New treatment of dark sapphires to make them lighter?

[Blue-Seeker]

Hi, I posted last week about a 3.15 carat blue sapphire with a veil inclusion. Thank you to all of you who helped me out in the thread. I asked the mods to remove that thread because I've been negotiating, so far unsuccessfully, with the store on the stone. So, as of now, I will not be buying that stone, but perhaps we'll come to an agreement and I'll be back with lots of photos.

So I'm back on the search for a blue sapphire in the 2 - 3 carat range. I've been doing some more research on treatments and I am very concerned about something I saw posted on another site, excerpted here because I don't think I can link directly to the site per forum rules. This alert is from July 2011.

"Gemstone Treatment Alert: Ceylon/Sri Lanka Sapphires: Please use the link below for the full story and any updates I may list as I find out more information. But a quick summation is that Sri Lanka buyers have been buying up lots of the dark dark blue sapphire rough from Nigeria and Australia and have some how discovered a way to use Beryllium Treatment to lighten these overly dark and less valuable sapphires into close to top colors and far more valuable blues! The issue is many are just being sold into the Market as Ceylon/Sri Lanka origin materials and the only treatment(s) disclosed are “Heat” or “Heat Only” or “Heated”, no disclosure of Beryllium Diffusion/Treatment disclosed!"

The link referred to on the webpage just goes to another summary of the same information with no follow-up.

Has anyone else heard of this? This makes me suspicious of buying any recently cut sapphires labeled Ceylon/Sri Lanka origin. How good are the labs at picking up these treatments? And how reliable are the labs?

Another question, if a sapphire is recut, will that expose beryllium treatment because the beryllium doesn't penetrate the entire stone, just the surface of the stone?

 

[Roger Dery]

Hi Blue-Seeker,
You inserted:

This alert is from July 2011.
"Gemstone Treatment Alert: Ceylon/Sri Lanka Sapphires: Please use the link below for the full story and any updates I may list as I find out more information. But a quick summation is that Sri Lanka buyers have been buying up lots of the dark dark blue sapphire rough from Nigeria and Australia and have some how discovered a way to use Beryllium Treatment to lighten these overly dark and less valuable sapphires into close to top colors and far more valuable blues! The issue is many are just being sold into the Market as Ceylon/Sri Lanka origin materials and the only treatment(s) disclosed are “Heat” or “Heat Only” or “Heated”, no disclosure of Beryllium Diffusion/Treatment disclosed!"

Someone may have posted this info on a particular site, but the Beryllium treatment of corundum goes back roughly 10 years. As has been noted, it was originally used to propagate the amount of Padparadscha colored Sapphires. But it was found to assist with other colors of corundum as well.

Has anyone else heard of this? This makes me suspicious of buying any recently cut sapphires labeled Ceylon/Sri Lanka origin. How good are the labs at picking up these treatments? And how reliable are the labs?

This has been the topic of numerous articles in trade publications since it was first discovered by several prominent laboratories. It has also been covered by Gems and Gemology - though I don't currently have access to specific issues for your review. Perhaps someone else may have quick access to them.

Another question, if a sapphire is recut, will that expose beryllium treatment because the beryllium doesn't penetrate the entire stone, just the surface of the stone?

Early on with the Beryllium process, the penetration was not complete in the corundum. And for those, yes, it was possible to recut one of them and reduce, or remove completely the added color. However, with the more recent techniques, it has been shown that the penetration is to the core of the stone. And then of course, recutting has little effect.

 

[minousbijoux]

This is why most of us on this forum won't buy corundum without a reputable lab report. I think Pandora has better knowledge of which international labs have the equipment to test for diffusion and other treatments, but domestically, I would not buy sapphire (unless it was really inexpensive) without a report from either GIA or preferably AGL.

 

[Arkteia]

I thought Be treatment was used to make light unsaturated sapphires darker and prettier, not vise versa.
(Luckily, we have people who bring knowledge to the PS and can ask them).

 

[Pandora II]

It has been know about for sometime - at least since 2009.

It requires high heat to do this so that is always a good thing to rules out. There are also some interesting inclusions that are indicators of Be treatment in blue sapphires (absence of these doesn't rule it out, but presence rules it in if that makes sense).

