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 Post subject: Re: Fake gem rough
PostPosted: Tue Mar 24, 2015 2:45 pm 
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This thread got me thinking about three little bags of tiny green rough I got in a larger parcel at one of the shows in Franklin, NC in 2013. It was labeled tsavorite but I figured it was green glass. I'm not so good with the refractometer but brought it out and checked them along with other properties.

Density: 3.80
RI: 1.73-1.74
Isotropic on polarimeter
No pleochroism
Pink with Hanneman's PMCF (and a Chelsea filter I had laying around :twisted: )

Seems a little heavy, but these are small pieces...

So....maybe it's not glass....


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 Post subject: Re: Fake gem rough
PostPosted: Tue Mar 24, 2015 2:55 pm 
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DrSue - You really need to look at the small green rough under the microscope to see if there are any characteristic inclusions, although pink through the Chelsea filter bodes well.

Recently a friend of mine cut a large stone from the green synthetic periclase, before he knew what it was. The cutting and polishing went easily, working like tanzanite. The surface of the polished stone degraded quite rapidly, developing hazy spots. I don't know what happens in the long-term, but the material is also soft (around Mohs 5) and the cleavage is easy, so it's not really viable as a wearable gem. It's an interesting curiosity - but an unhappy trap for the unwary.


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 Post subject: Re: Fake gem rough
PostPosted: Tue Mar 24, 2015 5:53 pm 
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Forgot to add....positive response to rare earth magnet.


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 Post subject: Re: Fake gem rough
PostPosted: Wed Mar 25, 2015 4:04 pm 
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great thread.
thanks everyone!

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 Post subject: Re: Fake gem rough
PostPosted: Wed Apr 01, 2015 3:05 pm 
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Love this thread. I'm always impressed with the ingenuity and creativity people use to cheat!


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 Post subject: Re: Fake gem rough
PostPosted: Sun Apr 12, 2015 4:53 pm 
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xenolithos, =D> =D> =D> you start a nice post and it will so helpful for gemologist/ trade people
I also want to contribute in this post if you like it.

Recently one of my friend calls me that got a chance (The term “chance” usually we use in local gems market Peshawar, when a person got an expensive gem in a low prices) and he found a special material in a very little amount and soon his name will be added in the list of millionaires. I said bring that material for testing and wanted that your name added in billionaires list instead of millionaires. After this discussion he said that he got a natural ruby with natural coating mother rock.
When he bring the material for testing, after checking I said I cannot help you to add your name even in thousandaires list.

Actually his material was synthetic ruby which was coated with silica dioxide power mixed with glue or bonding agent material.
The glue/bonding agent can be easily seen on the corner of the synthetic ruby surface. In UV light the glue glow white.


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 Post subject: Re: Fake gem rough
PostPosted: Tue Apr 21, 2015 2:17 pm 
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I found a similar fake, it was a large Ethiopian opal with sand glued onto the surface that showed crazing. I thought it was a little hinky but it was cheap so I picked it up anyways. No regrets!

As purchased:
Image

After removing some of the glue:
Image

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 Post subject: Re: Fake gem rough
PostPosted: Tue Apr 21, 2015 3:59 pm 
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Clever. I imagine it's really hard to tell the difference on sight between that and some of the more coherent mud/rhyolite you sometimes get on the surfaces or intergrown with the opal.

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 Post subject: Re: Fake gem rough
PostPosted: Tue Apr 21, 2015 5:51 pm 
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Someone told me that the miners like to jam mud into every crevice that they can in order to increase the weight. Don't know if it is true or not, but I suppose the sand would have the same effect.


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 Post subject: Re: Fake gem rough
PostPosted: Thu Mar 17, 2016 9:46 am 
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some interesting glass slags (from geoforum.fr)

opal-like with 'matrix'
Image
Image

Glass slags with inclusions (devitrification):
Image
Image


Last edited by cascaillou on Thu Mar 17, 2016 4:34 pm, edited 1 time in total.

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 Post subject: Re: Fake gem rough
PostPosted: Thu Mar 17, 2016 11:11 am 
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Impressive! Definitely the best slag I've ever seen.

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 Post subject: Re: Fake gem rough
PostPosted: Thu Mar 17, 2016 9:36 pm 
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the hexagonal inclusions of the third sample (cristobalite or tridymite?) are indeed impressive


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 Post subject: Re: Fake gem rough
PostPosted: Fri Mar 18, 2016 12:17 am 
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cascaillou wrote:
the hexagonal inclusions of the third sample (cristobalite or tridymite?) are indeed impressive

I think in technical, mineralogical terms we would refer to them as 'oyster crackers.'

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 Post subject: Re: Fake gem rough
PostPosted: Fri Mar 18, 2016 3:38 pm 
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I'll make sure to be using the right terminology next time :lol:


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