Sapphires from Thailand
(updated 18 September 2003)
late in 2001, treated sapphires from Thailand have created
a great deal of controversy (see ‘The
Skin Game’ and ‘Understanding
the New Treated Pink-Orange Sapphires’ for full
As of the current writing, the evidence is overwhelming
that such stones owe their color to a form of outside-in diffusion
of coloring agents.
In the summer of 2003, the GIA published
a major new study on beryllium diffusion of ruby and sapphire.
This is currently the most complete study to date on these
stones, and is a landmark paper for the cause of color in
corundum and gems in general.
diffusion of ruby and sapphire by John L. Emmett, Kenneth Scarratt,
Shane F. McClure, Thomas Moses, Troy R. Douthit, Richard Hughes,
Steven Novak, James E. Shigley, Wuyi Wang, Owen Bordelon and Robert
E. Kane, Gems & Gemology, Summer 2003, pp. 84–135.
The above paper confirms what has been strongly suspected
since late January of 2002, namely that the outside-in diffusion of
light elements (primarily beryllium) produces the color changes seen
in these treated stones.
This process is basically the same as that used with
surface diffusion treated blue sapphires in the past, but with different
chemicals. Both the AGTA and GIA labs are now labeling this treatment
process “lattice diffusion” (previously termed ‘bulk’ diffusion)
and that information will be clearly listed on their identification
Over the past years, a number of questions have arisen
regarding this treatment. The following are answers to many of these
What is the color range of
goods produced by this process?
This treatment involves outside-in diffusion of light-element
coloring agents to create trapped-hole color centers. These color centers
produce a yellow color. Applying this treatment to a near-colorless
or green stone turns it yellow. The same treatment applied to a pink
stone turns it orange, while a purplish red stone (ruby) becomes a
has also been demonstrated that the process may
produce a lightening
of the color of dark blue sapphires. Such stones
have blue cores with colorless rims and are being
encountered more and more frequently. Elements beyond
beryllium may be involved and intensive investigations
are currently underway at major gem labs.
It was reported in early
2002 that such stones owe their color to a change in the valence
state of iron already in the stone. Is this true?
Reports to this effect were issued by a couple labs.
It is now generally understood that these reports were flawed.
of before and after spectra suggest that Fe is not
playing a major part in the coloration of these
stones. This fact has been confirmed in laboratory
experiments by John
Emmett and Swarovski,
both of which independently found that diffusion
of beryllium produced colors identical to what we
have seen in these gems.
It has been reported that “internal
migration” of elements already in the gem is responsible for
the color changes. Is this true?
This theory was proposed by one gemologist (Bangkok
Post, 2 July, 2002 and 18 Sept. 2002). To the best
of our knowledge, no gemological laboratory outside of Thailand
has adopted this nomenclature.
the elements originally in the gem no doubt affect
the success of the treatment, even dealers and gemologists
in Thailand now admit that the color of these stones
results from outside-in (‘lattice’) diffusion
of beryllium. In other words, the external
migration of beryllium into the gem is
the key to this treatment, rather than the internal
movement of atoms already there. Beryllium is an
element not normally found in corundum in the amounts
detected in these treated stones.
latest study of John Emmett and Troy Douthit (5 Sept.
2002) involved diffusion of beryllium into high-purity
synthetic colorless sapphire. The result was a brown to orange
color, with absorption features identical to those found in
the treated stones from Thailand. What this shows is that
diffused beryllium is mainly responsible for these color changes,
rather than any internal migration, as suggested by Perreti.
These experiments also discredit the “catalyst”
theory recently proposed by another gemologist. To put it succinctly, beryllium has been proven
to be the main colorant, not a modifier, not a catalyst.
Thai burners claim they add
nothing to these stones during the cooking. Is this true?
Statements in this regard are quite contradictory. In one breath
Thai burners have been quoted as saying that they add nothing, but
in the next some admit to adding fluxes and even chrysoberyl (Colored
Stone, July/Aug. 2002). It is our belief that both fluxes
and chrysoberyl would qualify as “additives.” The chemical
formula of chrysoberyl is BeAl2O4. Be is the
chemical symbol for beryllium. Chemical analyses of these treated stones
have now proven beyond doubt that beryllium is being added to these
stones from outside.
