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 Post subject: synth green sapphire
PostPosted: Tue Nov 09, 2010 5:15 am 
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Joined: Tue Mar 23, 2010 8:46 am
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Location: Dubai
hi all
just got this stone to test at the lab.
RI 1.76-1.77
no fluo
apple green color

see the blue bubbles in the photo...

have you ever seen synth sapphires this color? for me its the first time...
they probably dope yellow synth with blue colorants to get green..and these are residues...it seems flux grown to me
any suggestion?

ciao


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 Post subject: Re: synth green sapphire
PostPosted: Tue Nov 09, 2010 6:39 am 
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Hi Francesco,

interesting stone, the overall appearance resemble more a quench crackled FF (the honeycomb pattern, i mean), that would explain the bubbles, never saw them in a flux grown..... :roll:...... Let us know about your further tests!
ciao
alberto

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 Post subject: Re: synth green sapphire
PostPosted: Tue Nov 09, 2010 7:22 am 
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Dear studiogem,
Please see the my precious post about synthetic corundum in which I mentioned the Green synthetic Sapphire which I bought from Thailand.

viewtopic.php?f=24&t=12665

With Best Regards

HUK

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 Post subject: Re: synth green sapphire
PostPosted: Tue Nov 09, 2010 8:52 am 
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Yeah Hamid,

but that doesn't explain the bubbles.....if they're gas bubbles, of course :wink:
ciao
alberto

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 Post subject: Re: synth green sapphire
PostPosted: Wed Nov 10, 2010 1:17 am 
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i thought flux grown cause those " bubbles" look like blue drops...and yes some look like gas bubbles...

i can agree with Alberto...any idea why those blue residues?

the stone is gone so no more testing..

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 Post subject: Re: synth green sapphire
PostPosted: Wed Nov 10, 2010 4:11 am 
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studiogem wrote:
i thought flux grown cause those " bubbles" look like blue drops...and yes some look like gas bubbles...


that stone it's quite tricky: as said the veils pattern and the gas bubbles suggests FF quench crackled..OTOH those veils could be flux aswell...they reminds me some flux stones i saw years ago......definitely tricky....

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any idea why those blue residues?


no, never saw something like that in a stone like that..... :roll:

Quote:
the stone is gone so no more testing..


Amen! 8)

ciao
alberto

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 Post subject: Re: synth green sapphire
PostPosted: Wed Nov 10, 2010 4:25 am 
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I also agree with alberto.

I want to share the Gemology book "Gems" written by Michael O’ Donoghue some text without any change here (only for knowledge and awareness) in which he described the treatment of Flame Fusion Corundum and its testing method.

Verneuil Synthetics with Induced ‘Fingerprints’
Flux-healed quench-crackled Verneuil synthetic ruby and sapphire
with induced ‘fingerprints’, that closely resemble Burmese ruby and Sri Lankan sapphire, are being manufactured as by-products of the routine heat treatment of ruby and sapphire in Chanthaburi, Thailand. This enhanced synthetic is produced by first heating Verneuil boules and then plunging them into water. After cobbing to yield small facetable fragments, pieces of synthetic are heat treated in an unspecified colourless
flux for three days. For the first two days of the heat treatment
process a kerosene-fired kiln is used. Then an acetylene-fired kiln is used to complete the treatment on the third day.

According to Free et al. (1999) identifying inclusions in these treated
synthetics include:

1. Curved colour banding that was finely developed in the synthetic ruby, but wider and more diffuse in the synthetic blue sapphire.
2. A chequer-board pattern of fractures that have been induced in the synthetic ruby and sapphire by the quench-crackling process.
3. Surface-reaching fractures that have been partly ‘healed’ by infilling
solid colourless to dark-coloured flux. Occasional included gas ‘bubbles’ can be noted in solidified flux fracture fillings.

4. Solidified flux with a quite granular texture that can occasionally be
observed when a flux-filled quench-crackled fracture reaches the surface.

With Warmest Wishes

Hamid Usman Khattak (HUK)


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File comment: Rough green sapphire from the Anakie sapphire field, Central Queensland,
before (LHS) and after (RHS) diffusion with beryllium (T. Coldham photo)

H.JPG
H.JPG [ 12.26 KiB | Viewed 1886 times ]

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 Post subject: Re: synth green sapphire
PostPosted: Wed Nov 10, 2010 11:48 pm 
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studiogem wrote:
i thought flux grown cause those " bubbles" look like blue drops...and yes some look like gas bubbles...

i can agree with Alberto...any idea why those blue residues?

the stone is gone so no more testing..


The blue drops are likely an excess of the dopant used to create the color that is precipitating out of the corundum melt as a different phase. This phase is likely being nucleated by the gas bubbles which is why they probably look like blue gas bubbles. (the other phase may possibly be sometime similar to spinel). Given the intense color of the blue drops I suspect some component of cobalt in there. I had a piece of syn green spinel that was colored by a bit of nickel and cobalt if memory serves. . . I'll try to double check on that and get back to you.

As for the production method, I'd venture to say flame fusion also. Especially with the gas bubbles. Looks like flux healed fingerprints, which is not necessarily uncommon for treaters to induce in FF material.


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 Post subject: Re: synth green sapphire
PostPosted: Thu Nov 11, 2010 2:22 am 
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Well if it's FF material I can understand where the blue came from. Here's a picture of the end of a green sapphire boule from Djeva in Switzerland. Notice the blue "cap" on the boule. I looked at this under my low power jewelry bench microscope and it did have a very few visible blue "bubbles" in the main portion of the boule.

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