Size Charts

Size/Weight Comparison Charts

How to use these charts: Gemstones will vary slightly because of the different densities of the the stone, For example you can see from the first chart that a 6mm round brilliant diamond might weigh 0.90 ct while a 6mm Ruby in an equivalent 6mm size would weigh approximately 1.05 cts. These numbers are estimates only and can vary based on a stones depth, but should still give you a general idea on how density can effect a stones weight.

ROUND BRILLIANT CUT STONES

GEMSTONE

2mm

3mm

4mm

5mm

6mm

7mm

8mm

Alexandrite

.04

.12

.35

.63

1.30

2.15

2.90

Amethyst

.04

.10

.20

.40

.70

1.30

1.80

Aquamarine

.04

.10

.25

.45

.75

1.60

2.40

Citrine

.04

.10

.20

.40

.70

1.30

1.80

Diamond

.04

.10

.23

.47

.90

1.35

1.90

Emerald

.04

.12

.27

.48

.80

1.70

2.50

Garnet

.05

.13

.30

.60

1.00

1.60

2.50

Opal

.02

.09

.16

.34

.57

.83

1.30

Peridot

.05

.12

.26

.50

.85

1.25

2.00

Ruby

.05

.15

.34

.65

1.05

1.60

2.25

Sapphire

.05

.15

.34

.65

1.05

1.60

2.25

Topaz

.04

.11

.30

.56

1.00

1.55

2.50

Tourmaline

.04

.12

.24

.45

.75

1.55

2.00

Zircon

.06

.17

.36

.69

1.25

1.75

2.60

OVAL CUT STONES

GEMSTONE

5x3

6x4

7x5

8x6

9x7

10x8

11x9

12x10

14x10

16x12

18x13

Alexandrite

.30

.61

.80

1.45

2.00

3.60

4.25

6.00

8.90

12.50

18.00

Amethyst

.23

.45

.85

1.25

1.75

2.40

3.20

4.50

6.50

11.00

14.00

Aquamarine

.20

.40

.75

1.10

1.75

2.25

3.00

4.50

6.75

10.15

10.57

Citrine

.23

.45

.85

1.25

1.75

2.40

3.25

4.20

5.20

9.00

10.75

Diamond

.25

.50

.75

1.40

2.00

3.00

4.00

5.00

8.00

11.50

16.00

Emerald

.28

.52

.85

1.00

1.60

2.25

3.75

5.00

7.50

12.00

14.50

Garnet

.25

.55

1.00

1.40

2.10

2.80

3.75

5.00

7.00

10.00

13.25

Opal

.16

.28

.47

.75

1.10

1.65

2.15

3.00

4.00

5.25

5.75

Peridot

.28

.50

.95

1.35

2.00

2.50

3.50

4.00

6.00

9.50

13.00

Ruby

.35

.60

1.00

1.55

2.20

3.15

3.80

6.00

7.25

12.00

13.00

Sapphire

.35

.60

1.00

1.55

2.20

3.15

3.80

6.00

7.25

12.00

13.00

Topaz

.27

.57

1.10

1.60

2.50

3.50

4.50

6.00

8.80

12.00

17.00

Tourmaline

.25

.50

.90

1.18

2.30

2.90

3.50

5.25

6.80

8.50

12.00

Zircon

.40

.75

1.45

2.00

2.85

4.00

5.60

7.50

8.20

13.50

14.50

 

