Accuracy of Origin Report ?

[MingmehDorji]

Hi,

How accurate are the Origin Reports in the Market ??? Some charge reasonable price but others extremely expensive.

And, labs that do not own any of those electron spectroscopes, could correctly identify Origin reports based on feelings and experience ?? Please educate me. Thanks.

Dorji.

 

[mogok]

Hello MingmehDorji,

This is a very difficult question that you are asking. I will try to bring you some answer element that other might comment. I hope then that you will be able to understand more clearly what origin reports are and what they worth, which is your question if I understand well.

Origin determination is one of the most difficult task a gemological laboratory can be asked about. Usually when you check a gemstone, the first step is to identify it correctly as let say a ruby or a spinel. This is a standart task for a gem lab. Then you have to determine if the stone is from natural or synthetic origin. In some cases it can already be tricky and some labs can already occasionaly make a mistake. Then you have to look if any treatment was apply to the gem... In this case it can be a challenge for example in the case of a small stone without inclusions...
Now asking about the geographical origin is possibly the ultimate challenge.

Origin determination is usually provided as an opinion by gemological laboratories. They look at the stone and compare the data collected from the stone with the other data they have from reference samples. Then they give their opinion. Some laboratories are specialized in this field and have invest a lot of time and money not only on instruments but also in collecting reliable samples from all the known sources of a given gemstone. This is a huge investment. Of course then the samples have to be studied with all the different instruments available in order to compare then the results with the information collected from the gem which was bring for examination.
This is why this service are expensive. Providing an origin opinion takes time from very experienced gemologists that have been expensive to bring to a level where they can give a good statement.

Usually a laboratory check a gem for origin he will study the gem with all the instruments available.
First tehy will look at the standart gemological fact about the gem: color, nature, Refractive index,...
Then they will study the gemstone internal world as the gemstone inclusions are akey to its geological past. And understanding the condition under which a gem was formed can give some serious information about where it could have been mined and where it could not.
Then possibly analysing the chemical composition which can be useful as trace elements can be different from one origin to an other one.
Analysing the gem color zoning, growth line stucture can help also to get an idea about the shape that the original crystal had. Here again as in different mines some shapes are more common than other, some indications can be found.
Analysing the different spectrums a gem might have using UV VIS, FTIR might also be useful,
and many other tests like using an electron microscope can also be useful... Anything can be usueful to my experience. Case by case an instrument will or will not provide an alement that can be useful to get an idea...

In fact after all these tests to be done in some cases an experience gemologist will be able to have a very good opinion about where this or that gem came from... In most case he will not be 100% sure as exceptions are common, but in some cases there are very high probabilities.

As origin is about opinion, any lab can give an origin opinion. Not everything will depend on the fact that you believe or not about this laboratory qualification to provide a reliable origin opinion.

Origin is as a result an opinion which is usually based on a very complete study of a given gem. It is nevertheless not a statement of quality as I said usually: You can get a beautiful sapphire from Madgascar or China and fish tank sapphires from Kashmir or Burma... So origin should not be look as something else than a romancing factor for a given gem.

I hope that the elements I gave you were useful.

All the best,

 

[Richard Sherwood]

Date: 9/8/2005 4:02:00 AM
Author:MingmehDorji

How accurate are the Origin Reports in the Market ??? Some charge reasonable price but others extremely expensive.

The origin reports are only as accurate as the gemologist (or gemologists) issuing the report. If he/she is a gemologist with advanced training, experience and equipment, then his/her opinion is more accurate than a gemologist without one or more of those factors.

Usually (but not always) the guys with more training, experience and equipment charge more than the guys without.

But then you have the issue of trade accepted credibility. Some labs have established a reputation for consistent country of origin determination with a high degree of accuracy. Dealers and the public tend to be more comfortable with their reports, and will pay more money for them. It makes the stone more credible, and more liquid.

