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I m p o r t a n t T e r m s
GIA Gemological Institute of
America—the leading independent Gemological laboratory in the U.S.A.
EGL European Gemological Laboratory—the leading independent
Gemological laboratory in the world.
AGS American Gem Society |
Color Grading Scale
Describes the amount of color the diamond contains. Ranges from colorless to
yellow.
Good color means no color. |
| EGL - GIA |
D E F |
G H I J |
K L M |
N O P Q R |
S T U V W X Y Z |
| |
COLORLESS |
NEAR COLORLESS |
FAINT YELLOW |
VERY LIGHT YELLOW |
LIGHT YELLOW |
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Clarity
Grading Scale
Describes the purity of the diamond. Most diamonds contain tiny natural
marks called identifying characteristics or inclusions.
The number of identifying characteristics or inclusions, their size, their
nature and location all affect the diamond’s clarity grade. |
| EGL - GIA |
FLAWLESS |
VVS1 VVS2 |
VS1 VS2 |
SI1 SI2 SI3 |
I1 I2 I3 |
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INTERNALLY FLAWLESS |
VERY VERY SLIGHT INCLUSIONS |
VERY SLIGHT INCLUSIONS |
SLIGHT INCLUSIONS |
IMPERFECT |
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Cut
Refers to the proportions, finish, symmetry and polish of the diamond.
These factors influence the fire, brilliance, sparkle and beauty of a
diamond.
This is the only C controlled by a person, how well the cutter has perfected
the cut.
Carat Weight
Diamond weight is measured in carats. Every carat is divided into 100
points.
For example, a 125 point diamond is 1 1/4 carats. |
| The 4 C’s are four variables that are used to
determine a diamonds value. Clarity:
Clarity is described as the clearness or purity of a diamond. This is
ultimately determined by the number, size, nature and location of the
internal identifying characteristics (inclusions) and external imperfections
(blemishes).
The following scale shows the different grades of clarity. |
| SYMBOL |
MEANING |
DEFINITION |
| F |
Flawless |
Free from all inclusions and blemishes |
| IF |
Internally Flawless |
No inclusions visible at 10x magnification |
| WS1 |
Very, Very Slightly Included |
Inclusions that are extremely difficult to locate
at 10x |
| WS2 |
Very, Very Slightly Included |
Inclusions that are very difficult to locate at
10x |
| VS1 |
Very Slightly Included |
Minor inclusions that are difficult to locate at
10x |
| VS2 |
Very Slightly Included |
Minor inclusions that are somewhat difficult to
locate at 10x |
| SI1 |
Slightly Included |
Noticeable inclusions that are easy to locate at
10x |
| SI2 |
Slightly Included |
Noticeable inclusions that are very easy to locate
at 10x |
| SI3 |
Slightly Included |
Some inclusions may be seen with the unaided eye |
| I1 |
Included |
Obvious inclusions. Somewhat easy to locate with
the unaided eye |
| I2 |
Included |
Obvious inclusions. Easy to locate with the
unaided eye |
| I3 |
Included |
Obvious inclusions. Very easy to locate with the
unaided eye |
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The above clarity grading scale is in accordance with the GIA
(Gemological Institute of America) and EGL (European Gemological
Laboratory) standards.
Buyer Beware!
There are two methods used to enhance the clarity grade
given to a diamond. They are laser drilling and fracture filling. Laser
drilling is the process in which a laser is used to drill a tiny hole into a
diamond and the dark inclusion or identifying characteristic is changed to a
light inclusion and fracture in filling, in which an inclusion is changed
from white to colorless. Neither process removes inclusions, so therefore
does not improve the clarity grade, but both improve the appearance” of the
diamond and may be very difficult to detect without proper equipment. Either
of these treatments must be disclosed to the customer prior to sale.
House of Jewels does not buy laser drilled or fracture filled diamonds
unless you request one. |
| Color: This “C”
describes the color the diamond contains. The range of color can go from
colorless to yellow with slight tints of yellow, gray or brown. Colors that
range from intense yellow to brown, blue, green, pink or red are called
fancy colors and are rare and therefore more valuable. At House of Jewels ,
we have access to tens of thousands of available diamonds from worldwide
sources with over night delivery. |
| EGL, GIA |
COLOR • COMMERCIAL GRADING |
| D, E, F |
COLORLESS (WHITE) |
| G, H, I, J |
NEAR COLORLESS (WHITE) |
| K, L, M |
FAINT YELLOW |
N, O, P, Q, R
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N, O, P, Q, R
REFLECTION. (A) |
| S, T, U, V, W, X, Y, Z |
LIGHT YELLOW |
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Buyer Beware!
