Cookson Jewellery Quarter Diamond Sizing Chart
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1Diamond Sizing Chart
Round Stones
Oval Stones
Princess Cut Stones
carat to mm
carat to mm
carat to mm
carat
mm
carat
mm
carat
mm
weight
size
weight
size
weight
size
0.005
1.0
0.20
4 x 3
0.06
2.0
0.01
1.3
0.25
5 x 3
0.08
2.25
0.015
1.5
0.33
5 x 3.5
0.10
2.5
0.02
1.7
0.40
5 x 4
0.13
2.75
0.025
1.8
0.50
6 x 4
0.15
3.0
0.03
2.0
0.65
6.5 x 4.5
0.20
3.25
0.035
2.1
0.75
7 x 5
0.23
3.5
0.04
2.2
1.00
7.5 x 5.5
0.25
3.75
0.05
2.4
1.25
8 x 6
0.30
4.0
Diamond
Fire Opal
Topaz
Cornelian
0.06
2.5
1.50
8.5 x 6.5
0.35
4.42
0.07
2.7
1.75
9 x 6
0.40
4.5
Formed under high temperatures and
These stones tend to have one body of
A symbol of love and affection, this clear,
Also known as Sadoine or Mecca Stone,
0.08
2.8
2.00
9 x 7
0.50
4.75
bright gemstone is believed to inherit its
pressure 50 miles or more underground.
colour, the most common of which is
the name Cornelian is derived from
0.09
2.9
2.50
9.5 x 7.5
0.63
5.0
The hardest mineral on earth, with its
name from the Sanskrit meaning, ‘fire’.
Carne, the Latin for ‘flesh’, due to the
reddish-orange, but they can range from
0.10
3.0
3.00
10 x 8
0.75
5.25
exceptional lustre and brilliant fire, makes
Topaz can be found in a variety of
stone’s colouring. Regarded as a deeply
pale yellow to dark orange.
0.11
3.1
3.50
10 x 8.5
1.00
5.5
it the most highly prized of all gems.
colours including blue, yellow, green,
religious stone it is thought to balance
0.12
3.2
4.00
11 x 9
1.25
6.0
orange, pinkish-red and brown.
creativity and mental processes,
0.14
3.3
4.50
11 x 9.5
1.6
7.0
protecting against envy and fear.
0.15
3.4
5.00
12 x 10
2.25
8.0
0.16
3.5
0.17
3.6
Sapphire
Turquoise
Moonstone
Amethyst
0.18
3.7
0.20
3.8
One of the first gemstones ever used for
This gem is a variety of the mineral
This translucent stone is the best known
Is the best known form of quartz, colour
0.22
3.9
Corundum, which is the hardest
jewellery, this mineral was highly valued
variety of feldspar with an iridescent
ranging from deep to light purple.
0.25
4.0
mineral after diamond. The blue colour
Ancient belief held that anyone wearing
by the Egyptians as early as 6000 B.C.
sheen called “adularescence”. The
Marquise Stones
Emerald Cut Stones
0.30
4.2
and the depth of this colour is caused
an amethyst could not become
In Persian, Turquoise is known as
moonstone is still a sacred stone in India
0.33
4.4
carat to mm
carat to mm
Ferozah, meaning victorious and is the
by the presence and the amount of
where tradition holds the stone as a
intoxicated.
0.35
4.5
carat
mm
carat
mm
national gemstone of Iran to this day.
iron and titanium oxides in the mineral.
symbol of the Third Eye.
weight
size
0.38
4.6
weight
size
0.40
4.8
0.07
3.5 x 1.5
0.20
4 x 3
0.50
5.0
0.10
4 x 2
0.25
5 x 3
0.60
5.4
0.20
5 x 2
0.50
6 x 4
0.75
6.5 x 4.5
0.63
5.5
0.20 - 0.25
5 x 3
Emerald
Citrine
Pearl
Pink Sapphire
1.00
7 x 5
0.65
5.6
0.25
5.5 x 2.5
1.50
8 x 6
0.75
6.0
0.30
6 x 3
The earliest known gem market in
The golden lemon colour of this member
The cultured pearl has been produced
Pink sapphires occur in Sri Lanka,
2.00
8.5 x 6.5
0.95
6.4
0.35
7 x 3
Babylon was trading emeralds as early
of the quartz family has long been a
in China for several centuries but the
Burma, and East Africa. The colour
2.50
9 x 7
1.00
6.6
0.38
7 x 3.5
symbol of light heartedness and joy.