Thai burners/dealers point
to the fact that stones react differently even when burned together
as proof that nothing is added. Is this true?
In our opinion, no. The current theories on cause of color
in these gems suggest the light element (usually beryllium) added during
the treatment reacts with elements already in the gem to produce the
final color. Different combinations of internal chemistry will thus
react differently. But the light element added is key to success. Without
the outside-in “lattice” diffusion of this light element,
this treatment would not produce the results it does.
It has been suggested that,
since the added color of some of these stones penetrates the gems
entirely, they do not meet the traditional definition of “surface
(‘lattice’ or ‘bulk’) diffusion.” Is
Again, in our opinion, no. The traditional meaning of surface
diffusion had more to do with the fact that colorants are being introduced
through the surface of a gem, rather than simply that the color layer
is restricted to the surface regions. The important difference between
lattice diffusion (surface diffusion) and other forms of heat treatment
is not that the color lies at the surface, but that coloring agents
are artificially introduced into the gem from outside. This outside-in
diffusion of coloring agents is the key distinguishing characteristic
of the lattice-diffusion process.
It has been suggested that,
since “traditional” corundum heat treatment involves
diffusion, that these stones should be considered the same. Is this
Again, in our opinion, no. “Traditional” in terms
of corundum heat treatment was previously defined and agreed to by
the world's gemological labs and trade associations as “heat
only.” These agreements included Thai gem trade associations
and labs. Scientifically speaking, such “heat only” actually
involved diffusion of hydrogen. This is not a new discovery, and has
been understood for well over a decade. But when these stones first
entered the market in the late-1970’s, this was not understood,
and so dealers were sold these goods unknowingly. Thus a special exemption
was made for them.
parties in Thailand now ask that a special exemption
also be made for their beryllium-diffused goods.
But if special nomenclature exemptions are possible
every time a new treatment appears, the current
system, which has taken years of tedious meetings
to put together, will quickly become a useless swamp
of special interests. The world gem trade/gemological
community has been hostile to the idea of a beryllium
exemption, in large part because the warnings went
out so quickly that most dealers abroad did not
get stuck with the goods. Thus they
were free to make an unbiased judgment because they
did not have a stake in the outcome. In other words,
they were free to choose between doing the right
thing and the selfish thing.
January 2001, beryllium diffused goods have mostly
been “buyer beware,” an idea that is
well understood in Thailand. The fact that some dealers
in Thailand have continued to trade these goods,
knowing the potential risks, is their business. But
ignorance is no longer a valid defense.
It has been suggested that
there are vast differences between the blue (titanium-based) lattice
diffusion of the past and the new yellow (beryllium-based) lattice
diffusion of today. Is this true?
Not really. Both treatments involve diffusion of a foreign
element into the gem to produce changes in color. Whether or not a
gem is considered lattice diffusion treated has nothing to do with
the type of element being diffused into a material, nor the efficiency
of the process.
How can gems treated by this
process be identified?
In many cases, gems treated by this process can be identified
by immersion in 3.32 liquid, which reveals a yellow-orange layer at
and just beneath the surface of the gem. But in other cases, the color
may penetrate entirely through the gem. Gemologists around the world
are currently working to develop detection methods for all stones treated
by this process.
gem does not come from the “trillion”
mine, but is a Madagascar pink sapphire with an
orange color rim created by beryllium lattice diffusion.
The gem is immersed in di-iodomethane. Note
that recutting such stones will produce a loss of
the orange color. Photo: R.W.
Some treaters/dealers claim
that these treatments are stable and merely finish the job that nature
started. Is this true?
While color stability is an important issue, it is not the
only issue. Synthetic corundums all have completely stable color, but
no one would suggest that they could be sold as natural on that basis.
Similarly, the basic ingredients of sapphire (aluminum and oxygen)
all have the potential to become sapphire. There is no question that
humans have the ability to improve upon nature. That is not an issue.
any gem can today be produced in a laboratory in
bigger and better qualities than that found in nature.
Buyers today willingly pay more for natural stones
because they value the rarity and “naturalness” of
natural stones. If this were not the case, then treaters
should have no fear about full disclosure of treatments.
The fact that treaters are often shy to fully disclose
such treatments is clear evidence that such disclosures
are important in the decision-making process of consumers.