It is possible to influence the color of a diamond by irradiation treatment
followed by heat treatment. This method is not recommended but is used to
change the color of a diamond. The draw back of this treatment is that you
risk color change over time. |
| Carat Weight: This
is the unit weight of the diamond. A carat is further subdivided into a 100
points (0.01 carat =1 point). One carat is equal to 0.20 grams. Value of
carat increases with carat size, because larger rough diamonds occur less
frequently. In other words, two half-carat diamonds taken together will not
cost as much as one one-carat diamond, as the one-carat stone is more rare.
Ten Facts You Need to Know Before buying a Diamond
- 1. Never compromise on the cut. Cut determines the brilliance of the
diamond
- Consider only certified diamonds by independent labs like AGS, GIA or
EGI
- Fluorescence—What is good and bad. Know the difference.
- Be aware of treated diamonds—clarity and color enhancement.
- Only buy loose diamonds. None of the 4 C’s can be determined in a
setting.
- Deal with an established reputable company, one who is a member of the
American Gem Society (AGS). Less than 5% of the jewelers in America meet
the high standards of this organization and are privileged to become
members.
- Avoid “sales” or other promotions. The only thing discounted is the
quality. How do you know what you’re getting.
- Know the return policy.
- Know the upgrade policy. No other jeweler offers 100% diamond
trade-in with no additional investment required. House of Jewels does.
- Make sure that everything is written down so you know exactly what you
are buying.
How a Diamond Handles Light
The way a diamond sparkles in the light is called its BRILLIANCE and
FIRE. These are not subjective terms, but can be scientifically defined.
As an example, if the same amount of light should fall on a pile of black
carbon powder as on a cut diamond. Both are formed from the same chemical,
but clearly they will handle that light in quite different ways.
Most of the light which falls on the powder is absorbed, which is why it
appears black. But when light strikes a diamond, part of the ray is
reflected from the surface. This is called EXTERNAL REFLECTION. (A)
The other part of the ray enters the diamond and, as it does so, it bends
due to the greater optical density of a diamond. This is called REFRACTION.
The light is then reflected from the internal surfaces of the diamond which
is INTERNAL REFLECTION. (B)
The ray then emerges from the top of the diamond where, once again, it is
bent or refracted and is separated into the colors of the spectrum. It is
this DISPERSION that gives the diamond its fire. (C)
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A
When a ray of light touches the surface of a diamond, part of the ray is
reflected back into the eye of the observer. This phenomenon is called
external reflection. |
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B
The rest of the ray of light penetrates the stone and is then deflected
towards the center of the diamond. This is known as refraction. The ray
reaches the internal surfaces of the diamond at points 1 and 2. This is
called internal reflection. The brilliance of the diamond depends on the
amount of internal and external reflections of light from the diamond to
the eye. |
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C
The ray of light is reflected to the surface of the stone where it is
seen as the colors of the spectrum (the “rainbow effect”). This
phenomenon is known as dispersion. The fire of the diamond is the
visible effect of dispersion. The sparkle is the flashing effect seen
when a diamond moves in the light. |
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| Cut: Refers to the
proportions, finish, symmetry and polish of the diamond. These factors
determine the fire and brilliance of the diamond. Well cut diamonds sell at
premium and poorly cut diamonds sell at discounted prices. With the advent
of new technology, the cut of the diamond can be etermined through the use
of the Sarin system, a computerized system which takes accurate measurements
and proportions of the diamond in seconds. Another way of calculating
measurement is the Leveridge Gauge. As an example, a round brilliant cut,
which has 58 facets, is shown below. Since the quality of the cut is
directly responsible for the stone’s beauty, the precision with which the
facets are arranges is of prime importance. They determine the amount of
light reflected to the eye, called brilliance. |
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The proportions displayed by the stone are very
significant. Two of the key factors in the grading of
the cut quality—table percentage and depth percentage—are usually expressed
on grading
reports. Measurement of three different parameters allows for easy
calculation of these percentages
by using the formulas expressed below. |
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Fine Cut
No loss of refracted light |
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Heavy Cut
Light is lost through sides |
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Shallow Cut
Light is lost through bottom (95% of diamonds) |
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Without attention to quality cutting, this is lost
and not returned to the eye. |
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