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 Post subject: Curious fire opal
PostPosted: Sun Jul 03, 2016 4:46 pm 
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This is another curiosity I found in Sainte-Marie.
I was in the shop of an opal seller, and in the middle of the classic australian ones, I see this red stone in its little box.
I ask the seller : "What is this ?"
He answers : "I don't know."
And he explains that he bought this stone online as a mexican fire opal, but when he received the stone he had his doubts, and now he doesn't know what to think about it.
It is a deep vermilion red, and under direct sunshine there is something like a blue reflection that surrounds the stone and swathes it with a pinkish-purplish halo, result of mixing red with blue.
It looks like a blue coating on a red piece of plastic.
I am interested in examining this stone more in depth with more tools, and the co-seller insists that I should be sold very cheap what he is convinced is a plastic fake with an outlandish purplish look.
Here is a picture of the stone. You must imagine that under the sun, the blueish spots are strong, moving, and surround the stone completely.
Now that I could check it, guess what ? It is a real opal. Red, with blue play-of-color. Ever seen something like that before ?


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 Post subject: Re: Curious fire opal
PostPosted: Sun Jul 03, 2016 5:01 pm 
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Cool!

Checked whether it is a contra luz?

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 Post subject: Re: Curious fire opal
PostPosted: Sun Jul 03, 2016 5:03 pm 
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No it's not. It needs reflected light to show the blue effect, not transmitted light.


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 Post subject: Re: Curious fire opal
PostPosted: Sun Jul 03, 2016 5:06 pm 
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Let us know what you figure out and if Kool-Aid had anything to do with it.


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 Post subject: Re: Curious fire opal
PostPosted: Sun Jul 03, 2016 5:09 pm 
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Cherry Kool-Aid has definitely something to do with it, from a color point of view !


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 Post subject: Re: Curious fire opal
PostPosted: Sun Jul 03, 2016 5:25 pm 
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I love Wikipedia...

Kool-Aid...

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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 2:47 am 
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Dyed Ethiopian opal most likely, with blue fire. Commonly mislabeled as Mexican, and if they do a good job it can be hard to tell. In one case reported in GnG, a questionable opal was immersed and promptly turned the water orange, suggesting to me they took the 'fanta' descriptor a bit literally.

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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 5:30 am 
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I would never have thought about this one ! Thank you Stephen.
I'll try to put it in water tonight and check what happens. I promise not to drink the water if it turns orange.
If it does not, do you know of any other means to look for a possible dyeing ? A bath of acetone maybe ?


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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 5:49 am 
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Ten or fifteen years ago fire opal was considered top quality if it showed the usual play of colors within the reddish/orange base color. This is from John, my jeweler who used to work this material & remembers being told the good stuff showed like opal with light, floating colors in the base color. I thought Mexican fire opal was a rich orange color that could reflect light depending on cut/clarity-asking?... :?: 8)


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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 12:43 pm 
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Photo Courtesy of the Gemological Institute of Cambodia
Image
DYED ETHIOPIAN OPALS
Kool-Aid IS a common dye for porous opals.
When I went to the Sinkankas Opal Symposium one of the speakers dropped an Ethiopian (OPAL) in a glass of Cabarnet. Within a few minutes, it changed from white to a rich dark red. The dye is allegedly permanent.


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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 1:54 pm 
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It can certainly present a challenge. Some of them are permanent, others less so--the orange one I mentioned lost some color after water immersion:

Gems and Gemology, Fall 2013 wrote:
Water Immersion Reveals Dye in Fire Opal
Image


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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 1:55 pm 
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Looks like a bunch of Smarties ! :shock:
I have dipped the stone into water, so far nothing happens.
As I don't drink wine and have no Cabernet at home, I'll try later to rub it with alcohol and acetone (not that I drink these either !)


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 Post subject: Re: Curious fire opal
PostPosted: Mon Jul 04, 2016 5:23 pm 
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Barbra Voltaire wrote:
Photo Courtesy of the Gemological Institute of Cambodia
Image
DYED ETHIOPIAN OPALS
Kool-Aid IS a common dye for porous opals.
When I went to the Sinkankas Opal Symposium one of the speakers dropped an Ethiopian (OPAL) in a glass of Cabarnet. Within a few minutes, it changed from white to a rich dark red. The dye is allegedly permanent.


Yummy - Jelly beans...

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 Post subject: Re: Curious fire opal
PostPosted: Tue Jul 05, 2016 5:14 am 
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So, the water in which the opal spent the night stayed colorless and clear.
The solvents, alcohol and acetone, revealed nothing.
The only thing is, it is an hydrophane opal. It became very transparent after its overnight bath, and the blue play of color has nearly vanished.
Which doesn't help me much for determination, since both ethiopian and mexican opals can be hydrophane.


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 Post subject: Re: Curious fire opal
PostPosted: Tue Jul 05, 2016 12:17 pm 
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Don't worry Isi. You didn't kill it. The color will come back within 2 weeks.
I suspect your opal is Ethiopian, not Mexican.
Why?
This crazy color process is commonly seen with Ethiopian goods. Therefore that is probable origin, IMO.


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