong areas of leakage in spot lighting those areas appear lighter while the reflective areas appear darker and is where you will generally get the stronger fire too.

It's an adverse affect that can give that kind of contrast in spot lighting.

There are some clips I have shot of diamonds like this in way of cushion cuts that have mixed optics. Ie. Around the perimeter, where the stars, crown mains and upper halfs are the diamond has great light gathering and reflective abilities yet under the table has severe leakage. In spot lighting you'll see that darker appearance in that area and be able to observe the stronger fire down the crown angles yet at the same time be able to observe the watery crushed ice appearance directly under the table. On a personal note I don't enjoy that particular appearance as I prefer a more consistent look throughout (and no excessive leakage).

Since I don't have the diamond in question it is speculation but is my educated guess.

A DiamXray or accurate ASET taken with backlighting would really explain it. Were you able to acquire ASET or IdealScope on this princess? Polish/symmetry grading no matter how great or not, would not be the cause of it as it doesn't address optical symmetry and light performance characteristics.

Kind regards,

That's really interesting - unexpected!
But I think if I understand right - it makes sense, an area of diamond that returns light to the viewer can be obstructed or can output light or do any number of other strange things in any given light type when held face-up, whereas an area of diamond that leaks light through the pavilion when face-up in those same lights - well, can't reflect or be obstructed or anything else, those areas just sit unchanged no matter what lighting type and what the "reflect-able" facets around them are doing - and that's what we're seeing here. Thank you for your explanation :))
I'd love to see some of those clips if they are available to the public, are you allowed to post links - or what to search for on vimeo?


shihtzu - hope you didn't mind me chiming in!
 

Lorelei

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. I know that we will not get nearly as much as we paid, but if we were to sell this diamond, roughly how much could we expect to get back? It is a 1.53 carat GIA-graded princess cut, F color, SI1 clarity, with excellent polish and excellent symmetry.

Thanks so much for your advice everyone!
[/quote]

Hi Shitzulover,

It is usual to only get around 30 - 50% of what you originally paid unfortunately...See if your original vendor can find you an AGS0 graded Princess so maybe you might get a better trade in price on the original stone, it is worth a try.
 

shihtzulover

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Messages
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Thanks for the advice! My fiance called and left a message for the manager of the jewelry store. I am doubting that they will be able to bring an AGS000 diamond in, since they only carry EGL and GIA-graded stones, but it won't hurt to ask. :)

I am still confused; is Rhino saying that my stone shows more brilliance in the middle, and that's why the middle goes dark under spotlighting? If that is the case, will I see it a lot with princess cuts? I was looking at ASETs of WhiteFlash's ACA princess cut stones, and they all appear to be more bright (with more red) in the middle.

This stone, for example, looks like it could have the same dark ring that mine has, since the ASET displays a red ring in the exact same place and shape: http://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-2559248.htm

I guess I'm still confused. By looking at that link, it looks like my current stone may be displaying the same phenomenon, thus possibly making it a great stone. Am I totally wrong?

Sorry for being so confused, and thanks again for everyone's help! :)
 

Rhino

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Yssie|1297034477|2845146 said:
Rhino|1297032885|2845130 said:
Yssie|1297026559|2845022 said:
Rhino - what *is* that? It's like a ring of obstruction - in a princess?

Dave you're correct. That was an oversight as GIA does not cut grade princess. Thank you kindly.

My educated guess would be that the lighter areas in the diamond in spot lighting are areas where leakage is occuring. I know it sounds odd but when you bring diamonds with with strong areas of leakage in spot lighting those areas appear lighter while the reflective areas appear darker and is where you will generally get the stronger fire too.

It's an adverse affect that can give that kind of contrast in spot lighting.

There are some clips I have shot of diamonds like this in way of cushion cuts that have mixed optics. Ie. Around the perimeter, where the stars, crown mains and upper halfs are the diamond has great light gathering and reflective abilities yet under the table has severe leakage. In spot lighting you'll see that darker appearance in that area and be able to observe the stronger fire down the crown angles yet at the same time be able to observe the watery crushed ice appearance directly under the table. On a personal note I don't enjoy that particular appearance as I prefer a more consistent look throughout (and no excessive leakage).

Since I don't have the diamond in question it is speculation but is my educated guess.

A DiamXray or accurate ASET taken with backlighting would really explain it. Were you able to acquire ASET or IdealScope on this princess? Polish/symmetry grading no matter how great or not, would not be the cause of it as it doesn't address optical symmetry and light performance characteristics.

Kind regards,

That's really interesting - unexpected!
But I think if I understand right - it makes sense, an area of diamond that returns light to the viewer can be obstructed or can output light or do any number of other strange things in any given light type when held face-up, whereas an area of diamond that leaks light through the pavilion when face-up in those same lights - well, can't reflect or be obstructed or anything else, those areas just sit unchanged no matter what lighting type and what the "reflect-able" facets around them are doing - and that's what we're seeing here. Thank you for your explanation :))
I'd love to see some of those clips if they are available to the public, are you allowed to post links - or what to search for on vimeo?


shihtzu - hope you didn't mind me chiming in!

You're grasping exactly what I'm saying Yssie.

I'd link you but forum rules prohibit the extent to which I can help you and I can not post a link to a video of mine, even if educational.

shitzu I have a definite opinion and commentary on the example you posted but again, forum rules prohibit me here as well from commenting on my experience with princess cuts with ASET's like the one you posted. My apologies.