For colored stone country of origin determination, the three labs whose opinion internationally carries the most weight are (in my opinion):

The Gubelin Lab in Basel, Switzerland
The AGL (American Gemological Laboratory) in NYC, headed by Cap Beesley
The AGTA lab (American Gem Trade Associaton laboratory) in NYC

The first two labs are pretty pricey, and used a lot for major stones. The AGTA is fairly reasonable, and used a lot by the trade and consumers alike.

I would also feel comfortable with a country of origin determination from the AIGS (Asian Institute of Gemological Sciences), by the way.

 

[Richard Sherwood]

Date: 9/8/2005 4:02:00 AM
Author:MingmehDorji

And, labs that do not own any of those electron spectroscopes, could correctly identify Origin reports based on feelings and experience ?? Please educate me. Thanks.

As Vincent points out, country of origin is often a difficult determination. Sometimes it''s simple, many times it''s not.

The instruments which are very helpful in this respect are the UV/VIS/NIR (ultra-violet, visible spectrum, near infra-red) spectrophotometer and the FT-IR (Fourier transmission, far infra-red) spectrophotometer. They make difficult determinations quite a bit easier. A gemologist who carries this equipment in his inventory is usually a pretty serious gemologist, whose opinion could conceivably carry more weight than a gemologist without it.

That said, there are many instances in which a gemologist with standard equipment and advanced training/experience could correctly identify country of origin. The key is more in the training and experience than in the equipment, although the best of both tends to create more widely accepted credibility.

An experienced dealer might be able to conclusively identify to his own satisfaction that a sapphire is from Burma with just a loupe, and feel comfortable enough to purchase the stone based on his experience. When it comes to selling it though, he''s usually going to want a report from a credible lab accompanying it. It makes the stone more liquid, and allows him to get the full premium for it.

The electron microscope is helpful sometimes, but veryyyyyyyyyyyyy expensive. Not many labs have this piece of equipment, because the price versus the enhanced capabilities it gives are usually not cost effective. It can give you an edge, but not really enough of an edge to shell out all the money for it.

I''d be curious if anyone knows which labs carry an electron microscope in their inventory, by the way.

 

[Richard Sherwood]

Date: 9/8/2005 8:09:55 AM
Author: Vincent Pardieu
In most case he will not be 100% sure as exceptions are common, but in some cases there are very high probabilities.

I agree with everything you said Vincent, with the possible exception of this statement.

It's not that I feel your statement is incorrect, but rather the perception it conveys of an opinion not being conclusive in the majority of cases, but rather only in the minority of cases.

I feel it's the other way around. In my opinion there in many cases (more than not) when a gemologist with advanced training, experience and instrumentation can conclusively identify country (or region) of origin, and in some cases even mine (or region of mines) origin.

In cases where it's impossible to conclusively identify a particular country of origin (like perhaps Thai versus Cambodia in the case of sapphire), even the determination that it is either Thai or Cambodian goes a long way in giving helpful information. In other words, by conclusively identifying that the stone is not Kashmir, not Sri Lankan, not Burma, not Madagascar, not Australian, not Brazilian, not Colombian, not African, not etc.....but either Thai or Cambodian, the gemologist gives information which is key in valuing the stone.

 

[mogok]

Hi Richard,

Well regarding to the point you dont agree with me I can give you some explanations. The example you have taken about Thailand or Cambodia is excellent as the ruby field in the east of Chanthaburi extend through the Thai Cambodian border. The stones share the same geologic origin and it is not possible to say if a stone is coming from this side or that side of the border...
Now in some cases, the term country of origin is disturbing. The fact is that in a country you can have several gem deposits in which gemstones were formed under completely different conditions. In the past there were few cases like that as there were usually for ruby and sapphire few mines: Rubies were from Burma or Thailand/Cambodia, sapphires from Kashmir, Burma, Sri Lanka, Cambodia, Australia mainly with some minor deposits that were already disturbing the country based differentiation.

