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PostPosted: Tue Aug 04, 2009 10:51 pm 
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Is it useable?
but there again. with your nifty cuts you could make anything.

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PostPosted: Wed Aug 05, 2009 12:52 am 
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johnddyer wrote:

Somewhat interesting, never had natural untreated blue topaz before, what do people think?



It looks right for what it is claimed, that is to say similar to specimens I am used to. Obviously, a very fine one.

I wonder whether once cut this will not turn into a pile of 'blue topaz'... Even if coming out of your hands the stones may not have any trouble upholding their identity as a rare natural color, it seems reasonable to think that, at some point down the road of private ownership... the spoiled reputation of the treated will eventually catch up with them even in Texas. Perhaps it would take too long, passing though too many 'hands' for this to happen and as such the issue is of little relevance now, but...

For the reason above, I am inclined to wish a happy life in a fine gem minerals collection, to this stone. Or else, if those impressive crystal faces and the transparent line of sight down to the pool of blue inside... fail to impress in due time, a great carver's hand that would preserve its identity. If worse comes to worse and this gets to be treated as 'rough', fingers crossed that some of the finer jewels should end up with a journalist! 8)

OK. had to be said; hoping to hear I'm wrong...

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PostPosted: Wed Aug 05, 2009 1:05 am 
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Well said.

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PostPosted: Wed Aug 05, 2009 1:30 am 
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Hello John,

I have a couple of large chunks of Siberian blue, certainly not as deep or saturated a hue and quite a bit zoned. Both are 7+ cm x 9+ cm x 3+ cm. I acquired them many years ago as a gift because as Valeria has pointed out, once cut there is no provenance. When treated blue topaz arrived, the mine became worthless.

As far as I can tell the miniscule portion of the population that is interested in acquiring natural blue Topaz are going to do so in Texas or Australia.

Tony.

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PostPosted: Wed Aug 05, 2009 7:45 am 
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All interesting comments, I must confess though that in almost all cases I see minerals as rough that can be made into a beautiful gem!

Provenance could be somewhat established photographically I think although it would be more work.

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PostPosted: Wed Aug 05, 2009 12:16 pm 
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Well John..any Tom, Dick, and Harry can slap facets on a stone but to have mother nature do it..well..thats a different story..it just amazes me that natural occurances can have such mathematical qualities with straight lines and corresponding angles...that sucker will sit so much better in a mineral collection...I have to agree with Valeria's point..once cut it just disappears into the throng of cut stones out there(generally speaking as there will always be small discepancies between every cut stone) but left as is there is nothing else like it in the world but like you said when you see any stone in natural form you see the finished product..LOL.. of course, I on the other hand, see it for what it is as a gem in natural form :D

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PostPosted: Wed Aug 05, 2009 11:23 pm 
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For laughs: Russian natural blue topaz has the wildest reputation... [REF: AMNH] & [REF: Glacier]. Might as well run for office.



johnddyer wrote:
Provenance could be somewhat established photographically I think although it would be more work.


I believe this has been done for other materials, a matter of: get report, cut a bit, get another report, cut some more, etc. At the very least the part about piling reports sounds silly enough. Strike off third party intervention, and... does the lot sound any more conclusive then a signature?

Would certainly enjoy a pile of slides documenting your work process, only for entirely different reasons.

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PostPosted: Thu Aug 06, 2009 7:09 am 
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Just an interesting note, if you recall the origins of the post - Gemselect has now removed the "imperial"topaz from their site. It's been totally stripped clean of it.


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PostPosted: Thu Aug 06, 2009 7:25 am 
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:shock: i went to check it out for myself, and even tried a search on gemselect for "imperial topaz," robert, which resulted without any imperial topaz to be found on the website. go figure, lol!! :wink:


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PostPosted: Thu Aug 06, 2009 10:25 am 
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Yup, there's NOTHING. It's been "wiped." :shock:


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PostPosted: Thu Sep 17, 2009 4:35 pm 
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I am a little surprised by this discussion of imperial topaz.

No one has mentioned that the internal structure of real imperial topaz is quite different from common topaz. I don't have the technical vocabulary to describe it, but I can tell you what it does.

First, imperial topaz comes only from Minas Gerais in the region near the city of Ouro Preto. Minas Gerais is a very large state, comprising an area about 50% larger than the state of California, just to give you an idea.

The crystals are usually quite small in comparison to common topaz.

Unlike common topaz, their internal structure contains many tiny fractures. Thus, while cutting and polishing an imperial topaz, great care must be taken or it will break. And, sometimes these fractures are large enough to permit the polishing material to enter.

As already mentioned above, the crystal's color will intensify when looked at through the c-axis.

But the main difference is something called in Portuguese "brilho de fogo," or "brilliance of fire."

Imperial topaz has a special way of reflecting light that causes it to shimmer.

Anyone who has actually seen real imperial topaz of even moderate quality will have seen this shimmer. It is somewhat similar to a schiller effect, but much finer, and is extremely difficult to photograph, although I have come close even with my little amateur cameras.

Imperial topaz is defined by these special small shimmering crystals with internal fractures, and so far as I know, the only region where they are found is in Minas Gerais.

As to color: imperial topaz comes in colors from a weak pale yellow to a better gold, to slightly orange, to salmon, to sherry and on along this sort of spectrum -- but they are all imperial topazes.

The difference is in the prices that are paid for these colors.

Some are heated to become pinkish. Lavender is a highly desired but rare color.

Nowadays, some are irradiated, but this is usually discernible because the colors have an intensity and tone that are not natural.

Generally, imperial topaz cannot be cut in the same way as common topaz due to the breakage problem. Thus, there are traditional cuts specific for imperial topaz.

I have seen irradiated citrines and low-quality rubilites cut in these imperial topaz cuts and hawked as imperial topaz.

Five years ago or more, common topaz from the Khatlang province of Pakistan was being irradiated, and this process produced a very strong coppery orange shimmer, which unfortunately faded over time. It was noticeable that the shimmer effect was not nearly so fine. Nevertheless, these stones were often quite pretty.

The producers of this irradiated topaz did not bother to have it cut in the traditional cutting styles of real imperial topaz.

Very often, the irradiation produced very easily discernible color zoning -- something I have never seen in real imperial topaz.

The color was usually an orange copper with grey and brown undertones.

Sizes could go up to 40-50 carats -- an almost unheard of size for real imperial topaz.

But the dead giveaway was the price.

Even the lowliest imperial topaz with a washed out orange salmon color would cost $12-$15 per carat in Teófilo Otoni.

Here is a link to a flickr album with photos of variously colored imperial topazes:

http://www.flickr.com/photos/dbprecious ... 84/detail/


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PostPosted: Thu Sep 17, 2009 5:06 pm 
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I have only once held a true imperial topaz in my hand. What I remember was that when looking into it it had, for want of a better description, a "watery" appearance. Very subtle, but there. Never have seen it since :?

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PostPosted: Thu Sep 17, 2009 8:54 pm 
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Hi, Morning Dove,

Hmmm, I dunno -- I can honestly say that I have never seen an imperial topaz with what I would have described as a watery look, but of course they may exist.


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PostPosted: Thu Sep 17, 2009 9:43 pm 
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Excellent info gringa..very well written and informative.. :)

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PostPosted: Thu Sep 17, 2009 10:32 pm 
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Thank you, amethystguy.

Speaking of amethysts -- here in Bahia and also in Minas Gerais there are some mines producing amethyst that has a really beautiful silvery shimmer. My best examples were sold (hitting myself for the rest of my natural born days), but this past April I picked up a new piece that is pretty neat (but impossible to photograph).


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