Fracture Filling in Paraiba Tourmaline: A New(ish) Problem

Fracture Filling in Paraiba Tourmaline: A New(ish) Problem

With Paraiba tourmaline prices through the roof, more and more clients request that the stones are fully certified by an independent lab. As we are busily adding certs to our listings, we started noticing that an increasing number of Paraibas are coming back clarity enhanced. The fillers are not typically identified but currently in use are Opticon, ExCel (both polymer resins) and oils (natural Cedar Wood and synthetic oil such as baby oil). Traditionally, these fillers are used for emeralds, but they are also often detected in other gems, even in expensive sapphires and rubies.

And I am not the only one seeing this trend. In a conversation with staff at AGL I found out that they have seen a fairly noticeable increase in clarity enhancement in Paraiba (as well as in other stones). I was also told by a vendor friend that Richard Hughes from Lotus Gemology has released a note to the same effect; I don’t know where to find this note and I didn’t see it on the website, if you do please let us know so that we can share it.

The problem is not new. Opticon has been applied to emeralds since the 1960s and of course oil fillers have been used on emeralds for centuries. What is new is that there has been (a) a proliferation of fillers and (b) increased use of fillers on gems other than emerald (or red beryl). Even spinel now enjoys this treatment, in addition to another new one that I am mentioning as a side bar: nickel diffusion ( So please be careful about your purchases, especially if they are from countries that do not have the same consumer protection laws in place as the US or the EU or where you do not have any recourse for returns.

The reasons why fillers are used are obvious: supplies are dwindling, demand still on the rise. Most gems that would have been deemed cabochon grade a decade ago are now being faceted and that is not an easy thing to do when they are full of fractures and fissures. Opticon can be applied to help stabilize the material, and even if the hardener is not used to seal the fractures (this is the part that is sometimes referred to as ‘gluing the stone together’), cutting a fracture filled gem is easier. This goes not just for faceting but for cabbing also. I have heard figures quoted at up to 50% use of fillers for lower grade material. How much is really treated is anybody’s guess though, as this part of the trade is not regulated (FTC regulations are mainly about disclosure, we do not have regulations about what can be done to a gem, not here and not anywhere else).

Unfortunately for you and me, it is not really possible to see fillers with the naked eye or even a loupe. On occasion, slightly duller appearance in a cabochon and stronger yet less glowy color can be a tell-tale sign, and I tend to assume that most of the less expensive Paraiba cabs are fracture filled when making a purchase. But for the most part, figuring out if the treatment is present will require a more in depth examination, and sadly, even the brokers who sell the gems do not always know.

This article here by Richard Hughes will show you some photos of how a treated emerald looks under a microscope, and much the same is true for Paraiba since the fillers are the same: Another tell-tale sign is the appearance of rainbow under the microscope, which indicates a fracture even when you cannot see the fracture itself. It’s not easy to interpret inclusions however, and that requires a lot of viewing time (full disclosure: my skills in this department are fairly rudimentary).

Few gem dealers have this much experience with a scope, and even some gemologists and geologists cannot identify fillers. For rough or faceted materials bought on the open market many brokers rely on their own sources to know, and those sources in turn may not be excited about making disclosures they are not required to make in their respective countries, disclosures and that will reduce the value of their transactions. Even for gem dealers, therefore, it is ‘buyer beware.’

In the United States, the FTC (The Federal Trade Commission) requires that all treatments which affect the value of a gem significantly have to be disclosed (such as glass filling in rubies) and while the fine tuning of this claim leaves something to be desired, failure to comply is considered fraud. It also has to be disclosed if the treatment requires special care instructions (such as with glass filled rubies and oiled emeralds). Here’s a detailed article by GIA on what kind of disclosures are required and their history:

The AGTA (of which we are members) actually requires full disclosure of all gemstone enhancements, not leaving the judgment call about value in the hands of gem dealers. It also forbids us to issue our own gemstone certificates or appraisals. They may only come from an independent laboratory.

As you may be aware, not all treatments affect value in all gems. Examples are heat treatment in zircons, aquamarines and most tourmalines. These treatments are permanent, do not affect durability or care, and are in any case difficult to detect. In gems that do not have inclusions, or not enough tell-tale inclusions from which we can draw conclusions, it is actually impossible to tell if they are heated, and this happens even with sapphires and rubies. (This is why a gem lab will say “no gemological evidence of heat” as opposed to “gemological evidence of no heat” – note that the negation, the word “no”, is in a different place and that changes the meaning.)

