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 Post subject: Re: Spodumene Investigation
PostPosted: Sat Jan 23, 2021 6:51 am 
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TheL wrote:
Good day all,
Would love to reopen this thread and ask a couple of questions to all you experienced gemos.

I have just finished cutting material very similar to Stephens Afghan material shown above. It does seem to be stable(several days in the sun), it is from afghanistan(as per the Afghani seller of the rough), and it DOES fluoresce(pink-orange).
Now here is the question, if this was colored by Chromium it would NOT fluoresce correct?
The color under natural light and under UV light is very very similar to some top colored merelani Mint Garnets.

So my assumption is that the chromophore for this material is Vanadium (my fav!) and hence the fluor and the stableness of the material?

what you all think? how can I test the theory myself if at all?


Some photos to put some visuals into my question above

Attachment:
hiddeniteMerelaniRough_small.jpg
hiddeniteMerelaniRough_small.jpg [ 79.91 KiB | Viewed 1260 times ]

left Afghan Spodumene(Hiddenite) Right Grossular Tanzania(Merelani Mint) Daylight

Attachment:
hiddeniteMerelaniRoughUV_small.jpg
hiddeniteMerelaniRoughUV_small.jpg [ 112.38 KiB | Viewed 1260 times ]

left Afghan Spodumene(Hiddenite) Right Grossular Tanzania(Merelani Mint) UV Laser from Upper screen left down crossing both crystals

Both colored by Vanadium?

Attachment:
hiddenite2.6_Small.jpg
hiddenite2.6_Small.jpg [ 170.14 KiB | Viewed 1260 times ]

Afghan Spodumene(Hiddenite) 2.6carat Modified varXcusion VanSant design
First time cutting this mineral. If i wouldnt have liked the result, I would never cut spodumene again!! what a nightmare...
Do find it so discouraging to see all those inclusion so prominently... it is a lot more sparkly, firey and clean in real life :(


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 Post subject: Re: Spodumene Investigation
PostPosted: Sat Jan 23, 2021 4:05 pm 
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Location: North Carolina
Looks like the real deal anyway. If you have a raman handy there's an extra peak added by chromium. Not sure what's up with the fluorescence. As I understand it pretty much all hiddenite has chromium and vanadium both.

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 Post subject: Re: Spodumene Investigation
PostPosted: Sat Jan 23, 2021 8:08 pm 
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Heya Stephen,
Yes fluorescence is what is got me a bit confused. I re-read about metal activators and remind myself about Chromium IS an activator and causes fluorescence. For some reason I thought it inhibit it.
So the question is, what is inhibiting the fluorescence on similar "hiddenites" from other locations?

ahh... found this

"Unlike chromium, vanadium does not cause red fluorescence, and gems colored green primarily by vanadium rather than chromium can sometimes be distinguished by a lack of red fluorescence. High concentrations of vanadium relative to chromium actually quench chromium fluorescence."
https://www.gemstonemagnetism.com/fluor ... etism.html

so perhaps my "hiddenite" is mostly colored by chromium when others that do not fluoresce are mostly colored by vanadium. Wish I had a way to measure amounts from different elements!

Am really only guessing unfortunately, unless tested properly. The site above ha info that keeps me wondering what really is giving the hiddenite I cut its color and fluorescence

"The activator manganese (Mn2+) along with a co-activator such as lead can cause orangey pink fluorescence in colorless Spodumene and pink Spodumene, also known as Kunzite. Both are diamagnetic. Manganese (Mn2+) by itself can create yellow/ fluorescence in some gems, particularly under short wave UV light."

"At times, more than one activator may be responsible for fluorescence within a single gem, as we find in some synthetic Spinels (see Spinel pg.5). As another example, the weakly magnetic colorless “Leuco” Grossular Garnet pictured below fluoresces orangey pink due to a combination of chromium and manganese. Chromium acts as an activator and not a chromophore in this natural gemstone, causing pink fluorescence under long wave UV light. The manganese activator reveals itself as orange fluorescence when the gem is viewed with a blue laser, and as yellowish green fluorescence under short wave UV light."


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 Post subject: Re: Spodumene Investigation
PostPosted: Sun Jan 24, 2021 3:01 pm 
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That is a FANTASTIC stone!!
I would love to have one like that.
Love the color!


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 Post subject: Re: Spodumene Investigation
PostPosted: Tue Jan 26, 2021 11:10 pm 
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ohh I very much appreciate the comment dChallener

it was very frustrating cutting it I tell you that much. kept hearing that ice breaking sound throughout the whole process, kept chasing cleavage problems, deciding which ones to leave or cut out, knowing it just kept getting smaller :( at then end i was happy, even if the camera is unforgiving.


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 Post subject: Re: Spodumene Investigation
PostPosted: Tue Aug 10, 2021 7:40 am 
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Finish Cutting another one of these. I think am getting a handle on this material... I think.

Tt doesn't like stress of any kind as most know, whether it be speed, pressure, grit size above 600. However, just as important, I also found that changing lap direction greatly
helps avoid or make issues worse. Specially at avoiding fractures from happening. Whenever a small fracture appeared, it would keep getting bigger unless I change lap direction.
There was a thread talking about this somewhere on the nets, it talked about reading the "grain" of the crystal as it is getting cut.
When cutting (not polishing) If the facet starts developing a shinny surface and it fights the lap and cutting slows then stop and change directions, otherwise cracks will start developing.

Anyway this is very similar to the previous stone above but cut down the minty axis. Where as the one above was cut down the Slightly yellowish green axis.
Using a modified Graham King Beryl design.
Color is a bit more saturated than the photo and shows a lot more dispersion. Gonna try to rephotograph.

Attachment:
IMG_0032Small.jpg
IMG_0032Small.jpg [ 330.82 KiB | Viewed 845 times ]


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 Post subject: Re: Spodumene Investigation
PostPosted: Tue Aug 10, 2021 9:58 am 
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Attachment:
IMG_0032Small.jpg


Again, a very nice stone! I really like hiddenite. Hard to get cut stones like this.


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 Post subject: Re: Spodumene Investigation
PostPosted: Wed Aug 11, 2021 6:46 am 
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Thanks DChanellener!
Spodumene becomes one of my favorites too, once cut. During cutting not so much!
Am thinking of sending this one to GIA or more likely AGL for a prestige report. Does anyone know if there will
be any word on this having chromium and being color stable in the report? (this is defs color stable, and fluoresces red
both good signs when it comes to green spodumene, but it is not from hiddenite but from Afghan origin)

Anyway, Will try to get a video next to try and capture the dispersion in full glory, so far all the photos I take come short.

Here is the latest photograph trying to get dispersion and the sense of the multiple secondary and tertiary reflections
that make it so sparkly and interesting, but alas... fail. We need new binocular cameras developed that are closer
to our eyes/brain to fully capture the life in gems!

Attachment:
hiddenite01Small.jpg
hiddenite01Small.jpg [ 455.19 KiB | Viewed 812 times ]


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