Now for example in Kenya you can find in the south of the country at Mengare swamp near Tsavo some rubies formed under metamorphic conditions which at one time could be confused with some Burmese stones, but now Baringo area north of Nairobi produce some rubies from basaltic volcanic deposits which are close to the stones from Thai origin... So when you have a report with the origin: Kenya, you might still dont know which type of kenyan ruby you have here...
The same problem exist in Madagascar: There you find sapphires in the north near Ambondromifehy that are close to the stones found in Thailand, Australia, or Laos as they are green, blue or yellow basaltic type, and in the south near Andranondambo are produced gems that very close to some Burmese or Khasmir and finally in Ilakaka you have gems very close to the metasomatic gems found in Sri Lanka. So what does the origin "madagascar" mean for a sapphire?
Finally if in some countries you have some gem deposit which gems are presenting some homogeneity regarding to their properties like in Kashmir, you have in some countries some very complex deposits producing all colors. In Madagascar at Andilamena, sapphires can be found in all colors. In Tanzania gems from the Umba valley also present some huge difference regarding their chemical composition and aspect. It is also the same for the Mogok deposit in Burma...
The problem laboratory can face is that if for example they own a gem from a mine lets say in Mogok, there is no way to be sure that all the stones from this mine will have the same characteristics! Gems from one "pocket" can be different in several aspects from the gems that will be mined 100 meters from this pocket 5 years later. And these new gems can be closer to the reference gem from a deposit of the same geologic type in a different country...
So regarding to origin determination it is very difficult to be sure at 100%...
Personally I''m never...

As I''m not the guy that have taken the stone from the ground, I cannot be sure... But I can have an opinion.
This opinion can be different from the opinion of an other lab as this other lab have different reference samples and different identification techniques, or different instruments...
Sometimes when we are asked about origin we would like to give more than one possible origin, instead of one "most likely" probable origin. But well it does not look very serious to have a report with possible origin: Burma, Vietnam, Afghanistan or Nepal... But in fact rubies from marble deposits are found in all these 4 countries and if the stone is small and was heated, then things are not easy to differentiate between lets say: Mong Hsu, Luc Yen, Jagdalek or Chumar...

Now regarding the huge difference in terms of production between Mong Hsu and Chumar it is more likely the stone to come from Mong Hsu but well it is difficult to be sure at 100%...

I hope that these explanation will be helpful for you to understand better my point.

 

[Richard Sherwood]

I understand your dilemna Vincent, but would suggest that the scenarios you mention are easily handled in a way which gives the consumer the information they need and gives the stone it's full due.

First, for stones which don't have the possible conflicting countries of origins, it's possible to identify them conclusively through well known gemological characteristics. Kashmir sapphires would be a good example, or Sri Lankan sapphires. These stones usally have characteristics which allow positive ID.

With Colombian emeralds, for example, it is sometimes possible to determine whether the stones come from the Muzo or Chivor mine regions by their characteristics.

My point is that there are many stones which can be conclusively identified with a particular country, region, or even mine.

For those that can't (with identical characteristics), then they can be identified as a "type". This is what many labs are doing now with the "Paraiba type" designation for tourmalines with the exact same characteristics either from Paraiba or Nigeria.

You can identify a sapphire as being the "type" of sapphire which occurs in the Thai/Cambodian border region. This goes a long way towards telling a client what value level their sapphire will fall in. They know it will fall in the Thai "niche" for market level as opposed to the Kashmir, Burma, Sri Lankan, etc. "niche".

 

[MingmehDorji]

Thank you both gentlemen for the kind elaboration. Noted that electron Spectroscope are very expensive but most asian labs has them fully equiped already.

My questions lies with a lab that is not within the names you have mentioned, and has no advanced intrumentations.

Now, with those electron spectroscope (Raman, Edax, Ftir, EDXRF etc.), can a sample be feed in as a basic DNA of the mine ? Even a mine, next door or a mile away will not have the same composition (graphical chart) !!!! That''s the DNA of gemstones.

In human, if you get his father or anyone in the family, you could deduce his DNA identity.

So, question lies, why one still has to rely on human factors rather than sciencitic factors ??

Dorji.