It has been suggested that
because some of these stones are unidentifiable except by advanced
techniques, that they should be allowed to be sold as "enhanced,” rather
than “treated.” Is this true?
The fact that something is difficult to identify has nothing
to do with how it is categorized. We expect identification techniques
to improve as gemologists become more familiar with the material. But
even if identification remains difficult, it would not change the disclosure
It has been suggested in
the Thai press that foreign dealers’ objections to these
stones are merely an attempt to steal Thai trade secrets. Is this
This has nothing to do with trade secrets. In much of the world,
it is considered fraud to sell a product without fully disclosing any
information that might affect the value of the product. For example,
in Thailand and elsewhere, it is considered fraud to sell a Rolex watch
that is not made by Rolex. It doesn't matter that in the copy the parts
are all the same, or even that the copy keeps time just as well as
the Rolex. When a buyer buys a Rolex, they expect it to be a genuine
Rolex and not a copy.
buyers are not asking to know the exact recipes for
such treatments, but only the general methods. If
chemicals are being inserted (‘lattice diffused’)
into a gem to produce color changes that mimic nature,
buyers must be informed of this. If sellers wish
to sell into most foreign markets, they will have
to disclose this to buyers. If they do not wish to
disclose such information, they must realize that
many buyers will simply stop doing business with
It has been suggested in
anonymous e-mails and press articles from Thailand that the AGTA
has attempted to extort $500,000 from the Thai gem trade as a result
of this treatment. Is this true?
No, it is not. AGTA president Richard Greenwood has called that statement: “…a
says that the $500,000 in question was actually an
AGTA fundraising effort to pay for research into
these gems. A letter requesting funds for the research
on lattice diffusion-treated sapphires was sent to
all AGTA members in the spring of 2002, he said.
In addition, AGTA vice president Jeffrey Bilgore
met with members of the Thai Gem and Jewelry Trade
Association, presenting them with the letter written
in English and Thai along with an outline of a three-step
plan for assistance.
[the fundraising letter] was not directed at the
Thai gem and jewelry community. It went to the entire
AGTA membership. There has never been correspondence
that strong-armed anybody,” Greenwood says. “We
created a research fund. It would be helpful if the
Thai Gem and Jewelry Trade Association helped with
between board members of the AGTA and members of
Thailand’s trade were held and it was suggested
that, since this problem was one of Thailand’s
making, that foreign labs and trade associations
should not have to bear the cost of research alone.
While it is difficult to put an exact dollar figure
on that cost, there is no question that it is substantial,
and as of this writing probably reaches into the
hundreds of thousands of dollars when one factors
in lost time, outside chemical analysis fees, travel
costs, sample stone purchases, etc.
there is a history of improper treatment disclosure
from Thailand. During the late 1970’s, large
quantities of heated sapphires were sold by Thai
treaters without any disclosure that they had been
high-temperature heat treated. In the 1980’s,
rubies from Thailand were sold as simply heated,
but it was later proven that they contained glass-filled
surface cavities. Again, in the 1990’s, rubies
from Thai ovens were sold as simply heated, and we
now know that they have had their fractures artificially
healed with fluxes. Unmasking all of the above takes
time and money. It is unfair to expect the rest of
the world to have to spend money time and time again
to deal with problems created by improper disclosure
by some treaters and traders in Thailand.
Did some labs originally
issue “heat only” certificates on these stones?
It is possible and not even surprising that stones might be
initially misidentified. As with any undertaking, mistakes are possible
and there is a learning process. Since the labs are not treating the
gems themselves, and since most gemologists do not have paranormal
abilities, they cannot know everything immediately. Scientific work
is based on careful weighing of evidence and open publication of the
findings. If others have problems with the determinations, they are
welcome to voice these opinions. But such opinions should stick to
the evidence and also be openly published.
It has been reported that
some stones contain recrystallized (synthetic) corundum on their
surfaces. Is this true?
Yes, it is. Kenneth Scarratt of the AGTA lab has published
report on this question, and the GIA has added a further
report. Such synthetic regrowths have been found most often in
yellow stones treated by this lattice diffusion process. We should
add that such melting and redeposition is also found in treated rubies
from Möng Hsu, Burma. For more on this topic, see ‘Foreign
Affairs’ by Richard Hughes.
