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 Post subject: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 5:33 am 
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Hi!
I would be most grateful for a first, second, third and fourth opinion on these inclusions.
These stones are set in a ring, 18K gold shank with silver mounting. The small white stone in the middle is a white sapphire. The shank has been remade sometime in the 1940s, judging from the gold hallmark. I believe the ring itself was made in the beginning of the 1900s. Please correct me, if I am wrong.
Like the amateur that I am, I have been trying to identify these stones for some time now. I have searched the internet for methods I could preform at home. I have looked them with a USB microscope, LWUV light, a diamond tester and tested them for a magnetic reaction. I even bought a refractometer. These are my results:
LWUV: strong pink reaction, even in daylight as you can see.
Magnetism: When placed on a piece styrofoam in water the stones are clearly attracted to the magnet.
RI: ca 1.721
USB microscope: Hand held digital up to 800X. I apologize for the poor quality of the pictures...


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File comment: This is visible without loupe, looks like a very thin scratch on the table of one of the stones. ca 4 mm.
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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 2:14 pm 
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Did not realize I was limited to 5 pics. Hope its ok to do this! And I have more..


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Last edited by Lunacur on Sat Mar 14, 2020 7:18 pm, edited 2 times in total.
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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 2:59 pm 
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Location: San Francisco
Synthetic, flame fusion spinel is fairly easy to identify.
Refractive index: natural spinel: 1.718 +.017/-.008 and synthetic:1.728 +.012/-.008
Polariscope: singly refractive, often with a cross-hatching effect.
LW and SW UV light: very highly fluorescent, stronger with SW.


Sidebar: the stones in question do not look original to the ring. How did you identify sapphire for the center stone? Can you post a picture of the hallmarks, maker's marks, quality stamps?

Thanks


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 4:08 pm 
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Thank you for your replay!

I have read that synthetic spinel shows a stronger reaction to SWUV. These stones react very strongly to LWUV and the inclusions have puzzled. Are the characteristic for flame fusion spinel or are they an indication of a natural stone?

I did not identify the small stone myself, I took it to a jeweler who said "white sapphire and aquamarine". However I have yet to find any account of an aquamarine that shows this reaction to LWUV.

If you don´t mind, why don´t you think the stones are original?

Thank you again!
/Beatrice


Last edited by Lunacur on Sat Mar 14, 2020 7:18 pm, edited 1 time in total.

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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 8:00 pm 
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Lunacur wrote:
I did not identify the small stone myself, I took it to a jeweler who said "white sapphire and aquamarine". However I have yet to find any account of an aquamarine that shows this reaction to LWUV.

Regrettably many jewelers don't know the first thing about gem ID. They will sometimes misuse the right tools, use unsuitable tools or just guess based on appearance. You can be dead sure with this reaction to UV that it's not aquamarine.

_________________
Rough and cut classic and exotic synthetic gems:https://store.turtleshoard.com


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Sun Feb 09, 2020 10:03 pm 
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It's synthetic spinel.


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Mon Feb 10, 2020 2:36 am 
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Stephen Challener wrote:
Lunacur wrote:
I did not identify the small stone myself, I took it to a jeweler who said "white sapphire and aquamarine". However I have yet to find any account of an aquamarine that shows this reaction to LWUV.

Regrettably many jewelers don't know the first thing about gem ID. They will sometimes misuse the right tools, use unsuitable tools or just guess based on appearance. You can be dead sure with this reaction to UV that it's not aquamarine.


Thanks!
Yes that was my thought too.


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Mon Feb 10, 2020 3:08 am 
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Thank you Barbra!
Good too know! Is that because of the stones reaction to LWUV? And does that mean that the different inclusions I have shown are gas bubbles? Perhaps you could shed some light on what this brownish "crystal" and these needle like things are?
I´m sorry for all the questions but I have been wondering about this for a long time now.

(and sorry for the grammar, English is not my first language)


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Fri Feb 07 07-22-01.jpg
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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Mon Feb 10, 2020 3:39 pm 
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I based very little on your inclusion photos, although some of the shots appear to have curved growth lines.
The LWUV was telling...if you have access to SWUV, the fluorescence will be chalky yellow.

A refractometer is the instrument I would rely on for this ID.


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Mon Feb 10, 2020 3:46 pm 
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Thank you so much!

I will get myself a SWUV. :)


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Tue Feb 11, 2020 1:32 pm 
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I'd spend my money on a refractometer. Just sayin'


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Tue Feb 11, 2020 1:39 pm 
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I'd spend my money on more lab equipment and the education to use them properly.

Nothing more dangerous than a 1/2 complete gem ID.


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Tue Feb 11, 2020 2:17 pm 
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Barbra Voltaire, FGG wrote:
I'd spend my money on a refractometer. Just sayin'


I did, and this is what I got. The shadow line is just below 1.72, so I would say 1.721. However I feel a bit unsure since I do not have lot of experience whit a refractometer. On top of this, the stones are mounted at an angle and to be able to get a reading I have to hold it in place. Does it affect the result if I put too much pressure on the stone?

(it was very difficult to get a picture, the line is much sharper and straight when I don`t have to focus the camera at same time as holding the stone in place)


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Thu Feb 13, 2020 4:07 pm 
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Right RI for synthetic spinel.


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 Post subject: Re: Synthetic flame fusion spinel?
PostPosted: Fri Feb 14, 2020 4:18 am 
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Thanks Isi!
What puzzles me is that it also seems to be the "right" RI for natural spinel. I have been doing some research since my first post and regarding RI for flame fusion spinel. It seems the most common opinion is that RI is 1.727 or slightly higher. But no definite ID.

I also read that blue flame fusion spinel is typically colored by cobalt (and not iron as natural spinel) which makes them diamagnetic. My stones show a clear reaction to a magnet which indicates the presence of iron.
According to Gemstonemagnetism.com some flame fusion spinels of a light blue color show a weak pink reaction to LWUV due to a low cobalt content. My stones have a strong pink reaction due to, as I understand, it either high cobalt content or chromium or a combination of the two.

I don´t have a polariscope but I did make a 2 home versions. One with sunglasses and a LCD computer screen and one with a small light and the 2 lenses. The stones remained dark, no tabby extinction. However I don´t know how reliable my tests are... So still no ID.
Which brings me back to my first post..

Would someone with experience please have an opinion and comment on the inclusions I have seen in the stones. Are they characteristic for flame fusion or natural spinel?


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