SRK Grading
System (SGS)

At SRK, we have developed a comprehensive in-house grading system (SGS) that explains 16 diamond grading parameters down to the smallest detail. Based on years of research, we have designed this grading system for buyers who wish to read diamonds rather than just view.

With the help of our grading system details, our buyers can easily visualize the look of the diamond.

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Shape is an important factor to consider when buying diamonds. From princess cut, pear or oval shaped diamonds to heart shape, cushion, marquise-shape and emerald, every shape manufactured by SRK has its own attribute.

Pricing parameters followed by the SGS:

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

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.

We grade diamonds on the basis of purity by determining following categories:
  • FL
  • 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

Additional comment for Certified stone.
  • If our (SGS) 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 (SGS) 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.

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.

SGS Color Grades
  • DEF
  • G H I J
    Near Colorless
  • KL M
  • N to R
    Very Light
  • S to Z

Additional comment for Certified stone.
  • If our (SGS) color grading is G and the laboratory gives us H certificate, we have to specify exclusive color in the comment column.
  • If our (SGS) color grading is H and the laboratory gives us G certificate, we have to specify upgraded color in the comment column.

Cut gives a unique sparkle and brilliance to the 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.

We grade diamonds on the basis of cut by determining following categories:
SGS Cut Grades
  • EX
    Excellent Cut
  • VG
    Very Good Cut
  • G
    Good Cut
  • F
    Fair Cut

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.

Diamonds are graded on the basis of polish by determining following categories:
SGS Polish Grades
  • EX
    Excellent Polish
  • VG
    Very Good Polish
  • G
    Good Polish
  • F
    Fair Polish

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.

We grade diamonds on the basis of symmetry by determining following categories:
SGS Symmetry Grades
  • EX
    Excellent Symmetry
  • VG
    Very Good Symmetry
  • G
    Good Symmetry
  • F
    Fair Symmetry
Heart & Arrows

An impeccable round diamond with perfect angles is called “Heart and Arrows” (H&A). These diamonds are graded with extra specification under SGS. They are not included in the regular cut criteria as H&A diamonds are considered better than the excellent cut diamonds.

SGS H&A Grades
  • EX
    Excellent H&A (100%)
  • VG
    Very Good H&A (80%)
  • NONE
    Not a H&A

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:

Level of Brilliance:
SGS Luster Grades
  • EX
    Excellent Luster
  • VG
    Very Good Luster
  • G
    Good Luster
  • F
    Fair Luster

Level of Milkiness:

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

Such diamonds are further classified based on the magnitude of milkiness.

SGS Milky Grades
  • ML-1
    Slightly Milky
  • ML-2
    Medium Milky
  • ML-3
    Heavy Milky

When exposed to ultraviolet radiations, a diamond glows if it carries the characteristic of fluorescence. Black light is the most common source of UV in exposure of which many diamonds give off a glowing blue coloration.

SGS grades diamonds based on the level of fluorescence present in it:
SGS Fluorescence
Grades Description
  • N
    None Fluorescence
  • FNT
    Faint Fluorescence
  • MED
    Medium Fluorescence
  • STG
    Strong Fluorescence
  • VSG
    Very Strong Fluorescence
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:
SGS Black Inclusion
  • N
  • B_PP
    Pin Point Black Inclusion
  • B-1
    Minor Black Inclusion
  • Minor Black Inclusion
    Medium Black Inclusion

We specify two part of black inclusion
  • Table black inclusion
  • Side black inclusion
Other Inclusion

Diamonds at SRK 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 through naked eyes) 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 greater number. They are spread across and not grouped together.

SGS Other Inclusion
  • N
  • PP-1
    Pin Point Minor Inclusion
  • PP-2
    Pin Point Medium Inclusion
  • CLR-1
    Crystal Minor Inclusion
  • CLR-2
    Crystal Medium Inclusion
  • SPR-1
    Spreaded Minor Inclusion
  • 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

We specify two part of other inclusion
  • Table other inclusion
  • Side other inclusion
Open Inclusion

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

SGS Open Inclusion
  • N
  • HL
    Hair Line Open Inclusion
  • SM
    Small Open Inclusion
  • MD
    Medium Open Inclusion
  • HV
    Heavy Open Inclusion

We specify two part of open inclusion
  • Table open inclusion
  • Side open inclusion
Extra Facet

It is an extra facet 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.

SGS Extra Facet Grade
  • N
  • 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

Here’s an extra specification for the internal graining in the comment column:
  • Slight Internal Graining
  • Heavy Internal Graining