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The
Gemological Institute of America constantly strives to remain on top of
issues that can affect the gem and jewelry industry and the public. When
we became aware of the U.S. Postal Service's proposed "sanitization"
of mail using ionizing radiation,we immediately began investigating the
potentail impact of this process on gems shipped through the USPS.Such
laboratory research is part of GIA's ongoing commitment to protecting
the public interest and maintaining high professional standard throughout
the gem and jewelry industry.
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The jewelry industry relies heavily on the U.S. Postal Service
to ship gems and jewelry throughout the USA. At most are aware
, the recent incidences of people being infected by anthrax apores
sent through the mail has caused the USPS to seek ways to protect
postal employees and the public from this potential threat. One
part of this effort is to use a technique that actually kills
anthrax spores (and other biological agents ) in the mail as it
is being processed.
One
company with which postal service has contracted,SurBeam (a subsidiary
of Titan corp.), makes equipment designed to combat food-borne
pathogens such as salmonella. SurBeam provides a type of linear
accelerator that creates a beam of high-energy electrons. In effect
, they are using irradiation to kill the microorganism that often
contaminate food.
However,
we know that this type of ionizing radiation is often used intentionally
to change the color of some materials -- and could produce an
undesirable result as well. We at GIA and others in the trade
immediately recognized the potential impact of this development
on the jewelry industry and the consuming public , so we decided
to test the effect of the proposed postal irradiation process
on the gem materials. |
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Freshwater cultured
pearls before (top) and after (bottom) irradiation by current
postal sanitization procedures. |
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A
spokesman for SurBeam told us that the actual dosage being used by the
postal system is 56 kilograys,which is equivalent to 5.6 megarads. This
figure was later confirmed by Luara Smith,Quality Assuran ce Manager for
Titan Scan Technologies, another Titan corp. subsidiary,who agreed to
run tests for us under the same conditions that are being used by the
post office.
For
these initial test , we chose gem materials that , based on our many years
of experience and discussions with expert in the feild, we know to be
affected by irradiation in a sinificant way . This group consisted of
two types of cultuered pearls plus eight different gem species and a number
of varieties of those species--all of which were natural -- for a base
of different samples, as follows: |
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Diamond |
- |
near colorless |
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Of
course,there are many other gem materials that might be affected
by this process,and the same gem materials from different localities
or with chemical or structeral differrences might not respond
the same as our samples. We intend to follow up this initial study
with one that will encompass many other species as well as stones
of know geographic origin. We also added to this group a 14 karat
yellow gold ring ,to ressure the industry that gold jewelry would
not retain any residual radioactivity from this process.
We
made up three sets of these samples and placed them in boxes that
were packaged in the same manner that we routinely use to ship
gems from the GIA Gem Trade Laboratory. Because stones are often
shipped through the mail more than once(e.g., sent out on memo,returned
or sent to a manufacturer for mounting, and then sent back or
on to someone else), we asked to have one package scanned just
once, another scanned twice, and the third scanned four times
-- to see if the cumulative effect of multiple scans caused any
sinificant difference.
The
content of the boxes were identical,except there was only one
heavily included gray diamond. We placed yhis in the package that
was to receive four scans to see if it would retain any residual
radioactivity, as is often detected in irradiation black diamonds.
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Diamond |
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Gray (due to inclusions) |
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Kunzite |
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Morganite |
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Cultured Pearl |
- |
bead-nucleated freshwater |
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Cultured Pearl |
- |
tissue-nucleated freshwater |
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Quartz |
- |
colorless |
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Quartz |
- |
yellow (citrine) |
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Sapphire |
- |
light blue |
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Topaz |
- |
colorless |
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Tourmaline |
- |
near colorless |
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Tourmaline |
- |
light pink |
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Tourmaline |
- |
bi-colored green and pink |
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Zircon |
- |
colorless |
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Zircon |
- |
yellow |
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Zircon |
- |
green |
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Left to right : Kunzite before
Kunzite After Irradiation by current postal sanitization procedures. |
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Result
After
we retrieved the packages, we first checked for the presence of residual
radiation with a Victoreen model 290 radiation survey meter. This was
done on the upopened packages as well as on the individual samples. Fortunately,
no residual radiation was detected.
Next,
we examined all the individual stones for obvious change in appearance.
