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Carat
The unit of measurement used to describe the weight of diamonds is called 'Carat'.
The 'Carat' weight is commonly expressed in points or fractions.
1 carat is equal to 0.2 grams, or 0.007 ounces.
5 carats is equal to 1 gram.
141.7 carats is equal to 1 ounce.
There are 100 points in 1 carat. For instance, 0.33 carats is generally expressed
as 33 points, or 1/3 of a carat.
Carat means weight of diamond which reflects its size. One carat diamond weighs
100 cents.
(1 ct = 100 cents ) Diamond sizes can be expressed by its weight (unit), pointers
or stones per carat.
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Price consideration with Size Range.
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Weight (unit): 1ct=100 cents 5cts = 1.000gms
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CUT (PROP)
Diamond's beauty depends upon optical properties such as high Refractive index,
color dispersion, luster & high degree of clarity. We give strong thrust on
cut grading. Due to well equipped manufacturing system our stones are best polished.
Luster means fire of diamonds. Better the Polish, brighter & more lustrous the
stone. At the time of cutting take care that the light entering from top should
not be lost through the teak pavilion sides. So Customer gets to observe almost
100% light from a round brilliant cut diamond. i.e. (82-83% from total internal
reflection & 17 -18 % from luster). This phenomenon is known as "LIFE". As diamond
critical angle is 24*, brilliance of diamond depends upon pavilion facets &
pavilion angle. Cut determines brilliance. In RBC diamond Crown facets act like
small prism, which split white light. Small crown gives less Dispersion & more
Brilliance vice versa.
Lay people often confuse a diamond's SHAPE with its CUT; this is most likely due
to the industry's synonymous use of the terms "cut" and "shape" to describe a diamonds
shape (outline), i.e. marquise cut, round brilliant cut, or pear shape. In reality
when we refer to the "cut" or "make" of a diamond, we are really referring to a
compilation of three factors. It’s PROPORTIONS in terms of degrees and percentages...
the quality of its POLISH or finish... and the SYMMETRY of its facets... These three
factors result in the "Overall Cut Grade" of the diamond.
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Code
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Description
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Image
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(ID) IDEAL
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Ideal cut diamonds are round diamonds that have been cut to exact, mathematical
proportions. It must be symmetrical, and have 58 facets, placed exactly according
to formula. These diamonds are cut to maximize the brilliance and sparkle of the
stone.
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(EX+) EXCELLENT+
(EX) EXCELLENT
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This cut is intended to maximize brilliance and is as near to ideal proportions
as possible. The typically smaller table sizes of these diamonds have the added
benefit of creating a great deal of dispersion - or 'fire' - as well.
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(VG+) VERY GOOD+
(VG) VERY GOOD
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This cut deviate slightly from the Excellent cut proportions in order to create
a larger diamond. However, diamonds in this category reflect the majority of the
light that enters them, creating a good deal of brilliance
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(GD+) GOOD+
(GD) GOOD
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Diamond in this category will reflect much of the light that enters them. Their
proportion falls outside of the preferred range because the cutter has chosen to
create the largest possible diamond. Good cut diamonds offer an excellent cost-saving
without sacrificing quality or beauty.
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(FR+) FAIR+ (FR) FAIR
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A diamond graded as Fair will be cut to a lower standard that reflects only a small
proportion of the light that enters it as compared to Good cut diamonds, losing
fire and brilliance.
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Clarity Grade |
Table Inclusion | Black Inclusion |
Opens | Type of Inclusion | Knot
| Graining | Eye Clean
Opens (OP)
This term is used to indicate open position in diamond if there is any open on the
surface of diamonds. This is subdivided in three parts: - (1) OPTA = Open on Table,
(2) OPCR = Open on Crown, (3) OPPV = Open on Pavilion.
Open on Table (OPTA)
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Code
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Description
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(O1) – VERY SMALL
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Difficult to see and it is dependent on the clarity grade.