You need to run LA-ICP-MS to be sure, but this does have some problems. One possible issue is that some Madagascan blue sapphires contain Be naturally, although generally in lower concentrations that those that have been treated. There is also the possibility that a stone has been heated in a furnace that was previously used to do Be treatment and is thus unintentionally treated.

My understanding is that the treatment does not turn a sow's ear into a silk purse and it is generally used for commercial grade stones. Stick to low-heated or unheated stones and you shouldn't have any problems.

The stones are often Sri Lankan in origin but treated in Thailand (it's officially illegal to carry out Be treatment on stones in Sri Lanka and the Sri Lankan gem dealers are very keen for it not to become a practice as it buggers up the market for everyone if people don't have faith in the stones).

I can link to some in-depth articles if anyone is interested in wading through the tables of element peaks etc.

 

[Blue-Seeker]

Thank you for your responses, Roger, minousbijoux, crasru, and Pandora.

Yes, Pandora and Roger, any information you can link me to would be appreciated.

Pandora, yes, I know there are some inclusions that definitely rule in high-heat treatment. I did find some photos on the web showing natural versus high-heat inclusions that were really helpful in my evaluation of the 3.15 carat stone I've been looking at in a local store.
I clearly saw zoning lines -- I'm not sure if that's the correct term. And the veil or feather was really interesting under the scope. I did not see any silk in the stone. However, I did not see any melty-looking bubble-type inclusions in and around the veil either. The stone is a consignment stone and it may have been purchased longer than 10 years ago. I will ask the store owner about it. But is an older stone, for example a stone purchased in the 1990s, less likely to have treatments beyond low heat?

minousbijoux, this forum has convinced me to be skeptical of any sapphire that doesn't come with a lab report. The sapphire market is truly a minefield. I think it is going to take me a while to find a stone.

Roger, are cutters like yourself able to determine what treatments a given sapphire has undergone? I'm asking because it sounds like a lot of the equipment needed to identify the treatments is pretty specialized. In other words, not something most non-labs would own.

 

[Blue-Seeker]

I thought Be treatment was used to make light unsaturated sapphires darker and prettier, not vise versa.
(Luckily, we have people who bring knowledge to the PS and can ask them).

This is what I thought, too, which is why this "Alert" concerned me. Especially in light of what Roger said that the newer treatments penetrate to the core of the stone.

 

[Pandora II]

http://www.google.co.uk/search?sourceid=navclient&hl=en-GB&ie=UTF-8&rlz=1T4GGLL_en-GBGB364GB364&q=beryllium+blue+sapphires

Best one to read.

http://www.aigsthailand.com/FieldTripsDetail.aspx?tID=32&lang=EN

By the incredible Vincent Pardieu

 

[Roger Dery]

Blue-Seeker,
I apologize if my response isn't as complete or seems short. I have only been back in the US for less than a day and am still a little jet lagged. And, may not be thinking too clearly

You noted:

I clearly saw zoning lines -- I'm not sure if that's the correct term.

This is not necessarily a bad thing, in Sapphire.

But is an older stone, for example a stone purchased in the 1990s, less likely to have treatments beyond low heat?

It would have been most likely subjected to a higher heat, say in the 1600*C to 1950*C range. Starting at roughly 1600*C is where the naturally occurring rutile inclusions begin to melt and "diffuse" into the balance of the crystal structure (usually improving its color). At 1950*C or thereabouts it is possible to "induce" diffusion by placing additional titanium oxide in the flux prior to heating. This way, one can "assist" with improving the color. That is, assuming the hue and saturation were not acceptable to begin with (as in, too light).

Much of this work taking place in Thailand is, and has been, performed in primitive conditions. It is only in recent years that modern ovens have been employed.

Roger, are cutters like yourself able to determine what treatments a given sapphire has undergone? I'm asking because it sounds like a lot of the equipment needed to identify the treatments is pretty specialized. In other words, not something most non-labs would own.

As a general rule, no, we are not able to make that determination. That being said, this is my 31st year in the colored stone trade, and some things I have seen during my tenure allow me a slightly wider range of insight into what one can expect. But truly, one can not know it all and the machinery and equipment required to make the right call is very expensive -- into the hundreds of thousands of dollars for some.

I hope you find this helpful.