(Changes in spectra and analytical data will be addressed in the course
of future research). All of the gem materials other than diamond showed
a dramatic change in color,as described below: |
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Gem Material |
Before |
After |
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Diamond |
near colorless |
near colorless, no change |
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Diamond |
gray |
gray - no change |
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Kunzite |
pink |
green |
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Morganite |
brownish or orangy pink |
yellow |
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Cultured Pearl (saltwater) |
white |
gray |
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Cultured Pearl (freshwater) |
white |
gray |
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Quartz |
colorless |
brown |
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Quartz |
yellow |
brown |
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Sapphire |
light blue |
yellowish orange |
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Topaz |
colorless |
brown |
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Tourmaline |
near colorless |
light pink |
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Tourmaline |
light pink |
darker pink |
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Tourmaline |
bi-colored green |
green - no change |
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and pink |
pink - darker |
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Zircon |
colorless |
pinkish brown |
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Zircon |
yellow |
yellowish brown |
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Zircon |
green |
(greenish) |
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yellowish brown |
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We
did not separate out the results for one ,two, or four scans because,
for most of the samples, the changes were just as dramatic in the box
that went through only one scan as in the box that went through four.However,
the degree of change was different for some stones. For examples, the
colorless quartz in the box that was scanned once came out a medium brown;
a similar sample in the box scanned twice turned dark brown; and the third
sample, scanned four times, became almost black. For the other gems, there
was no visible difference related to number of scans. GIA has absorption
spectra on the three near-colorless diamonds that were irradiated by Titan
Scan Technologies using the same process currently being by the USPS to
"Sanitize" mail. All three diamonds (which were sawn half octahedrons)
are type la; two were assessed as "J" color and the the third,
"I". Using a spectronic Unicam model UV-540, UV-VIS spectrophotometer,
we ranultraviolet-visible spectra at cryogenic temperatures on these samples
both before and after they went through the sanitization process. This
was done to document any potential change in the 200-850 nm spectral range,
the region where radiation-related absorption features occur in diamond.
The spectra showed that all three were typical Cape series diamonds with
relatively weak N3 centers (415 nm) and no other relevant features.
As we
expected, given our knownledge of the typical effect on diamonds at radiation
dosage used, there were no detectable changes in the spectra. In particular,
no radiation-related spectral featured had been added. Also, as indicated
in the earlier entry, there was no perceptible change in color (as determined
by experienced graders) either.
Other
colors and types of diamonds will be included in GIA's ongoing research
into the potential impact of postal irradiation procedures on gem materials. |
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Implications
for the future
Currently,
the U.S. post office is scanning only a small portion of the mail
and only letters and flat envelopes. John Dunlap, Manager of Materials
Handing and Deployment for the USPS Engineering Group, which oversees
mail sanitization operations, told us that "Probably nothing
will be done to packages that are sent registered or certified [the
preferred method for the jewelry industry], since we now require
information from the sender." Other postal authorities have
commented that the cost and time required to scan all mail would
be prohibitive.
We
also contacted the U.S. Customs Service, Brinks, Malca Amit, UPS,
and Federal Express to see if they were curretly using sanitization
procedures or had plans to do so. They all stated that no irradiation
procedures were being used or were planned at this time. They all
have imposed stricter limitations with letter, and some of the shippers
are no longer transporting envelopes. Nevertheless, it is important
that members of the trade and the consuming public alike be aware
that some gem materials could be affected by the procedure, and
every effort should be made to ship such materials by methods that
are not likely to be exposed to the sanitization process.
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Sapphire
before (top) and after (bottom) irradiation by current postal sanitization
procedures.
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Note,
too, that some of the color changes seen in our samples would not
be permanent. Some of these colors will fade with exposure to light
back to their original colors.
Others
can be changed back with heat. Still others will never revert to
their original color. (For more on the color stability of irradiated
gems, see K Nassau, "Gemstone Enhancement," 2nd edition,
Butterworth-Heinemann, OXford, 1994).
Also
as mentioned above, not all members of the same species or even
the same variety will react similarly. For example, according to
Dr George Rossman of the California Institute of Technology, it
is likely that darker blue sapphires and almost certainly those
from basaltic deposits such as Thailand or Australia-will not change
at all.
We
recognize that other gem species or varieties, including ruby and
emerald, may be affected to lesser degress by this radiation dosage.
In the second phase of our testing, which is already underway, we
hope to answer this and many more questions about this newest concern
to the industry.
For
background information on commercial irradiation of gem materials,
see C E Ashbaugh, "Gemstone Irradiation and Radioactivity,"
in "Gems & Gemology," Winter 1988, pp. 196-213. For
more on the possible effects of postal sanitization on gem materials,
see the upcoming Winter 2001 issue of "Gems & Gemology."
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