It has been reported that
the GIA's data is wrong. Is this true?
the GIA's original report, an aluminum (Al) column was
mistakenly included in one table, but that mistake in no way
invalidated the other data obtained. Our current understanding
is that all the data suggests that the yellow color of these
stones is a result of outside-in diffusion of coloring agents
(particularly beryllium). The latest data from the GIA (Summer
2003) can be downloaded
at this link. Due to a lack of calibration standards,
the initial numbers were slightly off. The fundamental supposition
put forward by the AGTA and GIA labs has remained unchanged
– namely that these stones were treated by a lattice-diffusion
process involving outside-in diffusion of light elements.
This fundamental information has been correct since January
2002, when the first SIMS analyses revealed elevated beryllium
levels in the skins of treated stones. At the end of January
2002, these findings were presented to a major meeting of
gemologists and traders from around the world, including many
It has been suggested that
certain groups in the US are prejudiced against treated gems and
that the AGTA/GIA labs are working on their behalf. Is this true?
The AGTA and GIA labs do not take any stand on such a question.
Their mission is simply to provide accurate information regarding the
presence or absence of any treatments on a given stone. In cases where
a gem is found to be treated, they try to describe the type of treatment
to the best of their abilities. It is up to the buyer/marketplace to
determine what is or is not acceptable.
to the AGTA
enhancement guidelines, which AGTA members must
follow and which have been in place for many years,
all enhancements must be disclosed to the buyer at
the time of sale. It is not enough to simply say
a stone has been heated when something more has been done.
The evidence in the case of these stones is clearly
that something beyond ordinary heat treatment has
Some have suggested that
terms like “lattice” or “bulk” diffusion
are too technical to use with consumers. What would be a simple way
to describe these stones?
Jewelers can simply tell their customers that these stones
are artificially colored with beryllium. Such language is short, sweet
and – most importantly – honest.
Below we list in chronological order the major online references that
discuss this treatment.
on treated orange sapphires by Palagems.com, Nov. 16, 2001–Jan.
sapphire alert by the AGTA GTC, posted 8 Jan., 2002
information on heat-enhanced orange-pink (padparadscha-like) sapphires
from Madagascar by the Gem and Jewelry Institute of Thailand,
posted Jan. 17, 2002
new corundum treatment from Thailand by the GIA, posted
28 Jan., 2002
Gems & Gemology: GIA researchers uncover important
data on new treated corundum by the GIA, posted 15 Feb.,
skin game by Richard W. Hughes, posted 19 Feb.,
sapphire treatment still a mystery by Marlene A. Prost, Colored
Stone, Jan./Feb. 2002
see red over sapphires by Somporn Thapanachai, Bangkok
Post, 3 April, 2002
Gems & Gemology: An update on the orange to
orangy pink treated natural sapphires by the GIA, posted
19 April, 2002
characterization of sapphires recently treated in Bangkok by
the AGTA GTC, posted 19 April, 2002
Gems & Gemology: Swarovski scientists identify
possible source of beryllium in new treated sapphires by the GIA, posted 3 May, 2002
the new treated pink-orange sapphires by John Emmett
and Troy Douthit, posted 13 May, 2002
system to classify gems gets US backing by Somporn Thapanachai, Bangkok
Post, 14 May, 2002
gem players meet about treatment by Mick Elmore, Colored
Stone, May/June 2002
denies caving in over sapphire treatment by Somporn Thapanachai, Bangkok
Post, 6 June, 2002
in stones from trace elements’ by Somporn Thapanachai, Bangkok
Post, 2 July, 2002
enhancement of natural fancy sapphires with a new heat-treatment
technique by A. Peretti and D. Günther, posted 18 July,
