GRADING SYSTEM

This explains the 4Cs of Diamonds - cut, color, clarity, and carat weight - the most important characteristics to understand when making a diamond purchase.


Diamond

SIZE RANGE

Carat reflects the weight of the stone, which includes depth, height and diameter of the stones.
Size Size Range
+0.30 0.30 TO 0.399
+0.40 0.40 to 0.499
+0.50 0.50 to 0.699
+0.70 0.70 to 0.899
+0.90 0.90 to 0.999
+1.00 1.00 to 1.499
+1.50 1.50 to 1.999
+2.00 2.00 to 2.499
+2.50 2.50 to 2.999
+3.00 3.00 to 3.999
+4.00 4.00 to 10.999
Purity Description
FL Flawless
IF Inernally Flawless
VVS1 Very Very Slightly Included-1
VVS2 Very Very Slightly Included-2
VS1 Very Slightly Included-1
VS2 Very Slightly Included-2
SI1 Slightly Included-1
SI2 Slightly Included-2
SI3 Slightly Included-3
I1 Included -1

Diamond

CLARITY

Clarity is a term used for describing the number and size of inclusions in a diamond. Inclusions are mainly traces of non-crystallized carbon that may appear on the diamonds internally or externally. A flawless diamond contains no inclusion and is considered extremely rare and valuable. Large inclusions affect the brilliance of the stone as they interfere with the dispersion of light.

Additional comments for certified stones.

  • If our Clarity grading is VS-2 and laboratory gives us SI-1 certificate, we have to specify the exclusive clarity in the comment column.
  • If our Clarity grading is SI-1 and the laboratory gives us a VS-2 certificate, we have to specify the upgraded clarity in the comment column.

Diamond

COLOR

Diamonds close to being colorless are more rare and valuable. Diamonds that display little color allow more light to pass through, resulting in a burst of brilliance. On the basis of color, diamonds are allocated a grade, starting with D grade (for colorless diamonds) and ending in a Z+ grade. Some diamonds are also found in vivid colors such as red, blue and pink.

Additional comment for Certified stones.

  • If our color grading is G and the laboratory gives us H certificate, we have to specify exclusive color in the comment column.
  • - If our color grading is H and the laboratory gives us G certificate, we have to specify upgraded color in the comment column.

Color Grades Parameters
D E F Colorless
G H I J Near Colorless
K L M Faint
N to R Very Light
S to Z Light
Cut Grades Description
EX Excellent Cut
VG Very Good Cut
G Good Cut
F Fair Cut

Diamond

CUT

Cut gives a unique sparkle and brilliance to diamonds. Cut quality depends on the craftsmanship of the diamond cutter. If a diamond has perfect color and clarity but the cut is poor, it will lose its brilliance.

Diamond

POLISH

Polish mainly describes the smoothness of the facets in a diamond. This is the last step in the diamond cutting procedure. Brilliance of a diamond can be enhanced with a smooth polishing of the facets.
Polish Grades Description
EX Excellent Polish
VG Very Good Polish
G Good Polish
F Fair Polish
Symmetry Grades Description
EX Excellent Symmetry
VG Very Good Symmetry
G Good Symmetry
F Fair Symmetry

Diamond

SYMMETRY

Symmetry refers to the alignment of the facets (surface conditions) in a diamond. Each facet needs to be of a consistent size and positioned opposite the corresponding facet. Poor symmetry misdirects the light that enters the diamond.

Diamond

HERAT & ARROWS

An impeccable round diamond with perfect angles is called ‘Heart and Arrows’ (H&A). These diamonds are graded with extra specifications under SGS. They are not included in the regular cut criteria as H&A diamonds are considered better than the most excellent cut diamonds.
H&A Grades Description
EX Excellent H&A (100%)
VG Very Good H&A (80%)
NONE Not a H&A
Luster Grades Description
EX Excellent Luster
VG Very Good Luster
G Good Luster
F Fair Luster

Diamond

LUSTER

Luster and brilliance are two most valued attributes of a diamond. Luster describes a diamond’s fire and sparkle. Depending upon the light reflected from the stone, SGS grades diamonds on the basis of two levels of luster.
Milky Grades Description
ML-1 Slightly Milky
ML-2 Medium Milky
ML-3 Heavy Milky

Level of Milkiness:

Milkiness is mainly a hazy inclusion in the diamond that appears white or grey in color. This haziness affects the brilliance of a diamond.

Diamond

FLUORESCENCE

When exposed to ultraviolet radiations, a diamond glows if it carries the characteristic of fluorescence. Black light is the most common source of UV exposure in which many diamonds give off a glowing blue coloration.
Fluorescence Description
N None Fluorescence
FNT Faint Fluorescence
MED Medium Fluorescence
STG Strong Fluorescence
VSG Very Strong Fluorescence
Black Inclusion Description
N None
B-PP Pin Point Black Inclusion
B-1 Minor Black Inclusion
Minor Black Inclusion Medium Black Inclusion

Diamond

BLACK INCLUSION (NATTS)

As compared to the total inclusions, we grade diamonds on the basis of black inclusions by determining the following categories:

We grade diamonds on the basis of black inclusions as compared to the total inclusions by determining the following categories:

We specify two kinds of black inclusions.

  • Table black inclusion
  • Side black inclusion

Diamond

OTHER INCLUSION

Diamonds at SHRIHK are graded on the basis of five types of Inclusions. Pin Points (PP), Clouds (CLD), Crystals (CRL), Feathers (FR) and Spreaded (SPR).

  • Pin Point (PP): It is a small crystal that looks like a tiny dot when using a 10x loupe. Generally, pin points are white in color; however, they can also be found in a dark color.
  • Clouds (CLD):This consists of various tightly grouped pin points. Some are quite dense (impossible to see with the naked eye) whereas others look like a light haze.
  • Crystal (CRL):It is a mineral crystal contained in some diamonds. Crystals can appear alone or in groups and they can be of any size and color.
  • Feather (FR):This is a general term used for any break in the diamond.
  • Spreaded (SPR):This appears when the feather inclusions are in a greater number. They are spread across and not grouped together.

We specify two part of other inclusions.

  • Table other inclusion
  • Side other inclusion

Other Inclusion Description
SPR-2 Spreaded Medium Inclusion
SPR-3 Spreaded Heavy Inclusion
FR-1 Feather Minor Inclusion
SPR-1 Spreaded Minor Inclusion
FR-2 Feather Medium Inclusion
FR-3 Feather Heavy Inclusion
CLD-1 Cloud Minor Inclusion
CLD-2 Cloud Medium Inclusion
CLD-3 Cloud Heavy Inclusion
Open Inclusion Description
N None
HL Hair Line Open Inclusion
SM Small Open Inclusion
MD Medium Open Inclusion
HV Heavy Open Inclusion

Diamond

OPEN INCLUSION

Open inclusion is the inclusion on the surface of a diamond. Under SGS, diamonds with open inclusions are graded as mentioned below:

We specify two part of open inclusion.

  • Table open inclusion
  • Side open inclusion

Diamond

EXTRA FACET

It is an extra facet that is placed on a diamond’s normal facet without considering the symmetry of the stone. These are additional to the facets required for making a brilliant cut diamond.

Here’s an extra specification for the internal graining in the comment column:

  • Slight Internal Graining
  • Heavy Internal Graining

Other Inclusion Description
N None
P_SM Pavilion Small
P_MD Pavilion Medium
P_MJ Pavilion Major
P_HV Pavilion Heavy
C_SM Crown Small
C_MD Crown Medium
T_SM Table Small