 

[mogok]

Hi MingmehDorji,

I know many labs that does not have any "advanced instrument" but that have an "advanced gemologist" with a lot of knowledge about the stones from the area he is working in. I think the most advanced equipment a lab needs also to have a an "advanced gemologist" as an instrument, as good as it is, will never tell you anything else than numbers or graphs...

As an example I will trust without any problems several small burmese laboratories about a burmese gem. Even if they dont have any advanced equipement, they use their brain and their eyes much better that a young lets say french gemologist that have spend 8 years working on spectroscopes in a french university and that have never seen really outside his purely scientific point of view a gemstone.
For the best advanced instrument to be acurate and useful, there is a need for an "advanced gemologist"... And gemology is not only about science even if science if one of the best tool in the gemologic field.

In my opinion there is no DNA for gems, all gems are differents and gemological laboratories are only providing their opinions.

Now this is to the customer to feel good or not feel good with this or that laboratory opinion.

I hope that I was able to help you.

All the best,

 

[Richard Sherwood]

Date: 9/8/2005 11:31:52 PM
Author: MingmehDorji
Noted that electron Spectroscope are very expensive but most asian labs has them fully equiped already.

Now, with those electron spectroscope (Raman, Edax, Ftir, EDXRF etc.)....

Dorji, I think you're confusing two different categories of instruments. The instruments you mention above are all different types of advanced spectroscopic equipment. They are not an electron microscope.

Although expensive, they are nowhere near as expensive as an electron microscope. I doubt that most Asian labs have an electron microscope on hand. For example, I just tonight read an article in Gems & Gemology where GIA-GTL gemologists conducting a study on Zambian emeralds traveled to two different major universities to use their electron microscopes.

Raman= Photolumescent spectroscopy
Edax= Energy dispersive X-ray analysis spectroscopy
FTIR= Fourier transmission far infrared spectroscopy
EDXRF= Energy dispersive X-ray fluorescence spectroscopy

 

[Richard Sherwood]

I concur with Vincent''s example of why a human with "advanced" knowledge is necessary to interpret the results of "advanced" instrumentation.

I also know several experienced dealers whose "eye" I would put up against many gemologists with "advanced" equipment.

 

[rubydick]

Date: 9/8/2005 11:31:52 PM
Author: MingmehDorji
Thank you both gentlemen for the kind elaboration. Noted that electron Spectroscope are very expensive but most asian labs has them fully equiped already.

My questions lies with a lab that is not within the names you have mentioned, and has no advanced intrumentations.

Now, with those electron spectroscope (Raman, Edax, Ftir, EDXRF etc.), can a sample be feed in as a basic DNA of the mine ? Even a mine, next door or a mile away will not have the same composition (graphical chart) !!!! That's the DNA of gemstones.

In human, if you get his father or anyone in the family, you could deduce his DNA identity.

So, question lies, why one still has to rely on human factors rather than sciencitic factors ??

Dorji.

MingmehDorji,

What Vincent has stated in his various posts is so true. The most powerful gemological tool is that organ which resides behind a pair of human eyes. An experienced gemologist can do terrific things even with simple tools, while a beginner, even with the best-equipped lab, can often do little.

The tools used today to determine origin with ruby and sapphire are, in rough order of importance:

1. An experienced brain.
2. Gemological microscope with fiber-optic light, full set of filters, immersion tools, etc., all coupled to #1 above.

Every other tool available today pales in comparison to the importance of #1 and #2 above. The other tools include (again, in rough order of importance for corundum)

3. UV Lamp
4. Direct vision spectroscope
5. FTIR
6. UV-Vis/NIR spectrophotometer
7. EDAX
8. Raman spectrometer
9. Light element analysis tools such as SIMS, LA-ICP-MS and LIBS
10. Others such as PIXE, laser tomography, electron microscope, microprobe, etc.

Note that numbers 1-4 are found in virtually all gemological labs, big or small.

Regarding the DNA signature, the idea is nice, but it simply doesn't yet exist in gemstones.

The fact that certain gems are found in certain places by definition means that certain geological characteristics must be shared, otherwise the gems would not have formed in the first place.

