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A diamonds color grade
tells how much color is
in the diamond. A
diamond that is totally
colorless is worth more
than a diamond with a
hint of color. Color
grades range from a
colorless “D” grade up
to a yellow/brown color
“Z”. Any diamond with
more color than "Z" is
graded as "Fancy
Color". Fancy Colored
diamond and are valued
lower than white
diamonds of the same cut
and carat.
The following chart
illustrates the color
characteristics of the
diamonds from colorless
to yellow/brown.
Color grading is done by
placing the diamond face
down and comparing them
to master stones under
special lighting.
Emerald and Asscher cuts
show more color than
ideal cuts such as round
brilliant. Some
diamonds may have
fluorescence, and is not
graded under Color. This
is made easily visible
under an ultraviolet
light source such as a
black light used in
special effects.
Diamonds with
fluorescence will glow
under an ultraviolet
light. Fluorescence can
be faint to very strong,
and the most common
fluorescent color is
blue. As blue is the
complimentary color to
yellow, the most common
tinted color in
diamonds, blue
fluorescence can make
yellowish diamonds look
white or colorless.
There are many methods
of enhancing diamond
colors. Some are to
whiten white diamonds
and others are to
enhance the color with
diamonds with
not-so-good color. At
Diamantbids.com, we
use color enhancement to
create fancy colored
diamonds only. We do
not use any methods to
raise the grades of
white diamonds. Such as
enhancing a “G” color
diamond to “E”. The
different methods we use
to enhance the color in
our diamonds are HPHT,
Irradiation and Surface
Enhancement. All our
items are clearly
labeled as Enhanced on
our item description.
High
Pressure, High
Temperature (HPHT)
HPHT is a process
developed by General
Electric in 1999 to
color treat diamonds.
This process puts over
60 kbar (nearly
1,000,000 psi) of
pressure on the diamond
at around 1400°C
(2550°F). Diamonds
treated with HPHT can
transform into many
colors including to
pinks and blues. HPHT
can also be used to
create white diamonds,
however
Diamantbids.com will
only use this process to
create fancy colored
diamonds. This
treatment is permanent
and will not be affected
by cleaning or heat from
setting repairs.
Irradiation (IRR)
Irradiation treatment
involves exposing the
diamond to
electromagnetic rays to
release electrons from
their normal location to
a more desirable
location changing its
color. Neutron
bombardment and electron
bombardment are the two
main irradiation methods
practiced today.
Diamonds treated by
irradiation produce many
brilliant colors such as
green, yellow, blue and
reds. This color
treatment is permanent
and will not be affected
during cleaning
processes. However, blue
or green enhanced colors
could change to a
yellowish color if high
heat, 300°C (572°F) or
more, is used during
setting repairs.
Surface
Enhancement (SE)
Surface Enhanced
diamonds are chemically
treated to change the
color of a diamond to
Brilliant colors. This
is done by coating the
diamond surface with a
metal halide. A similar
technique used to coat
some camera lenses that
create the blue
reflection. This method
can produce vibrant
pinks and cognac reds.
Care should be taken
with surface enhanced
diamonds. The coating
can wear out during
heavy cleaning or heat
from setting repairs.
Heat
Treatment (HT)
Heat Treatment or
'annealing' is done
using a combination of
chemicals (beryllium,
borax, lead, tantalum)
and heat to change the
diamond's color.
Heating or "cooking" the
diamond is done at
temperatures ranging
from 450ºC (842°F) to
1850ºC (3362°F) for 2 to
12 hours or more. We
only use this process to
create our black opaque
diamonds. To check if a
diamond has been
heat-treated, one way is
to look for the presence
of small fractures
within the stone that
appear around natural
mineral inclusions.
This treatment is
permanent and will not
be affected by cleaning
or heat from setting
repairs. |
