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 Post subject: 12-Ray Purple Sapphire of Interest
PostPosted: Fri Jul 31, 2009 1:28 am 
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8)

while checking out Vincent Pardieu's excellent links, found this on the GIA Labratory (Thialand) site:

TWELVE-RAYED STAR SAPPHIRE OF INTEREST
Garry DuToit
GIA Laboratory, Bangkok


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Figure 1: The well‐defined and symmetrical star in this 12‐rayed star sapphire is of special note.

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Figure 2

"Star sapphires are submitted to the laboratory on a regular basis and black or golden twelve-rayed stars from Thailand are not uncommon, but when this dark purple twelve-rayed star sapphire was submitted to the laboratory for identification recently it attracted our attention.

Within some sapphires rutile and hematite crystallize as inclusions in the form of very small needles and “arrowheads” or “platelet” inclusions. These inclusions run in three directions, parallel to the edges of the prism, within the basal plane. Hematite forms parallel to the first-order hexagonal prism while rutile is found on the second-order hexagonal prism. (Webster, R., 1994) If a stone contains a sufficient amount of rutile a six-rayed star is formed. If both hematite and rutile are present, a twelve-rayed star may be present.

A spot refractive index taken during the routine gemological examination was determined to be approximately 1.760 and the specific gravity taken by the hydrostatic method was found to be 4.0, which is consistent with sapphire. Microscopic examination using a standard GIA gemological microscope with magnification ranging from 10 to 60 times revealed a magnificent array of internal inclusions. Densely packed brownish rutile needles and silk with arrowhead inclusions and thin films or platelets were observed along with small rounded colorless crystals with small tension fractures associated. In addition, orangish irregular crystals were also observed (Figure 2)."

here's the .pdf to read the rest of this research article:
http://www.giathai.net/pdf/12rays_purpl ... pphire.pdf


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PostPosted: Fri Jul 31, 2009 11:51 am 
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Any word on if they need someone to provide a permanent home for it? ;)


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PostPosted: Fri Jul 31, 2009 1:36 pm 
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:lol: n00b!

you might could ask vincent if he might know anything about it. :wink: i wouldn't mind having it myself!


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PostPosted: Fri Jul 31, 2009 7:28 pm 
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Try Mr. Weinberg (Multicolour). I am not sure whether it may be available anymore - quite likely not...

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PostPosted: Fri Jul 31, 2009 8:46 pm 
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hi valeria,

i didn't know the stone belonged to Mr. Weinburg of multicolour, interesting.


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PostPosted: Sun Dec 20, 2009 9:16 am 
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i have a ray star sapphire from kashmir.very rare

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PostPosted: Sun Dec 20, 2009 12:42 pm 
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kashmirsapphire wrote:
i have a ray star sapphire from kashmir.very rare


post a pic then! :wink:
ciao
alberto

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PostPosted: Sun Dec 20, 2009 1:07 pm 
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Alberto wrote:
kashmirsapphire wrote:
i have a 6 ray star sapphire from kashmir.very rare


post a pic then! :wink:
ciao
alberto

I will post the pic tommorow,right now I m on my mobile.I do have pictures but I cudnt managed to capture the star in my camera.but u wud have an idea about the stone by its pictures.its a 6 ray star.

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PostPosted: Mon Dec 21, 2009 1:29 am 
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these are the pics alberto,a 6 ray star sapphire from kashmir mines.i m sorry i cudnt capture the star effect.can somebody help me explain how to do that?i use a sony H 50 camera.
this stone is broken across its top to bottom but still its a single stone.despite this crack the stone managed to remain one piece during its cutting process.star sapphires were not known to exist in kashmir sapphires untill recently.richard hughes mentioned in his book ruby and sapphire that there are no star sapphires in kashmir stuff.though he updated/corrected its existence on his web site but the book says no stars in kashmir.
he never travelled to kashmir sapphire mines.i regrett the information published on this world famous sapphire mine is mostly incorrect.
may be in future vincent writes a correct version after visiting the mines and studying samples.

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 Post subject: kashmir star sapphire close up pictures
PostPosted: Mon Dec 21, 2009 1:37 am 
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close up picture,u can see the crack.

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PostPosted: Mon Dec 21, 2009 4:22 am 
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kashmirsapphire wrote:
these are the pics alberto,a 6 ray star sapphire from kashmir mines.i m sorry i cudnt capture the star effect.can somebody help me explain how to do that?i .


you have to play a bit with a spot lamp (the best would be a fiber optic illuminator).
ciao
alberto

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