CARAT

 

DIAMOND CARAT GUIDE

0.25
Ct.

Round

4.1
mm
0.50
Ct.

Round

5.1
mm
0.75
Ct.

Round

5.8
mm
1.00
Ct.

Round

6.4
mm
1.50
Ct.

Round

7.4
mm
2.00
Ct.

Round

8.1
mm
3.00
Ct.

Round

9.3
mm
4.00
Ct.

Round

10.2
mm
5.00
Ct.

Round

11.25
mm
 

CARAT SIZE

 
+0.18
0.180 to 0.229
+0.23
0.230 to 0.299
+0.30
0.300 to 0.399
+0.40
0.400 to 0.499
+0.50
0.500 to 0.699
+0.70
0.700 to 0.899
+0.90
0.900 to 0.999
+1.00
1.000 to 1.499
+1.50
1.500 to 1.999
+2.00
2.000 to 2.999
+3.00
3.000 to 3.999
+4.00
4.000 to 4.009
+5.00
5.000 to 5.999
+6.00
6.000 to 6.999
+7.00
7.000 to 7.999
+8.00
8.000 to 8.999
+9.00
9.000 to 9.999
+10.00
10.000 to 10.999
 

color


White Color

yellowish

brown

Pink

Grey

Green

 

Diamond Color Guide

  • D   E
  • F   G
  • H   I
  • J   K
  • L   M
  • N   O - P

 

 

Premium White

White

Tinted White

Slightly Tinted

Faint Yellow
 

CLARITY

The clarity grading of a Diamond is based on the number of inclusions and range from internally flawless to I3 (many internal inclusions) and we grade the Diamonds based on the following internationally accepted criteria.

 
FL
Flawless
IF
Internally Flawless
VVS1
Very very slightly included 1
VVS2
Very very slightly included 2
VS1+
Slightly better than VS1
VS1
Very slightly included 1
VS2+
Slightly better than VS2
VS2
Very slightly included 2
SI1+
Slightly better than SI1
SI1
Slightly included 1
SI2+
Slightly better than SI2
SI2
Slightly included 2
SI3+
Slightly better than SI3
SI3
Slightly included 3
I1+
Slightly better than I1
I1
Included 1
I1-
Slightly lower than I1
12+
Slightly better than I2
I2
Included I2
I2-
Slightly lower than I2
I3+
Slightly better than I3
I3
Included I3
 

 

 
  • if

internally flawless
  • VVS1   VVS2

very very slightly included
  • VS1   VS2

very slightly included
  • si1   si2   si3

slightly included
  • i1   i2   i3

imperfect
 

DIAMOND MEASUREMENT

 

Diamond cut

 

excellent

very good

good

fair
 

symmetry

Symmetry refers to the exactness of the shape and arrangement of facets and can be affected by the following factors:

off-round

Deviation from the circular shape of a round diamond.
off-center: culet

Deviation from the culet from the central position on the pavilion.
girdle thickness variation

Variation of the girdle thickness at the bezel positions.

 

off-center table

Deviation of the table from the central position of the crown.
table/ culet alignment

Displacement of the table facet and culet in opposite directions.
table size variation

Differing table size measurements indicating non-octagonal table.

 

Based on the factors above, we grade symmetry Under 10 X magnification as follows:

 
EX
Excellent Symmetry
VG
Very Good Symmetry
GD
Good Symmetry
FR
Fair Symmetry
 

POLISH

Polish is a measure of the smoothness of the facets on the Diamond and can be affected by any of the following:


abrasion

scratches

burn marks

 


nicknick

polishing lines

 

Other features which affect polish are:

Pit, Transparent Polishing Lines, Dop Burn, Rough Girdle, Laser Groove.

