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 Post subject: Human Asterism? Manmade Stars!
PostPosted: Thu Dec 22, 2005 7:57 pm 
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Sometimes it is absolutely unbelievable what you get offered when you´re on a buying trip.

I had the pleasure of learning about the rare optical Phenomenon:
HUMAN ASTERISM :lol:

I saw a LOT of those manmade Stars in Sri Lanka recently.

Let´s start at the beginning: A hot and dizzy day near Ratnapura.

I visited a few gem dealers that day to buy star gems.

I already decided not to buy anything inthe first salesroom I entered:

The dealer´s office was dark and had no proper light to see the stones, all he had was a small torch to show me the effect. He did that holding the gem nearly under the table with a whispering "Look at this star..."

Something made me wonder about these horrible looking cabochons he showed me .

Some huge burned GEUDA "Star" Saphirres up to 400 Cts. which seemed to show a medium but still visible Asterism at first sight. It just couldn´t happen: The stones (The word gem would be inaproppriate) were just too bad in everything: Completely opaque whitish with some clouds of (overburned) blue. A Asterism effect just doesnt happen in such a case, at least not in that intensity. (may somebody correct me if i´m wrong)

After a dozen of those things landed on the table and a few dozen "No´s" left my mouth, the dealer switched to a new strategy: He thought by himself:
"Since this doesnt seem to be a completely clueless barefooted tourist - I better confuse him now." And so he said pathethic:

"Did you ever see a gold star?"
"Never heard of it.Do you mean an yellow star saphirre?"
"No. Gold with star."

I was shocked enough to hold my laughing spasm back and set up a pokerface.

"Let me see it." I said. I expected everything but this:

Flat Cabochon. Body colour golden to brass. Metallic. Heavy S.G.....

And there was a Six footed star on the surface...

:shock:

He wanted to sell me a 350 Ct. piece for 9.500 USD. I said:

"I need to show my buyers first."

He said: "OK: I give you sample stone, you bring GOOD BYERS."

And I said thank you for a 5 Ct. sample stone:

A PYRITE with surface polishing that induces a "Star" effect. Nicely domne, the faceter really hit the angles ...

All this is easily detectable with a loupe, but I just wanted to tell ya all the story ...

They do :lol:


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PostPosted: Fri Dec 23, 2005 1:49 am 
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Great story, Niki! Any chance of a photo of this "star"?


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PostPosted: Fri Dec 23, 2005 7:15 am 
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Yes, I will add it after the stress getß´s less and I have time to take some pics...


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PostPosted: Wed May 17, 2006 11:14 am 
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Alright, I have to admit I forgot to load up the picture! Forgive me, but you know, 115 db Rhythms sometimes shake up my brain at night :wink:

So here it is: One picture was taken with two light sources. Just look how this surfacial treatment resembles a double Star!

http://i21.ebayimg.com/03/i/07/27/46/09_1_sbl.JPG

http://i24.ebayimg.com/01/i/07/2d/56/3f_1_sbl.JPG


I also found this treatment on Garnets. I didn´t buy one of those, so there is no picture of them.

The "Star" in these cases (transparent quite dark material) is very weak, maybe this is the reason why the shifted over to Pyrite as an ideal material to work with.

The people also seem to concentrate their efforts on big dark and opaque saphirres of all colors. They look quite ugly, but there are always some tourists without any knowledge in stones ...

Maybe I find one Picture of these Saphirres in my album, so I can scan and load it up.

The Treatment is not easily detectable with a 10x loupe. Under stronger magnification, the surface shows parallel grooves comparable to a Vinyl disc. (I like this comparison Beats and Stones are my life.... 8) )


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PostPosted: Wed May 17, 2006 8:40 pm 
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Nice photos, Niki, thanks! I can see some poor tourist picking those up!


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PostPosted: Wed May 17, 2006 9:19 pm 
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Thanks for sharing that story & those pics.

I can just imagine trying to explain that one to a stary-eyed tourist recently returned from Sri Lanka & wondering what his ultra-rare gold star is really worth (after all, he bought it "at the source" surely it's worth more in the states!).

On the other hand, it's probably worth buying one up just to have it for laughs -- but is sounds like you paid exactly the right price!

Thanks again!

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gemcutter
http://www.torraca.net
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 Post subject: Pyrite as a Gemstone
PostPosted: Thu May 18, 2006 11:26 am 
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Pt: I see you know what I felt when I played the game with them in the Buying room that day! Actually I had some serious offers for the piece from gemologists as well as costumers. People seem to be attracted somehow - what reminds me on the fact that Pyrite was used as a Gemstone for a very long time.

You still find many jewellry, especially 14th to 16th Century from central Europe, where Pyrites were used to fill the Space between colored stones, mostly garnets.

Imagine how crazy the people back then would have been about the "Gold Star"!

The next time when I am down there again, I will revisit this particular room.

I will bring a 15 ct. synthetic grown emerald (Will tell him it´s an austrian one) crystal and trade it in for a bag of this stuff .....

That´s no lie at all, we do have labratories ... 8)


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PostPosted: Thu May 18, 2006 9:53 pm 
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Does anyone here have an idea when these mad-made stars started cropping up in the market?

Thanks!


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PostPosted: Fri May 19, 2006 9:45 am 
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The Sri Lankan Gem & Jewellry Authority, where all exported goods are to be examined by a team of excellent local gemologists, said that they first saw these stars about 25 Years ago. They also said that the only guy in Ratnapura who was able to polish these stars into the surface died about ten years ago.

Since the cutter seems to have taken the process of treatment with him into the grave, these stones most likely are goods left over from his work.

A small possibility is also there that someone managed to find out how to do it and started again.


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PostPosted: Fri May 19, 2006 1:59 pm 
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The first report of a man-made star (To my knowledge) was in 1985.
It resulted from a diffusion treatment whereby, an access of titanium oxide was allowed to form oriented needles on the surface lattice structure of corundum.
A cutter submitted his star stone to the GIA lab, because when he repolished it, he lost one leg of the star. :(


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