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(O2) – SMALL
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Easy to see as compared to very small and it is dependent on the clarity grade.
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(O3) - HEAVY
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Easily seen and it is dependent on the clarity grade.
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Open on Crown (OPCR)
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Code
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Description
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O1 – VERY SMALL
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Difficult to see and it is dependent on the clarity grade.
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O2 – SMALL
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Easy to see as compared to very small and it is dependent on the clarity grade.
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O3- HEAVY
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Easily seen and it is dependent on the clarity grade.
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Open on Pavilion (OPPV)
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Code
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Description
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O1 – VERY SMALL
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Difficult to see and it is dependent on the clarity grade.
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O2 – SMALL
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Easy to see as compared to very small and it is dependent on the clarity grade.
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O3 - HEAVY
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Easily seen and it is dependent on the clarity grade.
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These ratings are dependent on the maximum Open for every diamond in each clarity
grade and are visible with 10X magnification.
KNOT
A "knot" is an included diamond crystal that extends to the surface of the diamond.
In other words, it is a diamond crystal which reaches the polished surface of a
finished diamond. With proper lighting and magnification you may be able to see
the boundary between the knot and the diamond which contains it. Knots sometimes
resemble raised areas on a facet surface or group of facets. Differences in the
polish quality may be visible on the surface of the knot and the facet where it
is located. We typically reject diamonds for this characteristic because we feel
that knots provide a potential durability risk to the longevity of the diamond.
The first picture below shows a knot as seen through our Gem Scope using a normal
light source; we diffused the light source for the second picture to provide you
with a different perspective of the inclusion.
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Code
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Description
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Y – YES
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KNOT is present in diamond.
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Graining
Graining is divided in to two parts namely Internal graining (IG)
and surface graining (SG). Internal inclusion of irregular crystal
growth may appear milky like faint lines or streaks, or may be colored or reflective.
The inclusions or graining that appears on the surface of the diamond is known as
surface graining.
The comment on a lab report indicating "Internal Graining Not Shown" should not
be reason for alarm because it refers to clarity characteristic which is usually
not readily visible without the use of extremely high magnification. Internal Graining
should not be considered an "absolute characteristic" because the visibility depends
on the lighting conditions and the specific angle by which the diamond is being
evaluated. It might be visible to an experience diamond grader who is examining
the diamond under laboratory conditions, but may never be detected by other people.
Essentially internal graining refers to part of the grain structure of the diamond
which was visible as a kind of transparent line to the grader. The degree of the
visibility of the grain lines will have an effect upon the clarity grade of the
diamond and if no other clarity characteristics are present then the graining may
be the basis for the clarity grade of the diamond. For instance, a diamond that
contained small diamond crystals which by themselves would warrant a clarity grade
of VS-1 might be graded as a VS-2 if internal graining were present. However another
diamond that did not contain the diamond crystals might be graded as VVS-2 if the
grade is based upon internal graining and the comment "clarity grade based upon
internal graining" would appear under the "comments" section of the lab report while
nothing is indicated under the "keys to symbols" by the plotting diagram. This series
of photographs shows the very subtle effect of internal graining as seen within
a diamond we purchased for inventory at various degrees of magnification. Notice
how the internal graining is not readily visible in the first picture which was
taken using a magnification level of about 20x. The internal graining is barely
visible in the next two photographs which were taken of the table facet at about
40x magnification, the grain line appears as a kind of translucent line as indicated
by the light blue arrows. We increased the magnification substantially for the remaining
pictures which show the internal grain line as seen through our Gem Scope using
normal and diffused light sources.
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Code
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Description
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IG – Internal Graining
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Diamond has internal graining
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SG- Surface Graining
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Diamond has surface graining
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Eye Clean
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Code
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Description
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Image
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E1 – Eye Clean
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Diamond that has no inclusion visible to the naked eye. We describe it in clarity
grade SI1 and down. Stones having clarity VS2 and above always falls in this criteria.
