New Mineral Named After GIA’s John Koivula
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 Post subject: Natural Goldstone.
PostPosted: Tue Aug 05, 2014 8:31 am 
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Is there such a thing?


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 Post subject: Re: Natural Goldstone.
PostPosted: Tue Aug 05, 2014 9:09 pm 
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Hi Macvan.
If we look at the definition of goldstone you'll see that "natural goldstone" would be a misnomer.
Goldstone is defined as glass which incorporates included copper crystals.
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Wikipedia wrote:
The original manufacturing process for goldstone was invented in seventeenth-century Venice by the Miotti family, which was granted an exclusive license by the Doge. Urban legend says goldstone was an accidental discovery by unspecified Italian monks or the product of alchemy, but there is no pre-Miotti documentation to confirm this.

The most common form of goldstone is reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The initial batch is melted together from silica, copper oxide, and other metal oxides to chemically reduce the copper ions to elemental copper. The vat is then sealed off from the air and maintained within a narrow temperature range, keeping the glass hot enough to remain liquid while allowing metallic crystals to precipitate from solution without melting or oxidizing.

After a suitable crystallization period, the entire batch is cooled to a single solid mass, which is then broken out of the vat for selection and shaping. The final appearance of each batch is highly variable and heterogenous. The best material is near the center or "heart" of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix.


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 Post subject: Re: Natural Goldstone.
PostPosted: Tue Aug 05, 2014 11:08 pm 
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Indian sunstone (despite the lack of actual copper) is not a bad match for appearance (it looks much better imo but it's a similar color and also sheeny).

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 Post subject: Re: Natural Goldstone.
PostPosted: Tue Aug 05, 2014 11:22 pm 
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But, it is not goldstone. :D


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 Post subject: Re: Natural Goldstone.
PostPosted: Wed Aug 06, 2014 12:20 am 
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Barbra Voltaire wrote:
But, it is not goldstone. :D

Certainly not, and thank goodness for that.

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 Post subject: Re: Natural Goldstone.
PostPosted: Wed Aug 13, 2014 5:02 am 
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This one is blue, natural looking crust, no copper, silver flakes around .5 to 1mm throughout.Image


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 Post subject: Re: Natural Goldstone.
PostPosted: Wed Aug 13, 2014 10:55 pm 
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Image doesn't work.

Does it look kinda like this?:
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Image courtesy of Mineral Craft.com


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 Post subject: Re: Natural Goldstone.
PostPosted: Wed Aug 13, 2014 11:46 pm 
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The closest appearance-wise that you'll find to that is bloodshot iolite, which is basically Indian sunstone but with iolite instead of oligoclase.

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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 12:04 am 
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Click here for some images of bloodshot iolite


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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 1:16 am 
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Yes thanks Barbara. Still cannot get images posted, gone through the works, just not working. but your pics are very close.


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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 10:10 am 
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If you send me a pic I can post it for you.
bav@gemologyonline.com


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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 2:20 pm 
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natural golden sheen sapphire . a dealer in bangkok had a room full of its rough.

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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 4:54 pm 
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mrb. are you sure, that's natural and not been treated in some way ?

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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 9:57 pm 
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Dave , The dealer showed me a report of some private lab , regrettably I did not take a pic of it , he also had some papers saying the mtrl had been put on display on last Hong Kong show.

I had no interest beyond curiosity and saw the stones on my last day in Bangkok with clock ticking a little faster than normal so just took pics of the stones.

In case you have an interest I can send you his contact and you can ask him directly.

Mazhar


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 Post subject: Re: Natural Goldstone.
PostPosted: Thu Aug 14, 2014 11:49 pm 
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It's just essentially bronze/black star sapphires--flat faces will show a sheen rather than a legged star. I have some rough that would cut similar (but inferior) stones.

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