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 Post subject: Cristinite
PostPosted: Wed Jan 25, 2012 11:27 am 
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This first section is an edited repost from August of last year I believe - I wanted to include it here with the next test cut from David Hudson. I think this belongs best under the Synthetics and Treatments Category - these stones are test cuts, and David cranks them out!

*************************************************

Just in from David Hudson.

David faceted this first prototype in a suite of twelve unique designs that I’m working on. This was cut in Cristinite. David knocked this stone out fast and did not worry about exact meet points, and he wanted me to pass that info on - quick and dirty – the prototype was to test the design.

I received the gem in the mail two days ago and the stone is fantastic in low light with beautiful pattern interaction - the stone literally glows. In sharp direct light the stone suffers a bit from extinction, but with great scintillation. I’m confident increased pavilion angles will help with this. On to the next test cut, and probably the last.

I think for quick and dirty David did an excellent job!

Image

Image

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 Post subject: Re: Cristinite
PostPosted: Wed Jan 25, 2012 11:30 am 
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Location: Where did summer go? :(
Can't wait to see what it looks like when he takes his time :shock: !

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 Post subject: Re: Cristinite
PostPosted: Wed Jan 25, 2012 11:32 am 
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Here's the second test cut from David Hudson in Cristinite. 8.40 ct


Image

Image

Still not quite happy with the design - a couple more to go.

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 Post subject: Re: Cristinite
PostPosted: Thu Jan 26, 2012 10:30 am 
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just curious, what is called christinite ? is it CZ ?


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 Post subject: Re: Cristinite
PostPosted: Thu Jan 26, 2012 11:00 am 
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cascaillou wrote:
just curious, what is called christinite ? is it CZ ?


Cristinite is an entirely different synthetic to CZ.

From what I understand, it is reconstituted chrysoprase, made under specific lab conditions with some added dopants. Technically it could be synthetic transparent Chalcedony, however if they simply melted it, kept the silica and didn't get any crystallization, it would be glass.

Depending on the colour and batch, optical properties and SG do vary wildly.

It is made in Australia, and has a bit of a following with hobbyists, but at a similar price to synthetic spinel or CZ, is not super popular for jewelry.


Last edited by Lawrence on Thu Jan 26, 2012 7:22 pm, edited 1 time in total.

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 Post subject: Re: Cristinite
PostPosted: Thu Jan 26, 2012 11:14 am 
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I found a site selling the stuff:
http://www.gemcutter.com/cristinite.htm

I would be curious to have someone test the material with crossed polars and let us know the reaction.


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 Post subject: Re: Cristinite
PostPosted: Thu Jan 26, 2012 3:44 pm 
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Considering material for test cuts Dale Hudson suggested the Cristinite that he has been working with. I think he's been practicing on this in prep for his current International Faceting Challenge. I didn't want high refractive CZ or lower refractive Quartz - it seemed a very easy and ready choice, and very inexpensive - and Dale was quite familiar with it to boot.

Testing without worrying about weight return - speeds the process up dramatically.

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 Post subject: Re: Cristinite
PostPosted: Thu Jan 26, 2012 4:26 pm 
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Barbra Voltaire wrote:
I would be curious to have someone test the material with crossed polars and let us know the reaction.

Why bother? If it weren't glass, the "inventor" or some scientist would have written a technical article touting it as the only known gem material in that RI range that was not birefringent, and they would have published an X-ray diffraction pattern to prove it. :D


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 Post subject: Re: Cristinite
PostPosted: Fri Jan 27, 2012 3:21 pm 
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I'm curious to know what is the exact chemical composition (SiO2?), what are the dopants, what is the structure (amorphous, cryptocrystalline, or crystalline? isotropic or anisotropic?) and what's the fabrication process (fusion?).
If someone finds out let us know :-)


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 Post subject: Re: Cristinite
PostPosted: Sat Jan 28, 2012 7:23 am 
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Jeffrey Hunt wrote:
Here's the second test cut from David Hudson in Cristinite. 8.40 ct


Image

Image

Still not quite happy with the design - a couple more to go.


Not happy with the design ???

I'm dreaming to be able to do that :D !


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 Post subject: Re: Cristinite
PostPosted: Sat Jan 28, 2012 10:55 am 
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Cristinite is a trade name for a variety of silica-based doped glasses of varying SG and RI, but all sold under the name "Cristinite". It's just a made-up name for marketing.
The material is cheap and easy to cut and polish if you are not too aggressive at the coarser stages, because it is rather brittle.

This makes it an ideal material for test cutting or maybe even earrings or pendants for re-sale, so long as the customer is warned "It's brittle!"

Wayne


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 Post subject: Re: Cristinite
PostPosted: Sat Jan 28, 2012 11:11 am 
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Wayne, thank you for the definitive answer.
Dr. Hanneman was correct and it is what I suspected as well.
Cristinite=GLASS.


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 Post subject: Re: Cristinite
PostPosted: Sat Jan 28, 2012 11:38 am 
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With a controlled RI this Cristinite is the perfect glass for what I was looking for with a test cut - I originally had this post under Synthetics and Treatments. :)

Thank you everyone for more info too!

There will be a few more photos of this material-and design down the line, and I believe the design will be available to anyone who wants to try their hand at it - via the Gemology Project.

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 Post subject: Re: Cristinite
PostPosted: Sat Jan 28, 2012 12:00 pm 
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Jeffrey Hunt wrote:
With a controlled RI this Cristinite is the perfect glass for what I was looking for with a test cut - I originally had this post under Synthetics and Treatments. :)
.


It was moved because the premise of the thread is not about "Cristinite: man-made glass", it is about lapidary.
:D


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 Post subject: Re: Cristinite
PostPosted: Mon Jun 11, 2012 2:24 pm 
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Another lovely Cristinite faceted by David Hudson - photographed last night. This is a prototype design by myself.


Image

-Jeff

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