So how can you, as a buyer of Paraiba, be sure that you know how your gems are treated? The same way I do: by getting a report from a reliable lab. Here’s an article by Hughes on how to select a gem lab for your purposes:

That said, however, you may not be able to expect consistent results, at least not at this stage in research and development, and this can be problematic!

Anecdote: last spring I gave two red beryls to GIA to determine if they were clarity enhanced. In red beryl, the price differential between clarity enhanced gems and those that are not is significant: 30-40% in my estimation. My red beryls came back as clarity enhanced, which was annoying because the seller was certain they weren’t. When I got my results, I requested to see a lab tech for clarification. The tech explained that the majority of red beryls were clarity enhanced. Well yeah but what does a statistical result tell me about THIS beryl? That’s what I wanted to know, I didn’t want to know about most beryls, just this one. I requested a recheck. This means that if they change the results, they pay, if they don’t change the results, you pay ($35 in this case, worth it in my view). The retest was performed – I was told a different tech would be assigned, and the result changed in one case, it didn’t change in the other.

I’ve since had a few of my gems rechecked when they came back as clarity enhanced (mostly I had the emeralds retested), in 9 out of 10 cases the results did not change however.

Last month, I received a GIA report that unexpectedly said ‘clarity enhancement’ on one of my Paraiba cabochons – this gem was from a trusted vendor so I called him with the results. He asked me to please resubmit to AGL because he felt that the report was inaccurate, so I did. It’s expensive by the way, GIA currently charges $65, AGL charges $208, an already discounted rate for AGTA members. I added three more of my Paraibas to the pile and requested a call once they had the results. I even added the GIA report.

After two weeks, I got a call from Chris Smith, the owner of AGL. He told me that none of my four gems submitted were clarity enhanced, and one was also unheated – I didn’t expect that. Chris said he saw the GIA report I included. So why the different results? According to what I wrote down, Chris said that foreign materials trapped during the natural mineralization process are not classified as filler by AGL. A difference in opinion or a difference in interpretation of the visual data? The latter, presumably.

But these differences in interpretation do leave one wondering how fine grained distinctions can really be made with a visual examination. My view? Any gemological results are only as good as the machinery used; only as good as the comparison and research library they have; and only as good as the person’s experience is in interpreting what they see. Also, I would expect less from a report that costs $65, and a more expert answer for $208. And I would expect even more exactness from a $500 report from Gubelin (or $800, depending on the size of the Paraiba). Some labs also get more than one gemologist’s opinion on an image and the more money I spend, the more expertise I want thrown at determining the answer.

It also can’t be ignored that gem labs have different areas of expertise and the expectations they have when they hire staff would correspondingly differ also. Gubelin has an extensive gem library with scans and images they can use for comparison. AGL is known for colored stones, GIA is known for diamonds. Each lab has different equipment for different tests. We cannot assume that a small lab can spend $100,000 on equipment but we also cannot assume that any large lab has every piece of technology that can be bought on the market.

My own experience has been that AGL provides answers most consistent with what my trusted vendors claim in terms of origin and treatment of Paraiba. So that is where I go for the more valuable Paraibas I have. Given the cost, I obviously do not suggest getting a small gem tested. While the value of a gem can be increased if it comes with a report that verifies the stated information on that gem, a $50 gem does not become a $258 gem just because it has a report! I believe AGL will not take any gem under half a carat, and in any case the smaller the gem the more difficult it is to find sufficient inclusions to make a fair assessment. And only appraisal labs will work with mounted gems, so it is best to certify prior to setting or the gem has to come back out.

Obviously I don’t have a magic number for when you should expect a seller’s gem to have a genuine and independent lab report. That is a matter of opinion. As a buyer, I follow these rules: I rarely buy from sources I do not know personally, and to establish a new relationship I may start with a small purchase that I may test. Alternatively I check references. When I buy on location from a smaller broker, I never spend money I cannot afford to lose. I would never (NEVER!) fly to another country to buy a large gem on location in the hopes of saving money unless that particular country has a reliable gem laboratory where I can drop and pick up the gem myself from the lab and buy subject to that certificate. I do not trade with buyers, I do not buy breakouts or used jewelry items with gems, I do not buy from anyone who is not in some sense a vetted seller. Doing business this way costs more money but it exposes me to far less risk. This business can be risky and the only way to minimize it in the end is by knowledge and trust.