Can a GG or a cutter here explain this checkerboard diamond?

[kenny]

How can a cloud cause light to change colors in this geometric pattern?
I'm so intrigued!!!!
I know we have some GIA Graduate Gemologists and cutters here on Rocky Talk.

Here is the vendor's description, but I was hoping for a deeper technical explanation.
"A unique 0.40ct Radiant shape Fancy Pinkish Brown diamond. The face up of the stone contains 2 different colors , 2 of the facets appear as brown and 2 appears as pink. Unlike usual fancy color diamonds when the 2 colors blends , in this case the face up color splits into 2. This happens due to a cloud in a certain location the color split and appear as in a checker board. A real collector piece.

http://www.fancydiamonds.net/view_diamonds/6095.htm

 

[Circe]

Re: Can a GG or a cutter here explain this checkerboard diam

I've never seen anything like that before, but I'm going to guess it's the colorful equivalent of a reflector inclusion (particularly because of the way the lower left quadrant is diffusing and redirecting into the lower right) - what a weird and wonderful shot!

 

[armywife13]

Re: Can a GG or a cutter here explain this checkerboard diam

Wow, I have never seen anything like that. I am interested to find out about this, as well. It makes for an interesting diamond, thats for sure.

 

[kenny]

Re: Can a GG or a cutter here explain this checkerboard diam

Pinkish brown is not a relatively expensive color and I found out it sold 90 seconds after being posted on their site.
(Not to me )
I've been looking for a small brown to add to my FCD collection.

 

[_BUQARI_]

Re: Can a GG or a cutter here explain this checkerboard diam

This is probably a Pleochroic (Pleochroism), Dichroic or Trichroic diamond - that's why the color is "opposite" when cutted.
This does happen especially in Pink diamonds, not usual - but more often in Pink than in any other FCDs!

As you can see; the Pink checkers are pointing at eachother.
And the brown are pointing at eachother as well - but opposite.
If split and cut into 4 individual diamonds - they will probably all turn into checker diamonds.

There's not a lot of information anywhere regarding this matter.
So it might not be any easy answer WHY it does happen in some diamonds.

GIA is NOT stating this in the Reports either.
Probably even they dont know.

The diamond pictured isn't cleaved into different patterns (checkered) as it is Round Brilliant Cut.
But when seen in different angles; it change from Brown to Pink, and opposite!

http://www.gemstones-guide.com/Effect-of-Pleochroism-on-Gemstone.html

http://www.ebay.com/itm/251032259591?ssPageName=STRK:MESOX:IT&_trksid=p3984.m1562.l2649

 

[jaebond]

Re: Can a GG or a cutter here explain this checkerboard diam

Very cool. I would love to see the Figure 7 that is mentioned...

 

[oldminer]

Re: Can a GG or a cutter here explain this checkerboard diam

What you see is the efect of cutting a diamond in a particular way that lets a colored zone unequally display its color in an unusual and interesting way. To say any diamond shows Pleochroism is a real mis-use of the term. By definition, diamond, is singly refractive and therefore is Never going to show "pleochroism". Pleochroism is only defined as being seen under polarized light circumstances in doubly refractive gem materials. Diamond is isometric, always singly refractive and is not ever pleochroic. That isn't to say that the checkerboard stone isn't a reall collector's item or not unusual It is a great example of a unique diamond.

The round diamond suggested by the above poster definitely shows the two colors also, but sure is no checkerboard. It does indicate the possibility of a diamond showing two rather distinct colors, but it is based on the presence of a color zone and the cutting, not on the nature of a doubly refractive crystal which is what creates pleochroism.

You really have to wonder and shake your head why GIA would ever say the color distribution of the round diamond is "even". Nothing could be further from reality. We can all see it isn't even. Maybe they mean the depth of the colors is rather equal throughout, but the distribution is surely far from even.

I sure wonder how that checkerboard stone was lit for the photo and how it would look at various angles away from direclty face-up. Never have seen one like it.

 

[_BUQARI_]

Re: Can a GG or a cutter here explain this checkerboard diam

What you see is the efect of cutting a diamond in a particular way that lets a colored zone unequally display its color in an unusual and interesting way. To say any diamond shows Pleochroism is a real mis-use of the term. By definition, diamond, is singly refractive and therefore is Never going to show "pleochroism". Pleochroism is only defined as being seen under polarized light circumstances in doubly refractive gem materials. Diamond is isometric, always singly refractive and is not ever pleochroic. That isn't to say that the checkerboard stone isn't a reall collector's item or not unusual It is a great example of a unique diamond.

The round diamond suggested by the above poster definitely shows the two colors also, but sure is no checkerboard. It does indicate the possibility of a diamond showing two rather distinct colors, but it is based on the presence of a color zone and the cutting, not on the nature of a doubly refractive crystal which is what creates pleochroism.

You really have to wonder and shake your head why GIA would ever say the color distribution of the round diamond is "even". Nothing could be further from reality. We can all see it isn't even. Maybe they mean the depth of the colors is rather equal throughout, but the distribution is surely far from even.

I sure wonder how that checkerboard stone was lit for the photo and how it would look at various angles away from direclty face-up. Never have seen one like it.

Sorry, but I have to disagree.
I've seen rapaports providing this information, if I find it I will provide it here as well.
Pleochroism is the reason why "color change" diamonds excist, there's no known diamonds that change color but some do (not talking Chameleons).
Diamonds that got Pleochroism also show different intensity of color when held under for example Fluorescent Light vs. Incandescent Light.
I never said it were usual, I said it happens more often in Pinkish Brown - Brownish Pink diamonds than in any other FCD's.

