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 Post subject: The concept of "crystal"
PostPosted: Thu Dec 08, 2005 4:44 am 
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When we had our online chat with Richard Wise a while back, he brought up the concept of "crystal", something that was a new parameter to several of us who attended the chat.

I think it was Gemma who made the comparision of glass to lead crystal, which if I remember correctly, was a good way of putting it in a visual.

I know that it's probably hard to judge this from photos, but I came across this photo today and not to my surprise, in the description was "finest crystal" in the sense that Richard was talking about.

I then compared it to another sapphire on the same site of similar colour, clarity etc but that doesn't seem to have the same "crystal" attributes (I'm tempted to describe it as visual density, if that makes any sense).

I would like opinions of whether or not these two different sapphires reflect the concept of "crystal", or is the difference in what I am taking for "crystal" more to do with the cut? Both are unheated and free of inclusions, so I am assuming that it's not silk that is creating the difference in what I am seeing.

Next question, assuming that I've pinned down exactly what is meant by crystal, does heat treatment affect this, and if so, for better or worse?


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PostPosted: Thu Dec 08, 2005 10:25 am 
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Both have excellent crystal in my eyes.
I always think of it as the sea .. you can see 10 meters down and still see the ground, then something stirrs up the ground and the sand blurrs the view i.e. the crystal clear water.


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PostPosted: Thu Dec 08, 2005 10:56 am 
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Doos wrote:
Both have excellent crystal in my eyes.
I always think of it as the sea .. you can see 10 meters down and still see the ground, then something stirrs up the ground and the sand blurrs the view i.e. the crystal clear water.


Hmmm :( Then perhaps I don't quite have a grasp on the concept. What you are describing would be transparency to me... :?


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PostPosted: Thu Dec 08, 2005 11:07 am 
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Don't worry, I'm not convinced I have it right either.


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PostPosted: Thu Dec 08, 2005 11:12 am 
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Well, I just ordered Richard's book and hopefully I can convince some poor travelling soul coming from our head office to carry 1 1/2 kilos of fascinating knowledge for me to Egypt. Perhaps he goes into it in greater detail there. Or maybe he'll go into a bit of detail on it here :lol:


Last edited by Julie Gowans-Poli on Thu Dec 08, 2005 11:33 am, edited 1 time in total.

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PostPosted: Thu Dec 08, 2005 11:25 am 
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I think it's very hard to explain Crystal as it (atleast to me) is a an extra sensation. My sea analogy might not be the best. Richard goes in on in the book ofcourse.

The sea can be blue .. but still clear enough to see the bottom. If the water would be too blue, you can't see the bottom anymore. I think it's the subtle combination of transparancy and colour. So hard to describe.


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PostPosted: Thu Dec 08, 2005 11:42 am 
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I just thought of an example and Richard, please correct me.

Imagine a nice inclusion in the center of the stone .. if you can see the inclusion as a clear one (crisp and clear) without the aid of extra lightning, you have good Crystal in the stone.


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PostPosted: Thu Dec 08, 2005 12:01 pm 
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Doos wrote:
I just thought of an example and Richard, please correct me.

Imagine a nice inclusion in the center of the stone .. if you can see the inclusion as a clear one (crisp and clear) without the aid of extra lightning, you have good Crystal in the stone.


You know, something just occured to me reading this, it may be a pretty far out thought (you know me), but maybe someone knows.

I should probably explain what brings this to mind in the first place so that it makes sense where I am coming from (This could also just be a totally Canadian thought, lol).

Where I come from is a dry high altitude place and in the winter the air is "bright" in a way that's hard to describe and that has nothing to do with snow. You can see the details of the Rocky Mountains an hour's drive away as if you were standing next to them. The same holds true for the mountain fed streams and the water that flows in these, it's as if the water isn't really even there when you look at it. And ditto for the nights in the desert here.

Which kind of leads me to wonder if the quality of crystal might not be somehow associated with a minute (but perhaps measurable) difference in the ability of the stone to transmit heat? Is that at all possible from one stone to another of the same species and from the same mine?


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PostPosted: Thu Dec 08, 2005 12:09 pm 
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Doos wrote:
Both have excellent crystal in my eyes.
I always think of it as the sea .. you can see 10 meters down and still see the ground, then something stirrs up the ground and the sand blurrs the view i.e. the crystal clear water.


I would think pure crystal clear water you can see down 10 meters. Then add some microscopic air bubbles floating evenly throughout the water. By looking at the water you can't see bubbles. Even under 10X magnification you can't see the bubbles, but under higher power you can. Crystal is like this. These microscopic bubbles (inclussions) disturb the flow of light going into and being reflected in the stone. The more inclussions the less crystal clear the stone.

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PostPosted: Thu Dec 08, 2005 12:20 pm 
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So a stone with good crystal would be cleaner at 50x than a stone without. It's simply a question of clarity but under higher magnification than is used for grading purposes?


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PostPosted: Thu Dec 08, 2005 12:33 pm 
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africanuck wrote:
So a stone with good crystal would be cleaner at 50x than a stone without. It's simply a question of clarity but under higher magnification than is used for grading purposes?


That is what I understand it to be. Again that is only for the unifor microscopic inclussions. Some stones have large inclussions but few microscopic ones. In this case the crystal is good but it is still included.

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PostPosted: Thu Dec 08, 2005 12:40 pm 
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I didn't mean to suggest that Crystal is depended on inclusions. It was just an example to illustrate how clear the stone was that one could indeed see the inclusion as a clear one. So that you can look into the "heart" of the stone and see it crisp and clear.


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PostPosted: Thu Dec 08, 2005 1:02 pm 
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Would anyone who has a good grasp on this care to post a few photos illustrating the difference?

MJO, do you see a difference in crystal in the two stones that I linked to in the first post of this thread?


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PostPosted: Thu Dec 08, 2005 2:21 pm 
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When I look at "good crystal" properitied stones in Wise's photos in his book, they seem to have a magical quality that you can see into endlessly, as if they were conjured by Merlin. (Now I know I wrote that somewhere before . . . )


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PostPosted: Thu Dec 08, 2005 3:27 pm 
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africanuck wrote:
Would anyone who has a good grasp on this care to post a few photos illustrating the difference?

MJO, do you see a difference in crystal in the two stones that I linked to in the first post of this thread?


I can't tell the difference in the pictures you posted first but can tell you I have a Pink Pamir Spinel that is VVS1. It looks very nice until you put it next to a different spinel with the same color tone and clarity it looks quite dull. It doesn't have the life I expect from a spinel even though everything else is the same. It's as though I'm looking at it through a cheese cloth. That's a drastic difference but I think you see my point.

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