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 Post subject: Lines in sapphire
PostPosted: Thu Oct 16, 2014 11:01 am 
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Dear Members,

I got this ring and wonder what these lines in the center stone could be. They are parallel and not curved. RI and birefringence fit with sapphire and the stone has no reaction under UV light.

First I thought of growth lines but could it also be rutile needles? I am not able to see this clearly under my bino as the lines appear only if the light penetrates the stone under a certain angle which is quite impossible to reproduce there. My 2nd question is if with these features, the stone could be a synthetic or treated (cobalt/berylium diffusion p.ex.).

Image

Under other lighting conditions, the stone is quite dark blue with some intense blue reflections as those you can see in the lower part of the stone here even if the photo is quite bad as I tried to show the lines and not the reflections :oops: .

Image

Thanks in advance for your comments.

Best regards,
Christel

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 Post subject: Re: Lines in sapphire
PostPosted: Thu Oct 16, 2014 3:42 pm 
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Hi Christel, nice ring!
The "lines" you see in the sapphire are very common in the gems I mine.
They can be silver, or gold, and we call them "silk".
They are rutile, and they will often define the growth pattern in the sapphire.
They can make the finished gem seem "sleepy", and this is one reason for heat treating the rough.
If the cook is right, all the silk disappears, and the gem comes to life.
From your photos, I'm seeing a natural, untreated stone.
Barry.


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 Post subject: Re: Lines in sapphire
PostPosted: Fri Oct 17, 2014 5:02 am 
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Hi Barry,
Thanks for your reply =D>

I bought the ring this year during my holidays in Thailand and, as we all know, it's a place where a lot of treatments are done and are rarely disclosed correctly by the vendors so I was quite suspicious about the "nature" of this stone as I had only my loupe with me during the purchase.

Thanks again and best regards,
Christel

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 Post subject: Re: Lines in sapphire
PostPosted: Fri Oct 17, 2014 5:22 am 
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Hello , GIA says alternating color zones of blue and white are a Kashmir sapphire feature.


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 Post subject: Re: Lines in sapphire
PostPosted: Thu Oct 23, 2014 3:31 am 
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mrb wrote:
Hello , GIA says alternating color zones of blue and white are a Kashmir sapphire feature.


i'm sorry mrb but it's my understanding that feature doesn't exclusively belong to Kashmir sapphires, i saw that in many stones from other sources..... ;-)

ciao
alberto

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 Post subject: Re: Lines in sapphire
PostPosted: Thu Oct 23, 2014 12:53 pm 
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https://drive.google.com/file/d/0BxcAPo ... sp=sharing

Alberto , Not claiming to be an expert of anything , however , my understanding was the same as yours but then found this paper.

Pls scroll down to page 6


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 Post subject: Re: Lines in sapphire
PostPosted: Thu Oct 23, 2014 1:22 pm 
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thx for the info, mrb.
Ok, Mr. Rolf Schwieger will forgive me but i don't buy that. period.

ciao
alberto

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 Post subject: Re: Lines in sapphire
PostPosted: Thu Oct 23, 2014 1:41 pm 
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According to the paper, it's not just alternating color zones, it's sharp zones of intense blue with milky white in between (which give it that distinctive velvety look). That sounds a bit more reasonable to me.

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Last edited by Stephen Challener on Thu Oct 23, 2014 1:54 pm, edited 1 time in total.

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 Post subject: Re: Lines in sapphire
PostPosted: Thu Feb 12, 2015 10:35 am 
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Just had to chime. Little off topic, but the bracelet on page 268 looks pretty comfy. Buckle-like, nice smooth taper, amazing, fantastic style inspiration.

I think I'll just gaze at the picture, until I really feel like buckling down to business and understanding the topic at bay here. Pictures........Pictures.........Dang, I'm feeling mentally lazy.


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 Post subject: Re: Lines in sapphire
PostPosted: Fri Feb 20, 2015 8:53 am 
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I agree with Alberto, blue sapphires from many sources can display this.

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 Post subject: Re: Lines in sapphire
PostPosted: Fri Feb 20, 2015 12:01 pm 
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I also agree with Alberto.


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