Gemstone identity Confusion (Please help)

Gem Related Discussion
1

Hi all,

I hope you are all keeping well. I wonder if anyone can please help me out here. As i mentioned a long time ago, i have some bluish/green tourmalines gemstones and was confused about it identity as to either Paraiba type or not. Three Laboratories in the UK confirmed it has coper in it but could not determined the quantity/ratio.( I guess because, they do not have the equipment) The tourmaline were customed faceted with a very highly experienced/respected gem stone cutter in Europe. He literally confirmed to me that the stones were definitely without any doubt from his wide ranges of experience a Paraiba type. To be honest, he is very experienced in the gemstones stones faceting business.

After the faceting, i submitted it to a laboratory in Antwerp, Brussel with specialty in diamond but they claimed to do colour gemstones identification etc. The stones were 9 pieces in total with the highest single of 26 Carats and Smallest of 4carrats.

The laboratory manager came back to me by email that it wasn’t Paraiba type. I then asked them for the for the copy of the spectrograph or any documents relating to how they came into that conclusion. The lab manager refuse to provide the evidence to the method used. I put a bit of pressure on him and he sent me a copy of chemical analysis of a gemstone. But not spectrograph. (UV-Vis-NIR Wavelength absorption spectra graph). Please see the attached analysis.

My problem was that, when i checked for the update on the stones, the laboratory manager said that they weren’t Paraiba types and that he would send the stones back to me by post without me paying for their services.(Then i noticed something seems to be fishing here) I objected to his suggestion by sending an email to him and copying the rest of the team in the lab. He then sent another email to the rest of the staffs that i have agreed to allow someone to pick up the stones on my behalf which was another lie. I sent another email that my gemstones must not be given to anyone except myself and in person. Not by post.

I went and picked my stones from the lab. I then asked him to give me the chemical analysis details of other eight tourmalines and i would pay any amount for it. But he refused to provide it and said, its only for inhouse gemmologist. Not for Customers. He also mentioned that he sent to me were of the same , chemical analysis with the rest of the tourmaline gemstones that i submitted to their lab.

See his last response:
Dear Gideon,

In order for a tourmaline to be called Cuprian Tourmaline stone must have

  • sufficient trace of Copper and Manganese
  • the typical neon/blue color
    Hence based on the predominant color we identified the variety as Verdelite or Indicolite.

I don’t believe in that because the stones came from different locations and not identical in colours.

I also believe from GIA and other labs reports that Paraiba has a bluish/greenish colours. Not only neon blueish colour.

Can someone advise me?

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2

Hi Gideon,

There is a significant amount of Fe (iron) present in the report they provided, and I am not sure what is considered sufficient trace amounts of Cu to be considered Cuprian. Its unfortunate the lab would not identify which analysis they did.

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is the one of the most accurate methods to determine material composition. It is considered destructive and one of the most expensive tests.

Stones undergoing LA-ICP-MS will typically have a distinctive pit or bore hole (5 - 200um in diameter/depth) on one of the girdle or lower girdle facets. I would scrutinize the girdle and surrounding lower girdle facets on the pavilion side, under high magnification. It might not be very obvious, if this process was used, but the best approach is to use oblique illumination to view the surface of each facet in reflected light. The high heat generated by the laser is intense, so the target area is typically near the center, equidistant from facet edges to minimize thermal-shock propagation.

The best thing you can do for this unfortunate situation is take the stones to another lab or to a Geology/Minerology Dept at a University, capable of doing tests like the LA-ICP-MS. This will be the only way you can quantify your concerns or have substantial evidence to validate the results.

You mentioned the stones did not all come from the same locality and, as you hinted at, the stones, theoretically, should vary slightly.

Perhaps the presence of Fe could help provide a clue on locality.

If these stones were mined outside of the Paraiba, Brazil locality, the lab in Brussels, would most-likely be hesitant to label them as such. The majority of the industry has agreed to limit the use of “Paraiba” to that effect.

3

Thanks ever so much Troy for the valuable information. I really appreciate it. I guess the lab could have informed me that they won’t be able to do the identification due to lack of equipment/experience etc. I even mentioned paraiba type coprian tourmaline and it wasn’t from Brazil. A friend said something similar to what you said that the lab may be surprised to see a stone of that size and well custom cut. They may be hesitant to designate that title “paraiba”/Paraïba type.

I have asked some other labs around who claimed to be capable of doing it and that i should send it.
I was very specific with regards to what i want. The paper evidence of the graph and the equipment you mentioned in your message. One came back to now and said they wont be able to do that as they do not have the equipment.

But the question is, these labs takes money from people for services they aren’t capable of doing.

I will check with some universities around and see if that would help. Otherwise, i may have to check with the GIA as they seems to have experienced and equipment to do it.

But i was happy i didn’t agreed to the lab managers dodgy plans. I went there unannounced and pick up the stones.

Once again, thanks so much.

I will update the results as soon as i get another opinion from another lab or universities.

Regards

4

Gideon,

I have to make a correction in my initial assumptions and apologize to the forum here.

I have been doing a “deep dive” into this, because there are some challenging issues and according to several sources, your tourmaline could be called Paraiba, if it meets certain criteria.

Based on a 2006 coordination agreement of the Laboratory Manual Harmonization Committee (LMHC), which was mentioned in the IGS Gem Library article on Paraiba that I posted earlier, it has been accepted to classify certain elbaite tourmaline as Paraiba, regardless of the geographical source locality, as long as it meets what has been agreed upon.

This is definitely against the “common” uninformed stigma that exists and continues to be propagated in the community, to which I have become an example of. I definitely did not thoroughly understand the industry’s stance on what is called Paraiba.

I humbly apologize for that misconception and misinformation.

There is a caveat to this research and a paradigm in my “learning the ropes” of gemology. The report you received from the lab identified a presence of Fe which seems to be above a “trace amount” value. This may not meet the requirement to be called Paraiba, according to the LMHC. There also needs to be a high level of Cu present in order to meet the threshold. The test report you received indicated a trace amount that would potentially result in weak absorption spectral lines, during a polarized spectroscopic test. Unfortunately, this is not encouraging news…however…

Because the previous lab was not forthcoming on which stone was tested and would not provide independent reports for all of the stones you provided, it seems necessary to gain a second opinion and engage another lab with specific tests.

IMHO, I would select two stones (from the different localities) to be the initial test subjects. That way if they do not result as Paraiba, you have minimized your expenses and limited the risk of damage to your investment. Ultimately, you will gain insight to the different localities.

Since you are in the U.K., it seems reasonable to engage the local GIA lab in London or a GRS lab (if present there).

Again, I apologize for my uninformed guidance and hope this response helps the effort to gain information to classify the stones.

Kind Regards,

Troy

5

So…you have 9 pieces ranging in size from 4cts. to 26cts. that you think may be Paraiba. WOW! I have two thoughts: first what do the pieces look like? Do they look Paraiba and second what are your plans for the pieces? Are you planning to set them up on a bookshelf as part of a Collection, put them in jewelry, trade them for a 50 foot yacht, etc.

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The copper content range for a Paraiba is 0.1% to 3% by weight and the manganese from 0.2% to 1.4%.

You’re looking at 1.2164% Mn and 0.0098% Cu