unit
of measure
conversions
equivalences



italiano

english




shape
and carat
SHAPE
In
addition to the traditional Round Brilliant shape, the most
common Fancy Shapes are: Oval, Pear, Marquise, Princess,
Radiant, Emerald and Heart. Less common shapes include Trillion
(or Triangular), Flanders, Asscher, Lily, Flanders Brilliant,
Asscher, Cushion, Half Moon, Trapezoids and Kite.

round


58
facets, 33 on the crown and 25 on the pavilion. 
oval


58
facet brilliant pattern, but can have a varying number of
pavilion main facets ranging from 4, 6 or 8. 
pear


58
facet brilliant pattern, but can be cut with different numbers
of pavilion mains of 8,7,6, or 4 facets. 
marquise


58
facet standard brilliant (33 crown, 25 pavilion), the same
as the round brilliant. However, the pavilion can be cut with
either 4,6 or 8 pavilion main facets. 
princess


50
facets (21 crown, 4 girdle, 25 pavilion) or 58 facets (21
crown, 4 girdle, 33 pavilion), depending on how the pavilion
is cut. 
emerald


58
facets (25 crown, 8 girdle and 25 pavilion). 
heart


is
a brilliant cut, which can be modified so that the number
of pavilion mains may be 6,7, or 8. 
trillion


The
cut is an adaptation of the radiant cut but it is in a triangular
shape. The trillion is a triangle that has equilateral sides
and is a combination cut of the step cut and the brilliant
cut diamond. 
CARAT
Carat is the measuring unit of diamond weight.
The definition of a carat has changed over time, but since
1913 the international standard has been 200 milligrams,
or 1/5 of a gram (1/142 of an ounce). One carat is divided
into 100 parts, called “points.” So, a 25point
diamond weighs a quarter carat and a 50point diamond weighs
a half carat. A diamond may be referred to as a 3/4carat
or 75point stone. Jewelers usually express diamond weights
in carats and decimals. A 1.09carat stone, for example,
is said to weigh “one oh nine carats” while a
0.99carat diamond weighs “ninetynine points.”
“Carat total weight” (Ct. T.W.) describes the
combined total weight of all the stones in a piece of jewelry
having more than one diamond.

Carats

0.75

0.80

0.85

0.95

1.00

1.25

1.50

1.75

1.90

2.00

mm

5.8

6.0

6.2

6.4

6.5

7.0

7.4

7.8

8.0

8.2

Two terms,
carat and karat are often confused. In the US, karat refers to
the fineness of gold alloys
(pure gold is 24 karat; 14 karat is 14 parts gold and 10 parts
other metals) and carat refers to gem weights.

Round 
Ct.
T.W. 
0.50 
0.75 
1.00 
1.25 
1.50 
2.00 
2.50 
3.00 
mm

5.0 
6.0 
6.5 
7.0 
7.5 
8.0 
9.0 
9.5 

Marquise 
Ct.
T.W. 
0.50 
0.75 
1.00 
1.25 
1.50 
2.00 
2.50 
3.00 
mm

7
x 4 
8
x 4 
10
x 5 
10.5
x 5.5 
11
x 5.5 
12
x 6 
13
x 6.5 
14
x 7 

Pear 
Ct.
T.W. 
0.50 
0.75 
1.00 
1.25 
1.50 
2.00 
2.50 
3.00 
mm

7
x 4 
8
x 5 
9
x 5 
9.5
x 5.5 
10
x 6 
11
x 6.5 
12
x 7 
13
x 8 

Oval 
Ct.
T.W. 
0.50 
0.75 
1.00 
1.25 
1.50 
2.00 
2.50 
3.00 
mm

6
x 4 
6.5
x 5 
7.5
x 5.5 
8
x 6 
8.5
x 6.5 
9
x 7 
9
x 7.5 
10
x 8 

Emerald 
Ct.
T.W. 
0.50 
0.75 
1.00 
1.25 
1.50 
2.00 
2.50 
3.00 
mm

6
x 4 
7
x 4.5 
7
x 5 
8
x 5 
8.5
x 5.5 
9
x 5.5 
9.5
x 6 
10.5
x 6 

Round 
Ct.
T.W. 
0.01 
0.015 
0.04 
0.055 
0.11 
0.18 
0.25 
0.35 
mm

1.3 
1.5 
2.0 
2.5 
3.0 
3.5 
4.0 
4.5 

Baguette 
Ct.
T.W. 
.035 
0.05 
0.06 
0.075 
0.11 
0.15 
0.20 
0.25 
mm

2.0 
2.5 
3.0 
3.5 
4.0 
4.5 
5.0 
5.5 

Trillion 
Ct.
T.W. 
0.10 
0.12 
0.15 
0.25 
0.30 
0.40 
0.50 
1.0 
mm

3.0 
3.5 
4.0 
4.5 
5.0 
5.5 
7.0 
9.0 

Princess 
Ct.
T.W.
 0.05 
0.10 
0.15 
0.25 
0.30 
0.45 
0.60 
1.00 
mm

2.0 
2.5 
3.0 
3.3 
3.5 
4.0 
5.0 
6.0 
note:
the weights and sizes shown are approximate!

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