and ICA join forces to announce bulk diffusion process on corundum by
the AGTA, posted 26 July, 2002
to defend stone treatment by Somporn Thapanachai, Bangkok
Post, 21 Aug., 2002
offered in dispute on stone treatment by Somporn Thapanachai, Bangkok
Post, 2 Sept., 2002
diffusion coloration of sapphire: A summary of ongoing experiments by John L. Emmett and Troy R. Douthit, posted 5 Sept.,
Beryllium Is sole corundum coloring agent by Victoria Gomelsky, National
Jeweler, 17 Sept., 2002
still on over Thai stone treatment by Somporn Thapanachai, Bangkok
Post, 18 Sept., 2002
Gems & Gemology: Bulk diffusion–treated
sapphire with synthetic overgrowth by the GIA, posted
27 Sept., 2002
of corundum treatment greater than thought by Victoria Gomelsky, National
Jeweler, 25 Oct., 2002
traders in bid to take shine off orange sapphires by Supoj
Wancharoen, Bangkok Post, 15 Nov., 2002
of words between Thailand and AGTA goes public by Anthony DeMarco, JCK-Jewelers
Circular Keystone, posted 20 Nov. 2002
Gems & Gemology: An update on treated natural
corundum by the GIA, posted 20 Dec., 2002
gem dealers agree to disclose beryllium treatment by Cara Woudenberg, Colored
Stone, Posted Feb. 21, 2003
satisfied with Thai treatment by Somporn Thapanachai, Bangkok
Post, 8 March, 2003
diffusion of ruby and sapphire by John L. Emmett, Kenneth
Scarratt, Shane F. McClure, Thomas Moses, Troy R. Douthit,
Richard Hughes, Steven Novak, James E. Shigley, Wuyi Wang,
Owen Bordelon and Robert E. Kane, Gems & Gemology, Summer 2003, pp. 84–135.
(This article is the most complete to appear on the subject
method unique: GIA by Somporn Thapanachai, Bangkok Post, 25 August,
Note: Many of the articles that have appeared
in the Bangkok Post on this subject are filled with inaccuracies
and half-truths. We list them only for the record.
Below are articles that discuss previous cases of diffusion treatment
in Thailand, as well as other controversial Thai gem treatments.
- Coldham, T. (2002) Orange
sapphires or just lemons? Australian Gemmologist, Vol. 21, No. 7, pp. 288–293.
- Coldham, T. (2003) The history and importance
of heat treatment of Australian sapphire. Australian Gemmologist, Vol 21,
No. 11, September.
- Emmett, John L. and Douthit, Troy R. (1993) Heat
treating the sapphires of Rock Creek, Montana. Gems & Gemology, Vol. 29,
No. 4, pp. 250–272.
- Hänni, Henry A. (2001) Beobachtungen an
hitzegehandeltem Rubin mit künstlicher Rissheilung (Observations
on heat-treated ruby with artificially healed fissures). Zeitschrift
der Deutschen Gemmologischen Gesellschaft, Vol. 50, No. 3,
- Hänni, H.A. and Pettke, T. (2002) Eine neue
Diffusionsbehandlung liefert orangefarbene und gelbe Saphire (A new
diffusion treatment supplies orange and yellow sapphires). Gemmologie:
Zeitschrift der Deutschen Gemmolgigischen Gesellshaft, Vol. 51,
No. 4, 2002, pp. 137–152.
- Hughes, R.W. (1984) Surface repaired rubies. The
Australian Gemmologist, Vol. 15, No. 8, pp. 279–280.
- Hughes, R.W. (1987) Gem treatments: to disclose
or not to disclose. Gemological Digest, Vol. 1, No. 1, pp.
- Hughes, R.W. (1988) Reappearance of surface-diffusion
treated sapphires in Bangkok. ICA Lab Alert, No. 12, 2 pp.
- Hughes, R.W. (1991) There’s
a Rumble in the Jungle: The sapphire face-lift face-off
saga. Gemological Digest, Vol. 3, No. 2, pp.
- Hughes, R.W. (1992) Devil’s
Advocate: Vampire blues: deep-diffusion treated sapphires. JewelSiam, No.
3, May-June, pp. 83–86.
- Hughes, R.W. and Galibert, O. (1998) Foreign
affairs: Fracture healing/filling of Möng Hsu ruby. Australian
Gemmologist, Vol. 20, No. 2, April–June, pp. 70–74.
- Kane, R.E., Kammerling, R.C. et al. (1990) The
identification of blue diffusion-treated sapphires. Gems & Gemology, Vol. 26,
No. 2, Summer, pp. 115–133.
- Schmetzer, K., Bosshart, G., Hänni, H. (1983)
Naturally-colored and treated yellow and orange-brown sapphires. Journal
of Gemmology, Vol. 18, No. 7, July, pp. 607–622.