At the "checkered" one we are talking about here - it's all because of the cut, nothing else.
As it shows one color to the left, and another to the right - it's all because how the light is affecting the color, and how the light is entering the diamond.
Then again it's Plechroism, I'm personally 100% sure, no doubt.

GIA grade it to be "even" as it shows the same mixed color throughout the whole diamond.
There's no color breaks in it - it do only show different colors when held at different angles.

 

[oldminer]

Re: Can a GG or a cutter here explain this checkerboard diam

Sorry, but regardless of how a word may be misused, it is an incorrect word for what is taking place in a diamond. Please take the time to find the proper definition and understand that using a scientific term in a way that corrupts its proper meaning is not professional. The phenonmenon exists and it can be properly described without misusing terminology. No matter who uses it wrong, even the GIA, does not make it correct nor change what this particular word means. Yes, we do see two colors, but no, it is not properly called pleochroism.

The definition of "even" you gave makes sense in the context of your explanation. It usre does not describe what an even color is, but it could be said it describes and even amount of varied color, I suppose. It is also a rather unusual effect we see here that is not often described at all.

 

[TitanCi]

Re: Can a GG or a cutter here explain this checkerboard diam

What you see is the efect of cutting a diamond in a particular way that lets a colored zone unequally display its color in an unusual and interesting way. To say any diamond shows Pleochroism is a real mis-use of the term. By definition, diamond, is singly refractive and therefore is Never going to show "pleochroism". Pleochroism is only defined as being seen under polarized light circumstances in doubly refractive gem materials. Diamond is isometric, always singly refractive and is not ever pleochroic. That isn't to say that the checkerboard stone isn't a reall collector's item or not unusual It is a great example of a unique diamond.

The round diamond suggested by the above poster definitely shows the two colors also, but sure is no checkerboard. It does indicate the possibility of a diamond showing two rather distinct colors, but it is based on the presence of a color zone and the cutting, not on the nature of a doubly refractive crystal which is what creates pleochroism.

You really have to wonder and shake your head why GIA would ever say the color distribution of the round diamond is "even". Nothing could be further from reality. We can all see it isn't even. Maybe they mean the depth of the colors is rather equal throughout, but the distribution is surely far from even.

I sure wonder how that checkerboard stone was lit for the photo and how it would look at various angles away from direclty face-up. Never have seen one like it.

Sorry, but I have to disagree.
I've seen rapaports providing this information, if I find it I will provide it here as well.
Pleochroism is the reason why "color change" diamonds excist, there's no known diamonds that change color but some do (not talking Chameleons).
Diamonds that got Pleochroism also show different intensity of color when held under for example Fluorescent Light vs. Incandescent Light.
I never said it were usual, I said it happens more often in Pinkish Brown - Brownish Pink diamonds than in any other FCD's.

At the "checkered" one we are talking about here - it's all because of the cut, nothing else.
As it shows one color to the left, and another to the right - it's all because how the light is affecting the color, and how the light is entering the diamond.
Then again it's Plechroism, I'm personally 100% sure, no doubt.

GIA grade it to be "even" as it shows the same mixed color throughout the whole diamond.
There's no color breaks in it - it do only show different colors when held at different angles.

According to the word pleochroism, change seems to be exhibited in the presence of polarized light. http://en.wikipedia.org/wiki/Pleochroism
Incandescent and fluorescent lighting, as far as I'm aware, doesn't have polarization to it, right?

Very interesting debate..

 

[Circe]

Re: Can a GG or a cutter here explain this checkerboard diam

It's not really a debate, though, not unless you use the term really loosely - OldMiner's right. Some stones, like sapphire and andalusite, do indeed display color-change qualities because of their pleochroism. Others, like garnet, spinel, and diamond, though they can change colors, do so for a variety of completely different reasons. But none of them will give a stone a checkerboard effect - even if the phrase has been used to suggest such a thing elsewhere, that just means it's been misused elsewhere. Something else going on here ....

 

[Texas Leaguer]

Re: Can a GG or a cutter here explain this checkerboard diam

Cool diamond and interesting topic! Thanks for posting Kenny.

I will preface my remarks by saying I am NOT any kind of expert on colored diamonds. I know there are others here who are, Kenny included.

I agree with Dave that diamonds simply cannot be pleochroic, as they have only one optic axis. However, they can occassionally exhibit multiple colors as displayed very interestingly in this specimen. My simple explanation would be that seperate color causing impurities can exist in different areas of the same stone, color zoning if you will. Depending on the cutting they may be observable as distinct colors when viewed from different angles or in this case two distinct colors when viewed from the same angle. This specimen is an example of a very skilled cutter, or more likely, very lucky one!

Ealier in my career I spend alot of time trapesing around the world dealing in colored gemstones, sapphires in particular. Sapphires come in a full spectrum of colors and sometimes two or more colors in the same rough. They are charmingly referred to as "party color" sapphires. To me, this is a party color diamond!

I bounced this off Alethea Inns at the AGS lab and she made the following remarks of a more scientific nature:
In the case of this diamond, it looks like it might have brownish/pinkish internal graining that might be working in conjunction with strategic cutting. It could be color zoning, but I think graining is more likely. Diamonds can be color zoned due to impurities, radiation staining/zoning, graining, etc.

 

[Karl_K]

Re: Can a GG or a cutter here explain this checkerboard diam

That is kewl
No real idea why it does it but the skill of the cutter WOW