 

[Blue-Seeker]

Thank you, Pandora and Roger, for the links and additional information on heat treatment. The more I learn about sapphires, the more cautious I become about what to buy. The best thing about spending so much time gazing at the 3.15 carat consignment stone is that I have a much better understanding of what my hue, tone, and saturation preferences are. I also have a much better understanding of what to expect in terms of inclusions and how the inclusions may change as a result of high heat treatment.

If I'm reading Roger's last post correctly, it sounds like most stones, if heated, are heated at extremely high temperatures, and this then increases the chances that they have been exposed to other treatments. Now I'm wondering if I should stick to unheated stones only? Because when a vendor states under treatment "H" or "Heat Only," I've been assuming that meant "low" heat. Apparently, that's not the case, or am I confusing two different things here?

 

[Roger Dery]

Blue-Seeker,
You noted....

If I'm reading Roger's last post correctly, it sounds like most stones, if heated, are heated at extremely high temperatures, and this then increases the chances that they have been exposed to other treatments. Now I'm wondering if I should stick to unheated stones only? Because when a vendor states under treatment "H" or "Heat Only," I've been assuming that meant "low" heat. Apparently, that's not the case, or am I confusing two different things here?

I took a little time to review my notes from the World of Gems Conference last fall. Chris Smith of AGL was one of the speakers. In an earlier post I noted 1600*C as the low end of temperatures that may affect the color of Sapphires due to the Rutile inclusions melting into the structure of the stone (diffusion).

It appears that the 1600*C figure was incorrect due to Chris' recent research. In his paper, he discusses the fact that Rutile will begin to break down at roughly 1400*C - and that it is a gradual process as compared to an exact, precise temperature.

As has been noted in the literature, low temperature heating (say below 1400*C) is more difficult to detect as the changes may not be noticeable using standard techniques. One also must remember that both Sapphire and Ruby were created under pressure, and temperatures in the 1950* to 2000* range while in the earth. Therefore, there may be remnants of its origin that may appear non-naturally occurring.

 

[Blue-Seeker]

Blue-Seeker,
You noted....

If I'm reading Roger's last post correctly, it sounds like most stones, if heated, are heated at extremely high temperatures, and this then increases the chances that they have been exposed to other treatments. Now I'm wondering if I should stick to unheated stones only? Because when a vendor states under treatment "H" or "Heat Only," I've been assuming that meant "low" heat. Apparently, that's not the case, or am I confusing two different things here?

I took a little time to review my notes from the World of Gems Conference last fall. Chris Smith of AGL was one of the speakers. In an earlier post I noted 1600*C as the low end of temperatures that may affect the color of Sapphires due to the Rutile inclusions melting into the structure of the stone (diffusion).

It appears that the 1600*C figure was incorrect due to Chris' recent research. In his paper, he discusses the fact that Rutile will begin to break down at roughly 1400*C - and that it is a gradual process as compared to an exact, precise temperature.

As has been noted in the literature, low temperature heating (say below 1400*C) is more difficult to detect as the changes may not be noticeable using standard techniques. One also must remember that both Sapphire and Ruby were created under pressure, and temperatures in the 1950* to 2000* range while in the earth. Therefore, there may be remnants of its origin that may appear non-naturally occurring.

Thanks for the additional information, Roger. The part of your post I underlined is something I've read on other sites, including, if I remember right, the Ruby-Sapphire excepts from the Hughes book that are available on line.

Here's a thread from last year that has some additional information on sapphire treatments. https://www.pricescope.com/community/threads/be-treatment-in-sapphires-any-experts-lurking.147095/

This thread makes mention of the high cost of the equipment needed to detect treatment. So I continue to have concerns about reports that say "heat only," because how do you know that the lab making that claim has the proper equipment to detect all the treatments, given how expensive they are? Can I trust the lab reports? Again, I'm learning, so if I a way off base here, please let me know.

I keep coming back to what Pandora was saying about particular inclusions in her first post on this thread, that "the absence of these doesn't rule it out, but presence rules it in." The photos of inclusions I saw online included some fairly distinct "melted" looking blobs inside heavily treated stones. I think I may take a trip to the mall with my loupe and look at sapphires that are likely to be heat treated and compare what I see in those stones to the photos of inclusions I've seen online.

The thread I linked makes reference to chrysoberyl being heated as well! I thought that chrysoberyl, tsavorites, and spinels were typically not heated? This is making my head spin a bit.

