I’m a small scale gemstone dealer in the UK. I buy gemstone and also sell gemstones of high grades. I have got this tourmaline gemstones for a while and i just faceted it to 14 Carrats. I took it to a small laboratory in the uk and they couldn’t identify it as paraiba. They do confirm it has coper in it. I gues because they don’t have either the equipment or knowledge based.
Can anyone help with visual identification or suggest any trusted laboratory in the UK or Europe that can do the identification?
I’m surprised the lab did not do a refractive index to show it was tourmaline. Your stone is heavily included and may in fact be a garnet instead. A simple polariscope test would eliminate garnet as a possibility. Did the lab also test for boron?
Absorption Spectrum
Usually not diagnostic for tourmalines. However, for paraíbas, look for a broad area of general absorption starting at 600 nm. (Present only in gems with high copper content).
With a inexpensive spectroscope (amazon or quicktest.co.uk) this can be checked.
Hi Gideon,
I think Stef is right, you need a better photo. I can’t see any distinct facets on the crown at all. Not saying they are not there, just that I can’t see them. In the photo, I would say the stone looks like it has a waxy luster. So a better photo would help. I’m not sure about the color, either. There are a lot of beautiful colors of tourmaline that are close to paraiba color…for example, “lagoon blue” tourmaline from Namibia.
At one time “paraiba” tourmaline only came from the Brazilian mine at Paraiba, but then similar colors were discovered elsewhere, which were at first called “copper bearing” tourmaline with “pariaba” color to distinguish them from tourmaline with an actual provenance that documented that they came from that mine in Brazil…there’s since been a debate about what to call tourmaline with a lot of copper in it and an intense neon blue color. It isn’t just the presence of copper, but the proportion of copper to iron that helps classify tourmaline as “paraiba”. Here’s a link to a recent article that discusses this: https://www.ssef.ch/wp-content/uploads/2022/07/2022-Krzemnicki-et-al-Paraiba-or-not.pdf
It only took a few clicks to find the article. If you’re going to play with the big boys with stones that are well upwards of $1,000/ct, you will need to be up on your gemology and use the right lab with the right instruments. You need to know what the criteria are in case someone questions your lab, so you can defend yourself. So take notes on the article, the proportion of Cu vs Fe, and the specialized instruments that the lab will need to use to determine that in addition to what the spectrum should look like.
If I were you I would send a lab a very, very good picture of your stone with a color that exactly matches your stone, because a gemologist who has seen a lot of paraiba tourmaline may be able to tell you from the color or the spectroscope pattern the likelihood that your stone will prove out as strongly copper bearing…IDK what the testing is going to cost, but no sense doing it if the color shows evidence that the stone has copper in it, but the dominant absorption bands are iron (Fe+2) bands. Just sayin’ you might save some dollars…good luck with it! -royjohn
Photos can never determine stone ID or chemical content.
Copper absorptions are not at 600nm but are in the 900nm ranges… this is outside of human vision and a hand spectroscope cannot give you copper determinations.
You might want send it along to labs like SSEF, GRS or Gubelin.
If it is truly Cu bearing, you will want to have decent papers on it.
Perhaps your lab there actually did determine it had copper, a regular UV-NIR spectrometer can tell you that. But, to determine country of origin you need to run chemistry using ED-XRF. And it will be a combination of examining the quantitative and qualitative ratios of several elements… (along with a serious amount of data and experience).
Thanks so much for the valuable advise. I really appreciate it.
I know the country and the actual mining site that actually produce the stones. I guess i would only need to do the confirm and certify it if its paraiba or not.
One more question, would it be advisable to confirm the identity of the rough one just like that or shall i get it faceted first and then send all over to the lab as faceted stones for identity confirmation?
Attached are the certificates from the laboratory that i forgot to attached earlier with the stones. Like i said, o asked them about the reading graph that indicate the percentage of copper in it. They couldn’t provide any. But confirmed that its a coper bearing tourmaline.
Gideon, First confirm with a lab that the first one actually is what is hoped… then, I would recommend faceting the second one before incurring lab fees, since you would just have to have it “Re-Certed” again after faceting.
You say you know the country, would you please share that here.
yeah i think if you cant do the basic tests then you should not be representing the trade as a gemologist i know this is an old post i would say its dangerous ground to diagnose from images or based on colour, in my opinion, Apatite has a strong Likeness for Paraiba tourmaline Also Brazilian beryl treated gems also. therefore if your in London the pearl and Gem and Lab in Hatton gardens is a good recommendation,
i know this is a 2023 post but i think it takes more than a certificate to be a gemologist being street smart is just 1 there’s many people who know their way around gem testing it best to learn it yourself before hand
