Origin of Emeralds

[pyramid]

Is it correct to assume that if there are any black inclusions in an emerald that it cannot be of Columbian origin?

It is probably more complicated than this but this is what I was told by a layperson.

 

[mogok]

Hello Pyramid!
You are right: Its more complicated than that.

Traditional inclusions in Colombian emeralds are 3 phases inclusions with a jagged form.
You can find these inclusions in the stones from the 2 main colombian deposits: Chivor and Muzo.
But in Chivor emeralds you can find in association with these "3 phases" some pyrite inclusions that can very easily looks black...
So a black inclusion cannot proof that the stone is not colombian. It can be a good indication that the emerald is colombian from Chivor if it is associated with the "3 phases". On the other side small rhombohedric calcite inclusion along with the 3 phases are usualy seen as Muzo, colombian origin.

Anyway other kind of black inclusions can be found both in Muzo and Chivor.

Origin determination is a very difficult task... Microscopic observation can give indication but only god knows where a stone in front... And god is not as easy speaking as me!

lol

Hoping to have helped you!

 

[mogok]

Here are somes pics I did with my microscope that show typical "3 phases" inclusions from a colombian emerald.
You can see inside the jagged fluid film one round gazeous phase and a small squarish solid crystal.

The second photo for information was taken at 80X the 3 other ones at 40X.

All the best,

 

[mike04456]

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On 1/23/2004 12:09:35 PM pyramid wrote:





Is it correct to assume that if there are any black inclusions in an emerald that it cannot be of Columbian origin?

It is probably more complicated than this but this is what I was told by a layperson.
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Science is frequently messy; there are few absolutes in the gem world. Many times when the conventional wisdom has accepted that some gem material only occurs one way or in one place, someone will find a sample that upends all those assumptions.

Mogok: great photos. Those 3-phase inclusions are always fascinating.

 

[pyramid]

Thank you for your replies mogok and LawGem. The photos are very interesting. I will have to have a better look at my emerald under magnification.

 

[mogok]

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On 1/23/2004 1:35:35 PM LawGem wrote:





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Science is frequently messy; there are few absolutes in the gem world. Many times when the conventional wisdom has accepted that some gem material only occurs one way or in one place, someone will find a sample that upends all those assumptions.

>----------------[/quote]


Exact LawGem,

I remember to have been bluffed by my gemology teacher in Burma several years ago. About the common sense to say that "If there are 3 phases inclusions, in an emerald so its colombian stone": We were having fun with emeralds origin and she had in her gem box along with several emeralds this tiny little green piece of nothing in the box that I discovered after checking 6 or 6 emeralds. We were watching the stones under microscope too lazy to use any other instrument to identify this green staff. The tiny little green thing had several very nice but low relief 3 phases inclusions... So naturally I gave this stone the following identification be cause of the famous 3 phases: Colombian emerald!

Well the stone was not Colombian... It was not even an emerald... It was green fluorite!

It was a good lesson about certitudes and bad habit in gem testing!

 

[mogok]

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On 1/23/2004 12:09:35 PM pyramid wrote:

Is it correct to assume that if there are any black inclusions in an emerald that it cannot be of Columbian origin?----------------

Hello Pyramid,

I have finally found a photo of pyrite crystal inclusion in in a chivor emerald. I get it from geminterest.com (Fiendly French gemology website with amazing content)
Here the crystals are quite shiny but pyrite can also looks more blackish especially depending on the lighting conditions you use to look inside the stone. The photo I present here to you guys was taken using dark field illumination with a microscope... I you are using a loupe or bright field illumination then these pyrite crystal may probably appear black...

 

[pyramid]

mogok Thank you again for following this up.