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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 4:05 am 
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Stephen Challener wrote:
Wow, that is excellent! Would Luc Yen actually command a premium over those? I would guess not but couldn't say for sure.


We priced them the same way, as in our opinion they are as rare and beautiful as the fine Luc Yen stones.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 6:11 am 
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Just a little over 2 ct - perfect clarity and cutting...

Difficult to find a Luc Yen one - think these Sri Lanka stones are much rarer - I hunt them for years.

This one was out of my range unfortunately. But so beautiful.

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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 8:07 am 
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Marlow wrote:
Just a little over 2 ct - perfect clarity and cutting...

Difficult to find a Luc Yen one - think these Sri Lanka stones are much rarer - I hunt them for years.

This one was out of my range unfortunately. But so beautiful.

Here's a couple on the market now. The larger one has better color in my opinion.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 8:58 am 
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I actually like the color of this non cobalt stone over the 2 cobalt's I posted earlier. The Lotus report has it as a medium tone which is a big positive with these Sri Lankan stones almost always being dark. From what I understand the cobalt content of the Sri Lankan material is much lower than the Vietnam's. Also like the much lower price.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 9:37 am 
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Problem in the Sri Lanka Cobalt spinel is that they are mostly cobaltoferrous spinel.

You get the vivid or purer blue only with a low iron content. And this is extremely rare in Sri Lanka spinel - not only in the blue ones.

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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 4:11 pm 
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I really love cobalt blue in everything from flow blue china to the wonderful blue spinels in this thread. But the ones with a color change/shift from blue in natural light to violet in incandescent really make me wonder. They change color in the normal way just like sapphire and seem to lie in the same part of the color wheel as cuprian/paraiba tourmaline. So why is the cuprian tourmaline that I got from Mozambique have a reverse color change, violet in natural light and blue/blue green in incandescent light? I have been trying to get research done on the unheated cuprian tourmaline I have come to call Laurellite (It is a new variety of Elbaite) for over 10 years with little success, after its original discovery.

I would greatly appreciate getting to see an absorption graph of a spinel color changer or borrow a sample so I can examine it with my spectrometer. Laurellite grows rarer every day since it can be heated to that pariaba blue and I am not getting any younger so the research needs to be done.

Bruce


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 4:57 pm 
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The color changer have a much lower cobalt content than the saturated vivid blue ones

https://www.ssef.ch/wp-content/uploads/ ... TE2014.pdf

page 13-14

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The color changing material ( Vietnam and Sri Lanka) compared to Vietnam Cobaltspinel

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Vietnam cobaltspinel compared with Sri Lanka cobaltoferrous Spinel (the dark blue oval has the strongest cobalt spectrum )

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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Sat Sep 29, 2018 5:10 pm 
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Stone on the left and right are from Vietnam - stone in the middle is per vendor from Sri Lanka ( unfortunately a larger iron stain) and the price was quite low compared to the vietnamese material so it wouldn’t make sense to import a rough one from Vietnam for a Sri Lankan dealer and sell for a low price. Who knows...

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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Tue Oct 09, 2018 1:45 pm 
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Blue comparison. Cobalt spinel, Ceylon, Burma and Kashmir sapphire.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Fri Mar 22, 2019 2:37 pm 
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This 2.5 ct Vietnam cobalt must be going for a few bucks?


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Mon Mar 25, 2019 3:55 am 
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Nicky Newark wrote:
This 2.5 ct Vietnam cobalt must be going for a few bucks?


For sure. And the Sri Lankan material as well.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Tue Apr 23, 2019 10:54 pm 
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If you were wondering about the top cobalt spinel prices nowadays:
http://www.preciousgemstones.com/gfspring19.html

That one is a new record as far as I know. I've seen 25, 30 and even 50k USD per carat before, but not 60k. Well, it was only a matter of time as the material gets more in demand while the production is low.


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Wed Apr 24, 2019 10:45 am 
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Dioptase wrote:
If you were wondering about the top cobalt spinel prices nowadays:
http://www.preciousgemstones.com/gfspring19.html

That one is a new record as far as I know. I've seen 25, 30 and even 50k USD per carat before, but not 60k. Well, it was only a matter of time as the material gets more in demand while the production is low.


I saw that stone at AGTA in Tucson this year and spent some time drooling over it. It was certainly the nicest example that I have personally seen. When I came back later to show it to a colleague, they had pulled it from the case and the owner told me that they were in negotiations to sell. I did not find out what the final price ended up at, but I'm sure it was significant. :D

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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Wed Apr 24, 2019 10:24 pm 
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I have never seen the spinel in person, but it seems to have a beautiful color in photographs. I think it seems to be following a similar path of Paraiba tourmaline, another rare beautiful gem. A path that takes it out of the normal trade world into the very limited rarefied world of private collections and museums. I have search high and low for transactions that involve top grade Paraiba tourmaline. I think that hens teeth are more common. Yes The Guide has prices for top grade Paraiba in less than 3 carat sizes, but my feeling is that the price of a pure,well cut and glowing cyan Paraiba tourmaline (from Paraiba) in a 2.99 carat size would be negotiated (like the spinel) and not set by the market because there are not enough transactions to establish a price. By their nature negotiated purchases are erratic and volatile. And insulated from the great power of the trade to develop demand for a gemstone. If you don't have any product to sell who will spend resources to promote it? I personally think that the discovery of larger quantities of paraiba type material in Mozambique has helped push Paraiba into the realm of being a precious gemstone. Without similar support for the spinel ( reasonable availability) prices will not have the same price pressure that Paraiba has and will subside. Or at least not be more than a WOW factor to most people. Paraiba tourmaline as the sum of all the material from all locations (no one sells paraiba type material now) is truly blessed and I hope the spinel does not remain too rare.

Bruce


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 Post subject: Re: Luc Yen cobalt blue spinel.
PostPosted: Thu Apr 25, 2019 1:10 am 
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Perhaps the recent find in canada will end up being significant enough to impress the market.

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