EMERALD CUT STONES

GEMSTONE

5x3

6x4

7x5

8x6

9x7

10x8

11x9

12x10

14x10

16x12

18x13

Alexandrite

.40

.70

1.30

2.60

3.60

4.20

6.00

8.50

9.90

14.50

22.00

Amethyst

.35

.55

1.00

1.60

2.25

2.90

4.20

5.60

7.25

13.00

17.00

Aquamarine

.25

.50

.80

1.40

2.00

3.00

4.30

4.75

7.75

13.50

17.00

Citrine

.35

.55

1.00

1.60

2.25

2.90

4.20

5.60

7.25

13.00

17.00

Diamond

.25

.50

1.00

1.50

3.00

4.00

5.00

7.8

8.80

13.00

20.00

Emerald

.30

.60

.90

1.80

2.31

3.15

4.50

5.25

5.80

14.00

17.50

Garnet

.40

.80

1.20

1.70

2.50

3.50

4.30

6.35

9.00

17.50

21.00

Peridot

.35

.60

1.00

1.70

2.25

3.80

5.25

6.25

8.80

17.00

20.00

Ruby

.55

.75

1.15

1.75

2.30

2.75

4.00

6.25

9.00

12.50

18.70

Sapphire

.55

.75

1.15

1.75

2.30

2.75

4.00

6.25

9.00

12.50

18.70

Topaz

.40

.65

1.25

2.40

3.40

4.00

5.75

8.00

9.50

14.00

21.00

Tourmaline

.30

.60

1.60

2.15

2.80

3.60

4.30

5.20

8.50

13.00

16.50

Zircon

.60

.80

1.70

2.35

3.90

4.50

6.20

7.05

8.95

14.30

19.90

PEAR CUT STONES

GEMSTONE

5x3

6x4

7x5

8x5

9x6

10x7

13x8

14x10

Alexandrite

.30

.50

.85

1.10

2.10

3.60

6.60

8.80

Amethyst

.20

.35

.65

.85

1.25

1.70

4.00

5.00

Aquamarine

.20

.35

.65

.90

1.30

1.85

4.20

5.60

Citrine

.20

.35

.65

.85

1.30

1.70

4.00

5.00

Diamond

.25

.50

.75

1.00

1.50

2.00

3.50

5.00

Emerald

.25

.45

.70

1.05

1.70

2.60

4.15

6.10

Garnet

.25

.40

1.00

1.15

1.30

1.80

3.50

5.80

Opal

.13

.22

.35

.50

.70

1.03

1.40

2.45

Peridot

.25

.45

.70

.80

1.10

1.40

3.40

4.75

Ruby

.30

.50

.75

1.00

1.85

2.50

4.75

7.90

Sapphire

.30

.50

.75

1.00

1.85

2.50

4.75

7.90

Topaz

.25

.50

1.00

1.10

2.00

3.50

6.50

8.50

Tourmaline

.35

.45

.60

.90

1.10

1.40

2.80

6.75

Zircon

.30

.70

1.00

1.30

2.60

4.00

5.25

7.50

 

MARQUISE CUT STONES

 

GEMSTONE

4x2

6x3

8x4

10x5

12x6

14x7

Alexandrite

.07

.30

.70

1.25

2.10

3.50

Amethyst

.10

.20

.48

.90

1.59

2.45

Aquamarine

.08

.20

.50

.80

1.50

2.75

Citrine

.10

.20

.50

.90

1.59

2.45

Diamond

.12

.25

.50

1.00

2.00

3.00

Emerald

.09

.30

.60

1.10

1.80

2.80

Garnet

.09

.25

.60

1.20

2.00

2.85

Opal

.09

.17

.37

.59

1.00

1.25

Peridot

.10

.25

.50

1.00

2.00

2.55

Ruby

.13

.35

.75

1.15

2.20

3.00

Sapphire

.13

.35

.75

1.15

2.20

3.00

Topaz

.07

.30

.70

1.20

2.00

3.40

Tourmaline

.10

.30

.60

.85

1.55

2.20

Zircon

.13

.33

.75

1.25

1.95

3.00

Physical Properties of Gemstones

Name Hardness Chemical Composition Density
Alexandrite 8.5 BeAl2O4 3.73
Amethyst 7 SiO2 2.66
Ametrine 7 SiO2 2.66
Beryl 7.5 Be3Al2(SiO3)6 2.67-2.745
Chrome Tourmaline 7-7.5 (NaCa)(LI,MgFe,Al)9B3Si6(O,OH)31 3.06 (.05, +.15)
Chrysoberyl 8.5 BeAl2O4 3.73
Chrysoberyl Cats Eye 8.5 BeAl2O4 3.73
Diamond 10 C 3.52
Emerald 7.5-8 Be3Al2(SiO3)6 2.72 (-.05, +.12)
Kyanite 4.5 - 7.0 AL2SIO5 3.56 - 3.68
Malaia Garnet 7 - 7.5 [Mg3 + Mn3]AL2(SIO4) 3.65 - 4.20
Mali Garnet 7.25 Ca3Al2(SiO4)3 3.65
Opal 5.5 - 6.0 SIO2nH2O 2.65 - 3.00
Peridot 6.5 (Mg,Fe)2(SiO)4 3.34
Quartz 7 SiO2 2.65
Ruby 9 AL2O3 4
Sapphire 9 AL22O3 4
Spessartite Garnet 7.25 Mn3Al2(SiO4)3 4.14-4.20
Spinel 8 MgAl2O4 3.60 (-.03, +.30)
Star Sapphire 9 AL2O3 4
Tanzanite 6-7 Ca2(Al,OH)Al2(SIO4) 3.30 (+.10, -.10)
Topaz 8 AL(F,OH)2SIO4 3.52 - 3.56
Tourmaline 7-7.5 (NaCa)(LI,MgFe,Al)9B3Si6(O,OH)31 3.06 (.05, +.15)
Tsavorite 7 Ca3Al2(SiO4)3 3.61(-.27, +.12)
Turquoise 5.5-6 CuAl6(PO4)4(OH)85H2O 2.60- 2.90
Zircon 7.5 ZrSiO4 4.00-4.73

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