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Gemstone
Enhancement Codes (based on AGTA guidelines) |
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B
Bleaching
|
The
use of heat, light and/or chemicals or other
agents to lighten or remove a gemstone's
color.
This
is often accompanied by subsequent dying
and/or impregnation.
Example:
bleached
cultured pearl; bleached/impregnated jadeite |
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C
Coating
|
The
use of such surface enhancements as lacquering,
enameling, inking, foiling, or sputtering
of films to improve appearance, provide
color or add other special effects.
Example:
coated
diamond, coated topaz (mystic topaz) |
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D
Dyeing
(Staining)
|
The
introduction of coloring matter into a gemstone
to give it new color, intensify existing
color or improve color uniformity.
Example:
dyed
green jadeite |
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E
Normally
Enhanced
|
The
"E" symbol is used for gemstones
that are routinely enhanced.
Since
many enhancements are difficult or impractical
to prove definitively, unless otherwise
indicated, our approach is to assume that
such enhancements have been applied to that
particular gemstone.
This
assumption is made to protect both buyer
and seller.
If
a more specific method of enhancement is
known, then the specific enhancement code
will be used. |
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F
Filling
|
The
filling of surface-breaking cavities or
fissures with colorless glass, plastic,
or some similar substance.
This
process will improve durability, appearance
and/or weight.
Example:
ruby |
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FH
Flux
healing
|
During
heat enhancement, fluxes (or heat alone)
may be used to heal fractures/fissures which
were formerly open.
The
process dissolves the walls of the fractures
and redeposits the molten gem material,
healing the fractures closed.
Example:
ruby
(particularly that from Mong Hsu, Burma) |
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H
Heating
|
The
use of heat to alter color, clarity, and/or
phenomena.
Example:
Ruby,
sapphire, tanzanite, aquamarine, demantoid
garnet |
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HP
Heating
& Pressure
|
The
use of heat and pressure combined to affect
desired alterations of color and/or clarity. |
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I
Impregnation
|
The
impregnation of a porous gemstone with a
colorless agent (usually plastic) to give
it durability and improve appearance.
Example:
Stabilized
turquoise. |
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L
Lasering
|
The
use of a laser and chemicals to reach and
alter inclusions.
Example:
diamond |
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N
Not
Enhanced
|
The
"N" symbol is used to indicate
one of two situations.
First,
there are certain gemstones that are not
currently known to be enhanced (alexandrite,
some garnets, etc.)
Second
the "N" symbol may also be used
for a gem where it can be proved via gemological
or other means that a gem has not been subjected
to any enhancement. |
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O
Oiling/Resin
Infusion
|
The
filling of surface-breaking fissures with
a colorless
oil, wax, resin or other colorless substances,
except glass or plastic, to improve the
gemstone's appearance.
Example:
emerald |
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R
Irradiation
|
The
use of neutrons, gamma, ultraviolet and/or
electron bombardment to alter a gemstone's
color.
The
irradiation may be followed by a heating
process.
Example:
Blue
topaz, colored diamonds |
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U
Lattice
('bulk'
or 'surface')
Diffusion
|
Outside-in
diffusion of coloring chemicals via high-temperature
heat treatment to produce color and/or asterism.
Example:
lattice
diffusion-treated sapphire |
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W
Waxing/Oiling
|
The
impregnation of a colorless
wax; paraffin and/or oil in porous gemstones
to improve appearance.
Example:
jadeite |
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