 

We grade the polish finish (Under 10 X magnification) with the following criteria:

 
EX
Excellent Polish
VG
Very Good Polish
GD
Good Polish
FR
Fair Polish
 

HEARTS & ARROWS

 
diagram 1

(Heart Image)
diagram 2

(Arrow Image)
 

 

The term Hearts and Arrows relates to a stone having perfect proportions and symmetry. When perfectly polished, the diamond displays Heart shaped reflections when looking from the Pavilion (Diagram 1) and Arrow shaped reflections when looking from the Table (Diagram 2)

 

Based on the factors above, we grade Heart & Arrow as follow:

 
ID
Ideal Hearts & Arrows
EX
Excellent Hearts & Arrows
VG
Very Good Hearts & Arrows
 

FLOURESCENCE

To measure fluorescence diamonds are exposed to ultraviolet light. This light will indicate the extent of fluorescence in Diamond. The pictures below show the different grades of fluorescence. We grade fluorescence by Comparing with fluorescence masters for accurate results

 

Star Rays Grades Fluorescence with UV light and Compare with fluorescence master Stones for accurate results.

 
N
None
F / VSL
Faint / V.Slight
M / SL
Medium / Slight
STG
Strong
V.STG
Very Strong
 

LUSTER

Luster is a way of measuring how the light interacts with the surface of the stone.
We use our experienced in house gemologists to assess the degree of luster.
When a stone has a cloudy effect, we grade this with the term Milky luster.

 

We grade under as follows:

 
EX
Excellent Luster
VG
Very Good Luster
ML - 01
(ML-01) Minor Milky Luster
ML - 1
(ML-1) Slight Milky Luster
ML - 2
(ML-2) Medium Milky Luster
ML - 3
(ML-3) Heavy Milky Luster
 

OPENS

Open is a very small unpolished section of a diamond which affects its polished finish. Opens can be Nick, Cavity or Percussion mark, knot, Etch Channel, Bruise & pit. When grading Diamonds we define an Open according to where it is located on the Diamond. It can be on the Table, Crown, Girdle or Pavilion.

The different facets of a round brilliant cut diamond

 

We grade opens as follows:

 
N
None
V.S
V.Small
S
Small
MED
(Medium
L
Large
 

INCLUSION PATTERN

The inclusion pattern defines the extent and proportion of inclusions in the diamonds. The grading criteria range from minor inclusions (scattered) to major inclusions (high concentration)

 
NA
Not Applicable
NC
Not Concentrated
S1
Scattered 1
S2
Scattered 2
C1
Concentrated 1
C2
Concentrated 2
C3
Concentrated 3
 

 

 

NA

NC

S1

S2

C1

C2

C3
 

CULET

A polished diamond has 57 facets and the Culet (the tiny facet or point at the base of the pavilion) The culet may vary in size that in turn can impact the brilliance of the polished stone, so we grade the Culet from Pointed (excellent) to chipped.

 
N
None
V.S
Very Small
S
Small
MED
Medium
 

 

 

None

V.Small

Small

Medium
 

BLACK INCLUSION

Natts are black colored crystals, graphite or hematite within a diamond. Higher the number of Natts inclusions within a diamond greater is its impact on the clarity and luster. We grade Natts according to its concentration, position and size.

 
  Black in Table (BIT) Black in Crown (BIC)
NO Black N0 N0
Minor Black N01 N01
Small Black N1 N1
Medium Black N2 N2
Major Black N3 N3
 

 

 

NO

NO1

N1

N2

N3
 

TABLE & CROWN INCLUSION

A diamond is graded by looking through the top (the Table), where it is possible to obtain the complete picture of its clarity. We grade diamonds on this basis to identify Table and Crown inclusion.

 

T01-C01

T2-C1
 

 

 
  Table Inclusion
T0 Clean Table
T01 Minor Inclusions
T1 V. Slight Inclusions
T2 Slight Inclusions
T3 Medium Inclusions
T4 Heavy Inclusions
  Crown Inclusion
C0 Clean Table
C01 Minor Inclusions
C1 V. Slight Inclusions
C2 Slight Inclusions
C3 Medium Inclusions
C4 Heavy Inclusions
 

 

For example: A low number of inclusions is graded as 0, and high number of inclusions is graded as 4.

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