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E2 – Semi Eye Clean
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These diamonds have inclusions which are visible to trained naked eyes as compared
to Eye Clean diamonds.
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These ratings are dependent on the maximum inclusions for every diamond in each
clarity grade and visible with naked eye.
Color Scale |
Color Shade | Fancy Colored Diamond
Color Scale
Diamonds act as prisms, dividing light into a spectrum of colors and reflecting
this light as colorful flashes referred to as a diamond's 'fire'. The more colorless
a diamond is, the more vividly colorful the 'fire' will appear.
Diamonds come in every color of the spectrum, but the most popular gems are colorless.
Truly colorless, icy-white diamonds are extremely rare, and therefore, most costly.
Stones are graded by color and given designations dependent on how far they deviate
from the purist white.
The best way to see the true color of a diamond is by looking at it against a white
surface. Although the majority of diamonds come in shades of white, the gems also
come in a spectrum of majestic colors, from red and canary yellow to blue, green
and brown. These colorful diamonds, known as fancies, are valued for their depth
of color, just as white diamonds are valued for their lack of color.
Grades in the color of diamonds range from D - Z. D is being truly colorless and
of the highest quality. E and F are also graded as colorless while G, H, I and J
are near colorless. Diamonds graded K, L and M will have obvious hints of color
and as the scale approaches P, you may find subtle changes in hue and tone. The
exceptions to the rule are 'Fancy' diamonds in well-highlighted colors that include
pink, blue, red, green
and canary yellow. These are particularly rare and highly treasured.
Types of color
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D
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Absolutely colorless. The highest color grade, which is extremely rare.
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E+
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Colorless nearly to D color
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E
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Colorless. Only minute traces of color can be detected by an expert gemologist.
A rare diamond.
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F+
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Colorless nearly to E color
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F
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Colorless, Slight color detected by an expert gemologist, but still considered a
'colorless' grade. A high-quality diamond.
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G+
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Colorless nearly to F color
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G
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Near-colorless. Color noticeable when compared to diamonds of better grades, but
these grades offer excellent value.
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H+
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Near colorless close to G color
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H
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Near-colorless. Slightly off-white when compared to diamonds of better grades but
these grades offer excellent value.
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I+
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Near colorless close to H color
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I
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Off-white when compared to diamonds of better grades. Color slightly detectable.
A very good value stone.
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j+
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Off-white diamond but close to I color.
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j
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Light color detectable with 10x diamond loupe. A very good value stone.
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k+
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This diamond is very close to J color diamond but not exactly J color
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k
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Light color detectable by the naked eye. A very good value stone.
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L+
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This diamond is very close to K color diamond but not exactly K color
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L
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Noticeable color. The color is detectable by the naked eye. A very good value.
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M+
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This diamond is very close to L color diamond but not exactly L color diamond
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M
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Clearly visible color. Detectable with naked eyes. A very good value.
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N+
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Clearly visible color. Detectable with naked eyes. A good value.
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N
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This diamond is very close to N+ color diamond but not exactly N+ color diamond
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O+
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Clearly visible color. Detectable with naked eyes.
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O
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This diamond is very close to O+ color diamond but not exactly O+ color diamond
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Color shade
Many a times it’s been noticed that a stone has a color shade apart from its actual
color to give you a brief idea of the same we have different color shades
Fancy Colored Diamonds
Certain diamonds are called 'Fancies'. These stones have intense natural colors
that in some cases are very rare and command exceptional values. These stones are
not color graded with the scale above. Brown and yellow diamonds are the most common
members of the Fancy group and have a distinct beauty of their own. Reds, blues
and greens are extremely rare and highly sought after by designers and collectors.
Colors are available in Blue, Brownish Pink, Grayish Black, Green Pink, Pinkish
Brown, Yellowish Brown, Yellowish Green, White, Off White, Yellow and Brown.
Fancy colors are generally graded and categorized as following
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