Generally, it is possible for gemologists to determine with a high degree of certainty the rough geologic environment (basaltic, metamorphic, etc) a ruby or sapphire has formed in. But to try and take this further, to identify the specific location a gem came from, is far more difficult and much more error-prone.

Now there are certain areas of study that appear to have promise. Some success has been achieved in the realm of emerald origin by the use of advanced dating technologies (while it is not the same, think of it like carbon dating for artifacts). Since each deposit formed at a particular period in time, if one can identify the age of a gem, one can rule out certain other places. For example, while the sapphires of Kashmir and Sri Lanka may have formed in quite similar geologic environments, if they formed at different times, dating the specimen could provide a means of separation.

To the best of my knowledge, dating technologies do not yet exist for corundums, but perhaps some day...

In the meantime, origin determination remains an imperfect science.

So, in answer to your question, can a gemologist be accurate in origin calls, even if they do not have access to high-tech tools? If they are experienced, with the above caveats in mind, generally yes.

And will they be as accurate as an experienced gemologist working with high-tech tools? No, not as accurate (but the differences separating them are shockingly small).

Hope that clears things up a little bit

 

[Richard Sherwood]

This comment made by Cap Beesley of AGL in an interview by Robert Genis of Gemstone Forecaster is seven years old, but I thought it was interesting in regards to the country of origin discussion:

Beesley: "I would estimate 80% of all gemstones submitted to the lab receive a positive identification comment (based upon available gemological information, it is the opinion of the laboratory that the origin of this material would be classified as, for example, Classical Mogok Burma)."

 

[rubydick]

Date: 9/10/2005 11:52:04 AM
Author: Richard Sherwood
This comment made by Cap Beesley of AGL in an interview by Robert Genis of Gemstone Forecaster is seven years old, but I thought it was interesting in regards to the country of origin discussion:

Beesley: ''I would estimate 80% of all gemstones submitted to the lab receive a positive identification comment (based upon available gemological information, it is the opinion of the laboratory that the origin of this material would be classified as, for example, Classical Mogok Burma).''

Not sure if I understand what is meant by the term "positive identification comment." Positive is a relative term, particularly for a buyer vs. seller. And I''ve asked this question before: What the heck is "Classical Mogok Burma"?

 

[MingmehDorji]

HI,

With all these advanced electron spectroscopy, it is still not possible to perform the Gem DNA.

Isn't the human DNA testing hairs or tissues more complicated and they are also using an electron spectroscope ?

Dorji.

 

[rubydick]

Dorji,

Sadly, minerals do not possess DNA (deoxyribonucleic acid; DNA is a code used within cells to form proteins).

And as I mentioned in my previous post, electron microscopy is not that useful in origin determination of gems, thus most gemological labs do not possess this instrument.

 

[Richard Sherwood]

Date: 9/11/2005 10:03:19 PM
Author: Richard Hughes

Date: 9/10/2005 11:52:04 AM

Author: Richard Sherwood

This comment made by Cap Beesley of AGL in an interview by Robert Genis of Gemstone Forecaster is seven years old, but I thought it was interesting in regards to the country of origin discussion:


Beesley: 'I would estimate 80% of all gemstones submitted to the lab receive a positive identification comment (based upon available gemological information, it is the opinion of the laboratory that the origin of this material would be classified as, for example, Classical Mogok Burma).'

Not sure if I understand what is meant by the term 'positive identification comment.' Positive is a relative term, particularly for a buyer vs. seller. And I've asked this question before: What the heck is 'Classical Mogok Burma'?

I would interpret "positive identification" as meaning conclusive ID of origin.

"Classical Mogok Burma" I would interpret as "Classic Burma" ruby from "Mogok" area, to differentiate in particular from the relatively recent (non classic) Hmong Shu area.

How's the AGTA lab handling country of origin ID for ruby and sapphire? Do you give a "positive" or "conclusive" ID? If not conclusive, do you use a "confidence ranking" of some sort?

 

[Richard Sherwood]

I''m bumping this one up. Curious how AGTA handles country of origin ID''s.

 

[Richard Sherwood]

Still curious.