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Lapidary / Gemstone Community Forum
December 10, 2018, 09:10:23 pm
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Bubbles in facetted Tanzanite

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Author Topic: Bubbles in facetted Tanzanite  (Read 568 times)
DavidS
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« on: February 19, 2014, 10:13:53 am »

 help  Can real Tanzanite have bubble(s)?    I found a gemstone listed as Tanzanite, and the price seemed about right since it wasn't the ideal deep blue / purple tones. Nonetheless, it arrived today and looking through a loop I noticed there are at least 2-3 bubbles.  BTW, this is a cushion cut, approx 11mm x 11mm.   

-David

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lithicbeads
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« Reply #1 on: February 19, 2014, 11:02:40 am »

Tanzanite is almost always heat treated and the bubbles would be an unwanted side effect of the heat treatment .
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gemfeller
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« Reply #2 on: February 19, 2014, 11:48:41 am »

David, are they actual bubbles?  The term "bubble" is widely and incorrectly used to identify other types of inclusions and I want to be sure we're on the same page.

Gas bubbles in transparent gems are usually a sign of synthetics or imitations like glass.  There should be no bubbles in natural crystals like zoisite var. Tanzanite, even after the mild heating it undergoes.  There are now quite a few Tanzanite simulants and substitutes on the market including glass imitations. 
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guest787
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« Reply #3 on: February 19, 2014, 12:41:48 pm »

I'm in agreement here.  If you have actual bubbles the stone might not be real.  On the other hand I have seen some faceted stones with inclusions in them that look like tiny air bubbles until you get them under strong magnification and then you discover they are natural inclusions.  If you have the ability to have someone else look at the stone and give you an opinion after examining it themselves, I would certainly do it.  Back east I had a jeweler friend who could stick a stone into this machine, turn it on with some sort of light and using it he could tell if the stone was real or not doe to the light refraction index it created.  Quite the handy tool.
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DavidS
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« Reply #4 on: February 19, 2014, 07:13:25 pm »

Everyone, thanks for your responses!  I found a local jeweler with an on-site GIA certified gemologist who, to my surprise, was the epitome of helpful.  Even though I had my three little boys (running around like they just slammed a red-bull) the guy brought out all kinds of equipment, examples & case study data from the GIA and then started to bring me up to speed on the situation.

In my own words, bubbles can be interpreted as either true gas bubbles or a spherical inclusion that may resemble a bubble. To the professional, the visual inspection was more than enough,  but he continued to show how other methods/equipment could provide further and more specific details.  Other tests revealed the stone was glass based with a mix, coating and/or fill of plastic or resin-like substance.   

For what its worth, the faceting work was quite nice and even received compliments....which would have been fine if the seller had disclosed the actual material used to create the gem.

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DavidS
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« Reply #5 on: February 19, 2014, 07:18:37 pm »

Also...magnification was another factor.  My loop is not that powerful or illuminated.  On the other hand, the gemologist had a real nice microscope with lighted base and HD camera hookup that could be displayed on a 60" TV.    Hmmmmm, now to find a way to add that to my collection =)

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guest787
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« Reply #6 on: February 19, 2014, 08:41:12 pm »

I hope you didn't pay a lot for that stone.  I'm glad you got someone to verify it's authenticity for you.  Would you be able to get your money back from the seller?
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gemfeller
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« Reply #7 on: February 19, 2014, 09:34:06 pm »

In my own words, bubbles can be interpreted as either true gas bubbles or a spherical inclusion that may resemble a bubble. To the professional, the visual inspection was more than enough,  but he continued to show how other methods/equipment could provide further and more specific details.  Other tests revealed the stone was glass based with a mix, coating and/or fill of plastic or resin-like substance.   

David, I'm glad you got professional help.  Some of those "bubbles" you mention could be 2-phase or 3-phase inclusions filled with liquid and gas bubbles as well as solid materials sometimes (3-phase.)  With low magnification they can trick the eye.  That's why the microscope is a gemologist's first and most useful tool.

I don't know exactly what your stone is but I suspect the answer may be more obvious: probably one of the spinel/lead glass doublets that have been coming out of Thailand and China lately.  It's possible what  you saw were simply air bubbles in the adhesive between the spinel and glass.  The glass could also contain actual gas bubbles.

Raise hell with the supplier.  There are plenty of legitimate dealers who want to see the scammers put out of business.

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vitzitziltecpatl
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« Reply #8 on: February 20, 2014, 06:47:35 am »

Interesting but depressing thread. Too many fakes and fakers out there in the world.

We don't have a microscope either, but sometimes just using a 10X loupe while wearing a visor gives enough extra magnification to help see some inclusions and such. Not ideal, but sometimes worth the effort if that's all you have on hand.
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DavidS
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« Reply #9 on: February 20, 2014, 09:39:02 am »

To let the seller have an "out", I told the seller his/her supplier must have made a mistake and that when I took the stone to a member of the GIA, they provided a full report stating the material was not Tanzanite.  Seller said they will  issue a full refund.

The most effective lesson here was being able to see and compare this stones bubbles to real inclusions.  Here's the thing, discussing the verification of an item, whether its lapidary, automotive, medical, or anything else, is really difficult to qualify until you have an equal size/shape/model reference in which to compare.   
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guest787
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« Reply #10 on: February 20, 2014, 01:27:30 pm »

Well to the seller's credit they are issuing you a refund, that at least gives them a little more credibility.  It is possible they got them from someone who sold them fakes telling them they were real.  Wouldn't be the first time it's happened.
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