 

[Michael_E]

It has been know about for sometime - at least since 2009.
.
.
.
My understanding is that the treatment does not turn a sow's ear into a silk purse and it is generally used for commercial grade stones. Stick to low-heated or unheated stones and you shouldn't have any problems.

This article from the GIA, published in 2003 has a great image of an experiment that they did which had the capacity to turn a sows ear into a silk purse.http://lgdl.gia.edu/pdfs/su03a1.pdf See the image on the top of page 112, of the dramatic lightening of a very dark blue sapphire slice. I think that it's kind of neat that many sapphires can be lightened like this. Many of the sapphire deposits in the world are composed of dark, nearly black sapphire crystals that can be turned into very nice blues with this technique and still maintain all of the other features of their natural origin. As long as you know what you're getting, what's not to like?

 

[Blue-Seeker]

It has been know about for sometime - at least since 2009.
.
.
.
My understanding is that the treatment does not turn a sow's ear into a silk purse and it is generally used for commercial grade stones. Stick to low-heated or unheated stones and you shouldn't have any problems.

This article from the GIA, published in 2003 has a great image of an experiment that they did which had the capacity to turn a sows ear into a silk purse.http://lgdl.gia.edu/pdfs/su03a1.pdf See the image on the top of page 112, of the dramatic lightening of a very dark blue sapphire slice. I think that it's kind of neat that many sapphires can be lightened like this. Many of the sapphire deposits in the world are composed of dark, nearly black sapphire crystals that can be turned into very nice blues with this technique and still maintain all of the other features of their natural origin. As long as you know what you're getting, what's not to like?

Good point. I guess my concern is less with the treating and more with the disclosure of the treatment. If the treatment is disclosed and the stone is priced accordingly, that makes all the difference.

 

[Roger Dery]

Blue-Seeker,

The thread I linked makes reference to chrysoberyl being heated as well! I thought that chrysoberyl, tsavorites, and spinels were typically not heated? This is making my head spin a bit.

If you were to see yellow Chrysoberyl in the rough, it would be possible to mistake it for yellow Sapphire rough. And since they are sometimes mined in the same pits or trenches, it may be possible the Chrysoberyls were thrown into the furnace in error, or maybe deliberately to see what it would do.

During the heating process, Chrysoberyl gives up Beryllium. And, if corundum is also in the same crucible, and near the 1950*C range, it is possible that molecules move, affecting the outcome of the corundum. Effectively, allowing molecules to 'diffuse' into the corundum's lattice. Thereby changing the color of the corundum.

There have been reports in the trade that some dealers and treaters are trying their tricks on Tsavorite and Spinel. However, there has been precious little info coming out of the labs or in trade literature regarding this potentially problematic scenario.

There are numerous gem cutters that are noted as being valuable to work with - and you can see many of their names here:
[URL='https://www.pricescope.com/community/threads/sites-selling-colored-gemstones-and-jewelry.94723/']https://www.pricescope.com/community/threads/sites-selling-colored-gemstones-and-jewelry.94723/[/URL]
They can provide gems cut by their own hand and would normally be able to validate the stones' origin as well as other useful criteria.

Blue-Seeker, probably more than you wanted to know, but hopefully this is useful to you and others.

 

[chrono]

Heating of blue corundum to lighten the colour to make them saleable has been going on for years, regardless of origin. The addition of added minerals under high temperatures (almost the melting point of corundum) has been done for many years as well. This process is continuing to be improved where initially, the colour was only on the outer rim, today the “dye” permeates evenly throughout the stone so that when it is recut, you cannot tell the difference. Diffusion uses not just beryllium but other minerals like titanium.

Sometimes, with knowledge and a trained eye, it is possible for reputable labs and appraisers to determine that the sapphire is only heated and not diffused. Sometimes, this cannot be determined (via certain tell tale signs) and this is when the lab will advise the customer to send the stone for further testing. This is why I only trust certain labs, mainly AGL and GIA to make the determination as to whether the stone has been heated and/or diffused. I believe that GIA has the LA-ICP-MS machine to test for beryllium. Do note that sometimes a sapphire might contain traces of beryllium naturally under the earth. H or Heat only WILL include stones that have been diffused – not all heated sapphires are diffused but all diffused sapphires are heated. Labs and vendors do not differentiate between “low” and “high” heat.