Kind regards,
 

yssie

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shihtzulover|1297115621|2845891 said:
Thanks for the advice! My fiance called and left a message for the manager of the jewelry store. I am doubting that they will be able to bring an AGS000 diamond in, since they only carry EGL and GIA-graded stones, but it won't hurt to ask. :)

I am still confused; is Rhino saying that my stone shows more brilliance in the middle, and that's why the middle goes dark under spotlighting? If that is the case, will I see it a lot with princess cuts? I was looking at ASETs of WhiteFlash's ACA princess cut stones, and they all appear to be more bright (with more red) in the middle.

This stone, for example, looks like it could have the same dark ring that mine has, since the ASET displays a red ring in the exact same place and shape: http://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-2559248.htm

I guess I'm still confused. By looking at that link, it looks like my current stone may be displaying the same phenomenon, thus possibly making it a great stone. Am I totally wrong?

Sorry for being so confused, and thanks again for everyone's help! :)


I'm not Rhino (obviously :)) ) but I think what he's saying is exactly as you say above: your stone shows more light return in the middle and that's why the middle goes dark under spot lighting. Meaning that the area the red arrow points to is capable of returning light, the areas that the yellow arrow point to (around that dark ring of "light returning facets) are areas that allow light to escape through the pavilion (leakage).

So the stone has a well-defined area of facets that return light to you and a well-defined area of non-light-returning facets (when the stone is oriented face-up on your finger). The spotlighting condition (sunlight) highlights the difference between well and poorly light-returning areas, whereas the diffuse light is more of an equalizer. We do see this in well-cut RBs too - they do go dark in sunlight, there are a few threads on this (here and here

2011-02-06_14-09-12_799.jpg


Whereas a princess that returns light to you, the viewer, more evenly throughout the stone would look more like this in spotlighting:

cindygenit.jpg

ETA - shihtzu - the ASET - remember red and green both indicate facets that are capable of returning light to you, the viewer, when the diamond is in the same configuration as in the ASET photo. The difference is what angle the light that is returned to you is incident on the stone from - this is different from capable of outputting some light from somewhere to you, the viewer, vs. incapable of returning light to you, the viewer (which would be indicated by white/black depending on ASET setup)


ETA - oh, I see Rhino just posted whilst I was typing my post - well hopefully he will come back ::)

Rhino - I understand. I'll try my luck with google.
 

shihtzulover

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Thank you both so much!

Yssie - does this mean that I could find a better diamond that displays the same light return everywhere? I guess that I'm confused, because the ASETs of even the best-cut princess show more red in the middle - especially like in the ASET for the WhiteFlash diamond that I posted.

The odd thing to me is that the diamond does not seem any more or less sparkly in the middle. It seems pretty uniform to me, but then again, I'm not an expert. :)



ETA: I just read your ETA, Yssie, and that makes sense. Are you saying that since the ASET that I posted shows red and green, the whole thing would go dark in spotlighting, while my stone is likely to show red or green in the middle, with black or white around that?

Why does my whole stone seem to be sparkly all over then?


Sorry for asking so many questions. I truly do appreciate all of your help!
 

yssie

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ETA: I just read your ETA, Yssie, and that makes sense. Are you saying that since the ASET that I posted shows red and green, the whole thing would go dark in spotlighting, while my stone is likely to show red or green in the middle, with black or white around that?

yeah, I reckon.

Why does my whole stone seem to be sparkly all over then?

Two reasons - first, I think for most people what we think of as "sparkle" is by definition dependent on motion, of the stone or of something important in its environment - the sparks of light that shoot out of the stone when you turn it ever so slightly, when a leaf moves and lets a ray of sunlight through, when you're admiring your stone in your office cubicle and certain facets/groups of facets change from black to white when you lean over your ring and wiggle your finger. Even a little change in angle will allow light to hit the stone at slightly different angles, changing what facets return light/allow light escape - I think without freezing an instant in time and configuration like w/ a camera it is very difficult for even keen-eyed folk to pinpoint and follow the "actions" of a facet or a small group of facets!

Second - you have two eyes. What your brain understands from what two eyes tell it is different - more forgiving, generally - than what it would understand if you had only one eye (or a one-eyed scope like IS/ASET). There is an article on here that describes how if one eye sees a sparkle and the other sees nothing your brain understands "sparkle" - I'll see if I can dig it up.

ETA - this article: http://www.gemology.ru/cut/english/conferens-article/6.htm from this thread: [URL='https://www.pricescope.com/community/threads/do-not-request-aset-images-for-round-diamonds.153890/page-2']https://www.pricescope.com/community/threads/do-not-request-aset-images-for-round-diamonds.153890/page-2[/URL] thread is worth a read through too for all sorts of reasons 8)
 

LGK

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What yssie just said- if you haven't trained your eyes, and you don't have a comparison in front of you, it's tough to actually spot that a diamond is not returning much sparkle/fire/light out of a certain area. It just registers as "Oooh sparkly" and you don't really notice that yes, sparkly, but the outer facets are a bit lazy and not doing much but just sitting there, and the inner ones are doing all the work. Or whatever.

When I buy antique jewelry I try to have a well cut example of whatever stone I'm looking at to compare, just for this reason. it's not always until you see what a well cut diamond can do, right next to one that's mediocre, that you spot the weak areas of light return. And it's not every type of light that shows the weaknesses in some cuts.

Just a thought.
 
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