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 Post subject: Unheated Ceylon 5+ carat sapphire with arrowhead inclusions?
PostPosted: Wed Apr 01, 2020 3:52 pm 
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Hi all, I also purchased a 5.78 carat sapphire ring in supposedly its original Art Deco setting that came with a NAGL (North American geological laboratory) certificate signed by a Thomas B Elliott (GJG, GIA NAJA member) stating unheated nature of sapphire, but does not go into detail what tests were done to come to that conclusion.

Given NAGL is not a big name like AGL or GIA, can anyone attest to its reputation?

Also, I included some photos under the loupe of what to me looks like they could be arrowhead silk inclusions? Do those alone confirm an unheated status? Or is it possible nowadays that sapphires are exposed to low heat treatment and can still retain such inclusions? Should I send to GIA or AGL and if so what special tests must be done to detect low level heating?

In summary,

1. Given the ring cost quite a bit (around $14000), can I be confident based on what I have now that this is indeed an unheated sapphire?

Thank you as always and I look forward to your teaching!


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Wed Apr 01, 2020 10:46 pm 
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Those do look like intact rutile inclusions which should rule out high temperature heat treatment. Unfortunately I don't think there's any reliable way to detect low temperature treatment, but it is also a much less drastic treatment.

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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Wed Apr 01, 2020 11:14 pm 
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The appraisal document looks solid to me.


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Thu Apr 02, 2020 12:07 am 
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The presence of unbroken, and fairly course rutile silk would confirm that this stone was not subjected to high temperature heat treatment.

Low temperature heat treatment is a different story, and much more difficult to recognize currently. There is some research that suggests that changes to included crystals, and the fractures around them may provide evidence of low temperature heat treatment. This is current research, and I am not aware of any labs that currently make the determination for low temperature heat as part of their report.

So, using today's standards this stone will be called not treated. As our knowledge and technology expands the potential for this to change in the future exists. But we can only work and make our decisions in the current environment.

For your reference:
https://www.lotusgemology.com/index.php ... xperiments


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Thu Apr 02, 2020 12:52 am 
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A bit late to the party, but these thick unbroken silk are fairly common in unheated sapphires from Sri lanka.
If you are based in the US, you can send it to AGL for your peace of mind.


Image
Nice rutile silk in unheated sapphire. If you want to compare :wink:


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Sun Apr 05, 2020 9:50 pm 
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Thank you to all for your thoughts and the lovely comparison photos!

Of note, I noticed a dark mark on one shoulder on both sides. Is this an old solder mark (repair with non platinum?), or gunk (does not come off with warm water/soap/brush). Should I be worried in terms of structural integrity of the setting and take it in to get looked at by a local bench (once COVID is over...).

See circled area on shoulder below (the ring is flipped to show both sides of the same affected shoulder):


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Mon Apr 06, 2020 11:45 am 
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Quote:
Should I be worried in terms of structural integrity of the setting and take it in to get looked at by a local bench (once COVID is over...).

No problem with structural integrity. Are you wearing the ring?
I think bringing it to someone who works with platinum would be a good idea for the future, Good cleaning and a repolish would improve the look of the ring.


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Tue Apr 07, 2020 11:25 pm 
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Dear Barbra,

Thanks for the advice. Yes, I wear it most days. Any good bench/jeweler you recommend in SF for a good platinum clean/polish servicing and checking the prongs?


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 Post subject: Re: Unheated Ceylon 5+ carat sapphire with arrowhead inclusi
PostPosted: Fri May 29, 2020 12:53 pm 
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Hello all,

As this was brought up by a post here, this is just to give some additional information. AGL has been disclosing relatively low temperature heating on our reports for more than 11 years now. Throughout my career, I regularly worked on this very topic and so have had robust criterion in place over this time.

I always saw relatively low temperature heating in a way as a positive. When heating at relatively low temperatures, this is really just a topic of color modification. At these temperatures (below the threshold to dissolve rutile silk), there is much less than can be accomplished as compared to relatively higher temperatures.

For the vast majority of this time, other labs were letting such stones go as: No indications of heating. But more recently, labs such as GIA, SSEF, Gubelin, Lotus, etc. have been working on this topic and so are overall in a better position now to recognize stones heated in this manner. The main question is how are they handling stones that were given a 'No indications..' report previously, when they are resubmitted now?

In theory, reports are only valid for the criterion/knowledge of the date issued and so such reports and conclusions should be updated. However, there can also be big numbers associated with the difference between stones that were sold as 'unheated' and now receiving a 'heated' determination. Thus complicating the matter significantly.

This was why I preferred to have the difficult conversations with clients upfront regarding low temperature heated stones, even when other labs were letting them pass because they didn't yet have the criterion to recognize them.

Best regards to all, be well and stay healthy!
Christopher P. Smith


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