as 4000 BC. This gem is a variety of
modern industry was founded in Japan
varies from a very pale & delicate pink
3.00
10 x 8
1.17
6.8
0.40
7 x 4
4.00
11 x 9
the mineral Beryl and occurs within
in the late 19th century.
to a near-red. It is believed that if the
1.25
7.0
0.50
8 x 4
5.00
12 x 10
dark shales and limestones in
stone is worn directly on the skin it will
1.33
7.2
0.65
8.5 x 4.5
5.00
12 x 10
Colombia’s Muzor and Chivor regions.
ward off ill-health & misfortune.
1.50 - 1.75
7.5
0.70
9 x 4
1.75
7.8
0.75
9 x 4.5
2.00
8.0
0.80
9 x 5
2.15
8.4
0.85
9.5 x 4.5
Ruby
Pink Tourmaline
Garnet
Tanzanite
2.25
8.6
1.00
10.0 x 4.75
2.50 - 3.00
9.0
1.00 - 1.25
10.0 x 5
The rich red of ruby is produced by the
The name Tourmaline is said to have
Its blood red colour has been likened to
An indigo blue variety of the mineral zoisite, it
3.00
9.4
1.50
11.0 x 5
was found for the first time in 1967 and named
presence of chromium in the mineral
originated from the Sinhalese term, ‘turmali’
the flesh of a ripe pomegranate and the
Pear Shaped Stones
3.15
9.6
1.50 - 1.75
11 x 5.5
by Tiffany & Co in New York after its originating
Corundum. The best ruby colour is
meaning ‘mixed’. Its unusually bright shade
name garnet is derived from the Latin
3.35
9.8
2.00
12 x 6
carat to mm
country. Supremely rare, tanzanite comes from
described as “pigeon’s blood” and is
of pink is said to bring compassion, trust
word granatum.
3.50
10.0
2.50
13 x 5.5
carat
mm
found in the Mogok area of Burma.
and self-love. Referred to as the ‘muses’
only one place in the world, the Merelani Hills
weight
size
3.75
10.2
2.50 - 2.75
13 x 6
stone, many believe that its imaginative
of Tanzania. Many believe it helps to foster
4.00
10.4
2.75 - 3.00
14 x 6.5
0.20
4 x 2
achievement and assists in exploring aspects
colours contain inspirational powers.
4.25
10.6
3.00
14 x 7
0.30
5 x 3
of the self.
0.50
6 x 4
4.50
10.8
3.50 - 4.00
15 x 7
4.75
11.0
4.50
16 x 8
0.75
7 x 5
Opal
Peridot
Onyx
Rhodolite
5.00
11.2
7.00
18 x 9
1.00
8 x 5
6.00 - 7.00
12.0
10.00
20 x 10
1.50
9 x 6
Ancient Romans believed opal to be a
The attraction of this stone lies in its rich
Primarily sourced in the U.S, Germany
Rhodolite, sometimes known as
2.00
10 x 7
symbol of hope because it contained the
“oily” green colour, which ranges from
and Mexico, Onyx occurs naturally in
Raspberry Rhodolite Garnet is a
2.50
12 x 7
colours of the rainbow. Arabs thought
pale golden green to brownish green.
black but can also be found in brown,
combination of almandine and pyrope.
3.00
12 x 8
the fiery colour was created while falling
It was first found on St. John’s Island
grey and white. The stone is believed to
The name is derived from the Greek
3.50
13 x 8
from the sky in flashes of lightning.
in the Red Sea as early as 1300 BC but
help change bad habits, and is also
words rhodon and lithos, meaning
4.00
14 x 8
now mined in Arizona, Burma and Norway.
thought to be useful in deflecting and
rose-stone. It is believed to balance
5.00
15 x 9
absorbing the negativity of others.
emotion and foster greater awareness.
Please Note: The weight may vary depending on the depth of the diamond.
why not order online at
or by phone call
or call into one of our trade counters
0845 100 1122
in London’s Hatton Garden or
local rate
Birmingham’s Jewellery Quarter
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