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Natural or man-made?
  
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paolo




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PostPosted: Mar 13, 2021 05:58    Post subject: Natural or man-made?  

I have bought a stone pendant in South-East Asia 35 years ago, but I have always wondered if this is a natural (just polished) stone, or a man-made compound.
I post 3 photos, two taken with a flash light and one with natural light.
Please let me know if it is necessary to post better photos.
Is it possible for some of you to identify with a reasonable certainty if this is artficial or not, and possibly what this is?



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Kevin Schofield




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PostPosted: Mar 13, 2021 09:11    Post subject: Re: Natural or man-made?  

Hi Paolo,

the good news is that this is a "natural" material. The light blue-green mineral is (95% certainty) turquoise, and it looks to have grown in a fine-grained sandstone matrix (the grey material with the light yellow-orange streaks).
Turquoise is a copper-aluminium phosphate which often occurs as in this form of nodular growth with no obvious crystal form within a host rock.

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John S. White
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PostPosted: Mar 13, 2021 09:24    Post subject: Re: Natural or man-made?  

It is nearly impossible to tell natural vs. manmade from photos, even very good ones like yours. However in my opinion I have to say that your turquoise pendant appears very natural.
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lluis




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PostPosted: Mar 13, 2021 09:32    Post subject: Re: Natural or man-made?  

As John says, it looks very natural...
Just Chinese turquoise tends to get greener in short time (opposite to Persian one)...

It depends on price.... If bought for nothing, well, probably man made anything (maybe odontolite, glued and shaped). If not exactly cheap, maybe genuine.....

From when I was in a jeweller stones dealer, I remember always Chinese turquoise as blue lined with black stripes. Never seen with the brown stripes.... (and the older ones tend to be greener...)

Just what I may say... You have the answer to questions I place... You may decide.

With best wishes

Lluís
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Bob Carnein




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PostPosted: Mar 13, 2021 12:22    Post subject: Re: Natural or man-made?  

There are different degrees of "man made" and "natural". Some turquoise is synthetic and has essentially the same composition as the natural stone. Some turquoise is "stabilized" by use of glues or plastics. There are a couple of tests you can try that might help to answer your question. First, heat a needle in a flame and touch it to various points on the stone. If it's "reconstituted", any plastic is likely to melt or produce an acrid smell. You could also dip a Q-tip in acetone and rub it on the stone. If it's dyed, some of the dye will probably come off on the cotton.
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Riccardo Modanesi




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PostPosted: Mar 13, 2021 14:15    Post subject: Re: Natural or man-made?  

Hi to everybody!
An opinion: the single pale blue/greenish pieces are natural turquoise, but I'm afraid it is a "reconstructed" one, i.e. the pieses are joined together by artificial glue or plastic, or shredded rock (preferably with manganese minerals) kneaded with glue, thus making a sort of "concrete". Another possibility is "stabilized" turquoise, i.e. the single pieces of turquoise are soaked by plastic or resin, in order to make them harder and therefore suitable for cutting.
Greetings from Italy by Riccardo.

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Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo.
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paolo




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PostPosted: Mar 14, 2021 00:58    Post subject: Re: Natural or man-made?  

Dear members,
Thank you so much for your help: this is surely more than I could hope for.
To summarize, I understand that there is a high probability that at least the single fragments of azure stone are natural turquoise. However the material as a whole could be natural or could be an artifact.
I'll take an action point to try and perform at least the first of the tests suggested by Bob, to see if I can go one step further in the identification process.

Now, I had not used the forum since 2016. It's really nice coming back now after several years and still finding a community of experts immediately available to cooperate: this is truly appreciated.
Thank you and best regards.
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