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 Post subject: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 8:48 am 
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Black "lightning ridge" opals have started raining from the ebay thai dealers.

Such as this and this.

Well of course it isn't Australian blacks. But what is it? New treatment? Old treatment? Can natural Ethiopian material get that black that easily? Anyone who knows?

Edit: rough one (probably same thing?) here.

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 8:58 am 
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First of all. Photoshopped images. Probably "smoked" ethiopian opals but they do have to be tested to determine this.
Smoking is an old treatment that has shown to be very efficient on the ethiopian stones. I know Bear and Cara Williams wrote an article about this somewhere, I will check for it.

As long as you do not pay big bucks for the stones and if disclosing treatment if reselling I see no problem. If buying for yourself buy it with the treatment in mind and pay accordingly. The rough stone might be a dyed (sugared?) australian. In the last one the color might be no more than skin deep.

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 9:14 am 
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Hi

as mentioned Ethiopian Opal has been treated extensively to achive the dark body color, almost none dark body color like the one pictured exist natural in Ethiopian Opal.
Just a few months ago I was on an Gemological conference where this was one of the subjects of a talk.
So to sum it up yes it is easy to treat Ethiopian Opal to that color.
The last sample in the link is in my opinion a sugar boiled Andamookan Australian Opal

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 9:23 am 
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Nice treat earthling, then we agree :)

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 9:27 am 
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Europe agrees Conny

sugar boiled Opals
http://forums.opalauctions.com/viewtopic.php?f=13&t=740

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 10:13 am 
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I agree as well, the material appears to be sugar treated material from undetermined sources.


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 11:16 am 
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Ah, ofc :D Thanks! Certainly won't buy any, I was just confused :roll:

Quote:
Smoking is an old treatment that has shown to be very efficient on the ethiopian stones.


Makes sense, could be due to the same great porosity that makes them hydrophane and gain up to 10% weight in water? :)

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 11:27 am 
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It is also very effective on Australian opals. I used to do it in the kitchen as a hobby when I was a teenager. :D


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 3:10 pm 
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Well I'm still teenager for one more month so I need to hurry up and try that out!

:mrgreen:

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 01, 2012 3:23 pm 
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ways to darken opal:
-black dyes
-silver salts
-smoking
-sugar+H2SO4
-black doublets/triplets


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Sat Jun 02, 2012 10:25 pm 
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Most of the opal coming from Thailand is Ethiopia origin despite being described as "Australian".

I have a little dark grey one in front of me purchased on ebay.
Treated for sure.


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 29, 2012 3:35 pm 
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Chrysos wrote:
Black "lightning ridge" opals have started raining from the ebay thai dealers.

Such as this and this.

Well of course it isn't Australian blacks. But what is it? New treatment? Old treatment? Can natural Ethiopian material get that black that easily? Anyone who knows?

Edit: rough one (probably same thing?) here.


I would highly suspect smoked, sugar treated and or dyed Ethiopians.
Winter 2011 issue of Gems and Gemology had a spread on dyed Ethiopians.
I suspect all gem materials coming out of Thailand these days. My rule of thumb
is check and double check. If buying in Chantaburi, go with known BKK broker
and pay them the extra 5%. Stones can then be checked back in BKK before
payment is executed.

Have been able to acquire some nice and affordable No Enhancement Ethiopians out of India.

Bill


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Fri Jun 29, 2012 6:47 pm 
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JTV is now selling smoke-treated Ethiopian black opals under their trademarked name Chalama Opal. Unlike the totally fraudulent advertisments posted by Chrysos they disclose both the treatment and origin of the stones. Their images don't appear to be overly enhanced and their prices are realistic IMO.

http://www.jtv.com/on/demandware.store/Sites-jtv-Site/default/Search-Show?q=black+opal&x=0&y=0

The opal advertised fraudulently as Natural Australian Lighting Ridge Black Matrix Boulder Opal is treated matrix opal from Andamooka, Oz. As far as I can tell that's the primary source for opal that responds well to the sugar/acid treatment although some Honduran material is said to be enhanced the same way. This advertiser really thinks people are stupid. Lightning Ridge black opal, Matrix opal (the only truth in his headline) and Boulder opal are from three separate Australian locations and are completely different types of opal.

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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Sat Jun 30, 2012 9:40 pm 
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We ran a press release on this last year:

http://www.stonegrouplabs.com/SmokeTreatmentinWolloOpal.pdf

After experimentation we've discovered the best method has been smoke treatment and not the sugar treatment.

Regards,
Bear


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 Post subject: Re: Black opals invading Bangkok?
PostPosted: Sat Jul 21, 2012 8:12 pm 
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There sure is a lot on eBay now- and fetching rather high prices.
Advertised as Lightning Ridge.


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