In the every changing world of treatment, treaters will always find ways to improve any junk material whenever and wherever possible. Cat’s eye chrysoberyl have been irradiated but so far, faceted chrysoberyl is untreated. Chrysoberyl, however, have been used for the beryllium diffusion process for sapphires. Tsavorite seems untouched at the moment. I’ve read about spinels being heated in an attempt to improve colour (not successful) and clarity (some success). Garnets (tsavorite is a garnet) have been clarity enhanced by resin filling but so far is undisclosed.

It is not possible to make the detection of diffusion and heating armed only with a loupe. If you do a search on PS with the keywords diffusion, LA-ICP-MS and the like, you will find oodles of information like the one below:
[URL='https://www.pricescope.com/community/threads/slp-gem-lab.143681/page-2']https://www.pricescope.com/community/threads/slp-gem-lab.143681/page-2[/URL]

 

[Blue-Seeker]

Thank you, Roger and Chrono, for the detailed information. And thanks for the link, Chrono. I have been reading as much as I can find on this topic, even though much of the chemistry is over my head! But the photos in the articles and links have been very helpful. Also the references on which labs to work with. I see many stones listed as certified unheated, but the certifications are from labs other than AGL or GIA. Would I be correct to assume, Chrono, and the others on this forum who buy only certified sapphires, that if you bought a stone certified as unheated from a lab other than GIA or AGL, that you'd pay for a new cert by AGL or GIA? I am willing to incur this cost. I think it's definitely worth the add-on to the stone's cost.

ETA: Thanks also for the information on treatment of gems other than sapphires. It is good to know there are still a few gems that remain untouched. Though that could change at anytime, I suppose, with the development of new technologies or lucky accidents in the burners.

 

[chrono]

Correct; if shopping for a sapphire (just plainly heated or untreated), I'll go with AGL's relatively inexpensive fast track brief to verify the treatment, or lack of it. I believe the pricing to be around $55 or so.

 

[Blue-Seeker]

Correct; if shopping for a sapphire (just plainly heated or untreated), I'll go with AGL's relatively inexpensive fast track brief to verify the treatment, or lack of it. I believe the pricing to be around $55 or so.

Thanks, this is good to know. Not too expensive either for peace of mind or if I ever want to sell it or trade it in.

 

[Pandora II]

Please don't try and ID inclusions with a loupe. It takes a lot of experience to be able to do that. A gemmologist I take my unheated stones to is expert on inclusions (he uses a top of the range gemmological microscope to look at them not a loupe) and I trust him 100% to tell me if I need to get more information or not.

There are definite signs that corundum has been heated above a certain temperature - intact rutile needles for example only start to dissolve at around 1400, whereas treatment to improve colour may well take place around 700 degrees.

Michael, I can find the photo of the dark blue sapphire to lighter blue sapphire that you are referring to? (My comment applied only to this by the way - general Be treatment has spectacular results.)

 

[Blue-Seeker]

Please don't try and ID inclusions with a loupe. It takes a lot of experience to be able to do that. A gemmologist I take my unheated stones to is expert on inclusions (he uses a top of the range gemmological microscope to look at them not a loupe) and I trust him 100% to tell me if I need to get more information or not.

There are definite signs that corundum has been heated above a certain temperature - intact rutile needles for example only start to dissolve at around 1400, whereas treatment to improve colour may well take place around 700 degrees.

Michael, I can find the photo of the dark blue sapphire to lighter blue sapphire that you are referring to? (My comment applied only to this by the way - general Be treatment has spectacular results.)

Thank you for the caution, Pandora. It's hard not to get ahead of myself here.

I have to say, after the little bit of reading and research I've done, I'm shocked at the sheer number and types of treatments for sapphires. I've often seen the phrase "assume any sapphire is treated." But at some point the treatments seem so extensive that the difference between the original rough and the final product in terms of appearance is so great that I have to ask, is it still a "natural" sapphire? Of course it's natural in that it came out the ground rather than created in a lab. It was mined. But beyond that, in terms of color, if it comes out of the ground as gray-white and is "transformed" by modern chemistry into a stunning blue, that seems a little unnatural to me. In one of my first threads, I stated that I was okay with heat treatment. But that was when I was under the assumption that heat was a simple, straightforward, traditional process. Now I see that "heat only" can mean any number of types of heat, some more "transformative," ahem, than others.

I'm having some cognitive dissonance about this, I admit.